2020-54 - OENGINEERING DESIGN STANDARDS
SECTION 4 – ROADWAY DESIGN STANDARDS
Ordinance No. 2020-54, Page 3
ENGINEERING DESIGN STANDARDS
4-2
4.01. General
The arrangement, character, extent, width and location of all streets shall be in general
conformity with the Town’s Thoroughfare Plan and Comprehensive Plan, and should be
considered in their relation to existing and planned streets, topographical and
environmental considerations, scenic views and the land uses proposed to be served by
such streets.
The Town of Prosper shall approve the location of all public roadways, all driveway
connections to public roadways, and all mutual access driveways between properties.
Where a proposed public roadway or mutual access driveway will cross a property line,
both property owners shall consent to the alignment; if the property owners fail to agree
on an alignment, the alignment shall be determined by the Director of Engineering
Services.
All thoroughfare and other roadway designs shall meet the guidelines in AASHTO’s
current A Policy on Geometric Design of Highways and Streets, and all street signs and
pavements markings shall meet the guidelines in the current edition of the Manual of
Uniform Traffic Control Devices.
4.02. Street Design
A.Thoroughfare Definitions - The Town of Prosper recognizes four basic classifications
of public roadways that include freeways, thoroughfares, collectors, and local streets
as identified in the transportation element of the Comprehensive Plan. Each class
provides a certain degree of continuity, capacity, and accessibility to adjacent land
uses. While differentiated by function, there is also a variance in geometric design.
Table 4.1 summarizes the general design criteria of roadways within Prosper. The
typical cross-sections are depicted in Figure 4.1.
B.Roadway Geometrics - Geometrics of city streets may be defined as the geometry of
the pavement and curb areas that govern the movement of traffic within the confines
of the rights-of- way (ROW). Included in the geometrics are pavement width, degree
of curvature, width of traffic lanes, median nose radii, curb radii at street intersections,
cross fall, crown height, pavement thickness and geometric shapes of islands
separating traffic movements and other features.
1.Design Speed - The design speed is a primary factor in the horizontal and vertical
alignment of roadways. Design features such as curvature, super-elevation,
turning movement radii and sight distance affects roadway lane width, pavement
width, pavement cross-fall, pavement crown and clearances. The design speeds
depicted shall be used where existing ground slopes are less than six percent
(6%). Refer to Table 4.1.
2.Grades - Roadway grades shall be a minimum of six-tenths percent (0.6%) in order
to insure proper flow of surface drainage toward inlets and a maximum of six
percent (6%). Steeper grades may be permitted on local residential streets and
where required by topographical features, as approved by the Director of
Engineering Services or their designee.
Ordinance No. 2020-54, Page 4
ENGINEERING DESIGN STANDARDS
4-3
3. Roadway Centerline - Roadways shall be placed in the center of the ROW, but
may be shifted slightly to avoid groupings of trees. The centerline of curves shall
be tangent to the centerline of street at each end of curve.
4. Cross Fall/Crown Height – 6LD and 4LD thoroughfares shall have a minimum
cross fall of one- quarter inch per foot and a maximum cross fall of three-eighths
inch per foot. 3L and 2LC thoroughfares shall have six-inch (6”) parabolic crowns,
and 2LN and 2LRN thoroughfares a five-inch (5”) parabolic crown.
5. Pavement Thickness -. Refer to Table 4.1 for pavement thickness. The Town
Paving and Subgrade Manual provides detailed design requirements for all street
types.
TABLE 4.1: Town of Prosper Thoroughfare Definitions
Criteria
Thoroughfare Class
Ultimate
Major 6LD
Interim(2)
4/6LD
Minor
4LD
Comm.
Couplet 3L
Collector
2LC
Local
2LN/2LRN
Right-of-Way (ROW) 120’(5) 120’(5) 90’(6) 65’ 60’ 50’/50’min.
Pavement Width (face-face) 2 @ 36’ 2 @ 24’ 2 @ 24’ 53’(3) 36’(8) 30’ / 26’
Traffic Lanes 6 4 4 2 2 2
Shoulder Width -- -- -- -- -- -- / 2’
Left Turn-lane Width 2 @ 10’ 1 @ 12’ 1 @ 10’ -- -- --
Right Turn-lane Width 11’ 11’ 11’ -- -- --
Median Width 24’ 48’ 18’ -- -- --
Parkway Width 12’ 12’ 12’ 6’ 12’ 10’/12’
Ditch Width -- -- -- -- -- -- / 10’min.
Minimum Pavement 9” 9” 9” 7” 7” 6”
Design Speed, V (MPH) 50 50 45 35 30 25
Minimum Grade 0.6% 0.6% 0.6% 0.6% 0.6% 0.6%
Maximum Grade 6% 6% 6% 6% 6% 6%
Min. Horizontal Radii(1) 1,400’ 1,400’ 1,100’ 450’ 450’ 300’(4)
Min. Tangent Between 100’ 100’ 100’ 100’ 100’ --
Min. Length of Crest Curve See Table 4.3
Min. Length of Sag See Table 4.4
Stopping Sight Distance 425’ 425’ 360’ 200’ 200’ 155’
Parking None None None Permitted Permitted Permitted
Volume Range (VPD) 36-45,000 20-28,000 20-28,000 12-18,000 6-12,000 --
(1) Absolute minimum based on 2% cross slope.
(2) Four lane thoroughfare built in ROW of a 6LD thoroughfare so it can be widened in the future.
(3) Pavement of Commercial Couplet 3L includes 37’ of travel way with 8’ of parking on either side.
(4) May be reduced to two hundred feet (200’) radius at mid-block locations provided that it is shown
that the general public safety is not compromised. A curve, with a radius less than two hundred
fifty feet (250’), must be a minimum of three hundred feet (300’) from a street or alley intersection.
(5) 140’ ROW at intersections with a 4 or 6 lane thoroughfare.
(6) 110’ ROW at intersections with a 4 or 6 lane thoroughfare.
(7) Thickness shall be based on the geotechnical soils report. The Paving and Subgrade Manual
provides detailed design requirements for all street types.
(8) Roadways adjacent to a neighborhood park or school shall have a minimum pavement width of 36’.
Ordinance No. 2020-54, Page 5
ENGINEERING DESIGN STANDARDS
4-4
Ultimate Major Thoroughfare ‘6LD’ (Intersection)
Ultimate Major Thoroughfare ‘6LD’ (at DNT Frontage Roads)
Ultimate Major Thoroughfare ‘6LD’ (Midblock)
Interim Major Thoroughfare ‘4/6LD’ (Intersection)
22' PKWY
2'
107'
36'24' MEDIAN 47'
140'
11'
PKWY
2'
11'12'12'12'
10' LEFT
TURN
10' LEFT
TURN12'12'12'R.O.W.R.O.W.6' SIDEWALK 6' SIDEWALK
140'
22' PKWY 24'48' MEDIAN 35'
11'
PKWY
107'
2'12'12'12' LEFT
TURN 12'12'11'2'R.O.W.R.O.W.6' SIDEWALK 6' SIDEWALK
12' PKWY 36'24' MEDIAN 36'12' PKWY
140'
12'12'12'12'12'12'2'2'
6' SIDEWALK6' SIDEWALK
Ordinance No. 2020-54, Page 6
ENGINEERING DESIGN STANDARDS
4-5
Interim Major Thoroughfare ‘4/6LD’ (Midblock)
Minor Thoroughfare ‘4LD’ (Intersection)
Minor Thoroughfare ‘4LD’ (Midblock)
Commercial Couplet ‘3L’
120'
96'
24'48' MEDIAN 24'12' PKWY12' PKWY
12'12'15'15'12'12'
2'2'
CLEAR
ZONE
CLEAR
ZONER.O.W.R.O.W.6' SIDEWALK6' SIDEWALK
R.O.W.R.O.W.6' SIDEWALK 6' SIDEWALK
110'
77'22'
PKWY 24'18' MEDIAN 35'
11'
PKWY
12'12'
10' LEFT
TURN 12'12'11'2'2'
90'
66'
12'
PKWY 24'18' MEDIAN 24'
12'
PKWY
12'12'12'12'2'2'R.O.W.R.O.W.6' SIDEWALK6' SIDEWALK
Center Lane
Thru
Side Walk
Parallel
Parking
Parallel
Parking Side Walk
ThruR.O.W.R.O.W.37'
6'8'12'13'12'8'6'
65'
Ordinance No. 2020-54, Page 7
ENGINEERING DESIGN STANDARDS
4-6
Collector Street ‘2LC’
(Commercial and Residential)
Neighborhood Street ‘2LN’
Rural
Neighborhood Street ‘2LRN’
Divided Residential Subdivision Entrance
FIGURE 4.1: Typical Roadway Cross-Sections
60'
12'
Parkway 36'
Thru Thru R.O.W.R.O.W.5' SIDEWALK 5' SIDEWALK
12'
Parkway
18'18'2'2'
50'
10'
Parkway 30'
10'
Parkway
15'15'2'2'
Thru Thru R.O.W.R.O.W.5' SIDEWALK 5' SIDEWALK
50' Minimum*
10'**26'10'**
10' Min*13'13'10' Min
Thru Thru
DITCH DITCH2' SHLDR2' SHLDR*Varies depending on drainage area calculations
**Clear ZoneR.O.W.R.O.W.Thru
ThruR.O.W.R.O.W.5' SIDEWALK5' SIDEWALK
85'
61'
12'
PKWY 24'13' MEDIAN 24'
12'
PKWY
2'2'
Ordinance No. 2020-54, Page 8
ENGINEERING DESIGN STANDARDS
4-7
C. Minimum Horizontal Design Radius:
1. The minimum centerline radius is a function of design speed, super-elevation and
vehicle side friction. Side friction is the force that keeps a vehicle from sliding off
the roadway. The minimum acceptable horizontal centerline radius is calculated
using the following equation:
ܴ ሺ݂ݐ.ሻ ൌ ܸ ଶ
15ሺ݁ ݂ሻ
Where: R = centerline radius (ft); V = vehicle design speed (MPH); e = rate of
roadway super-elevation (ft/ft); f = side friction factor (Table 4.2)
2. The minimum acceptable horizontal radius is shown in Table 4.2. The maximum
length of a horizontal curve on 3L, 2LC, 2LN and 2LRN thoroughfares shall not
exceed 1.6 times the centerline radius for a radius of two hundred feet (200’) or
greater.
TABLE 4.2: Minimum Horizontal Centerline Radius
Design Speed V
(MPH) f e (ft/ft) R (ft) (Rounded for
Design)
25 0.165 -0.02 300(1)
30 0.160 -0.02 450
40 0.150 -0.02 600
45 0.145 -0.02 1,100
50 0.140 -0.02 1,400
1) May be reduced to two hundred feet (200’) radius at mid-block locations provided that it is
shown that the general public safety is not compromised. A curve, with a radius less than two
hundred fifty feet (250’), must be a minimum of three hundred feet (300’) from a street or alley
intersection.
Ordinance No. 2020-54, Page 9
ENGINEERING DESIGN STANDARDS
4-8
D. Minimum Vertical Alignment:
1. Vertical curves are utilized in roadway design to affect gradual change between
tangent grades and will result in a design which is safe, comfortable in operation,
pleasing in appearance and adequate for drainage. Vertical curve alignment shall
also provide Stopping Sight Distance (SSD) in all cases. SSD is a function of
design speed, perception-reaction time, grade, and vehicle deceleration. The
perception-reaction time is assumed to be 2.5 seconds as stated by the American
Association of State Highway and Transportation Officials (AASHTO). The vehicle
deceleration is assumed to be 11.2 feet per second per second (fps2) based upon
conservative pavement conditions and the ability of a vehicle to deceleration rate
on a level grade. The equation for SSD appears below:
ܵܵܦ ൌ 1.47ܸܲ 1.075
ܸ ଶ
ܽ
Where: SSD = Stopping Sight Distance (ft); P = Perception Reaction Time (2.5
sec.); V = vehicle design speed (MPH); a = vehicle deceleration rate (11.2 fps2)
2. The minimum acceptable length of Crest and Sag curves are shown in Tables 4.3
and 4.4. Tables 4.3 and 4.4 also show values of K. K is defined as the rate of
vertical curvature and is equivalent to the horizontal distance in feet required to
make a one percent (1%) change in grade. The values of A are equivalent to the
algebraic difference in grade between the two grades that are being joined together
by the vertical curve.
Ordinance No. 2020-54, Page 10
ENGINEERING DESIGN STANDARDS
4-9
TABLE 4.3: Minimum Acceptable Crest Curve Given Speed and Difference in Grade of
Road
Design
Speed,
V
(MPH)
SSD
(ft) K
Length of Vertical Curve, ft (L=KA)
A=1
(1) A=2 A=3 A=4 A=5 A=6 A=7 A=8 A=9 A=1
0
25 155 12 -- 100 100 100 100 100 100 100 110 120
30 200 19 -- 100 100 100 100 120 140 150 170 190
35 250 29 -- 100 100 120 150 180 200 230 260 290
40 305 44 100 100 130 180 220 270 310 350 400 440
45 360 61 100 120 180 250 310 370 430 490 550 610
50 425 84 100 170 250 340 420 510 590 670 760 840
(1)Speeds less than forty miles per hour (40 MPH), no vertical curve is necessary. Speeds
greater than forty miles per hour (40 MPH), use length of one hundred feet (100’).
TABLE 4.4: Minimum Acceptable Sag Curve Given Speed and Difference in Grade of
Road
Design
Speed,
V
(MPH)
SSD
(ft) K
Length of Vertical Curve, ft (L=KA)
A=1
(1) A=2 A=3 A=4 A=5 A=6 A=7 A=8 A=9 A=10
25 155 26 -- 100 100 110 130 160 180 210 240 260
30 200 37 -- 100 110 150 190 220 260 300 330 370
35 250 49 -- 100 150 200 250 300 340 390 440 490
40 305 64 100 130 190 260 320 390 450 510 580 640
45 360 79 100 160 240 320 400 480 550 630 710 790
50 425 96 100 190 290 390 480 580 670 770 870 960
(1)Speeds less than forty miles per hour (40 MPH), no vertical curve is necessary. Speeds
greater than forty miles per hour (40 MPH), use length of one hundred feet (100’).
E. Standard Intersection Layout:
1. Street intersections shall intersect at ninety-degree (90°) angles. Intersection
approaches for 4 or 6 lane thoroughfares shall remain perpendicular for a minimum
distance equal to the corresponding design speed Stopping Sight Distance (SSD)
identified in Table 4.3. For residential collector and/or local street intersections, a
five-degree (5°) tolerance is allowable.
2. The curb radii shall be twenty feet (20’) where 2 lane thoroughfares intersect with
other 2 lane thoroughfares. All other intersecting streets, curb radii shall be thirty
feet (30’).
Advisory Note: Values provided in Table 4.3 and 4.4. are minimum standards for stopping sight distance
requirements. However, maximum design lengths should be considered to allow prosper drainage.
Ordinance No. 2020-54, Page 11
ENGINEERING DESIGN STANDARDS
4-10
3. Intersection of 4 or 6 lane thoroughfares with other 4 or 6 lane thoroughfares shall
maintain a maximum slope of two percent (2%) a minimum distance of two
hundred feet (200’) upstream and downstream of the intersection.
4. Roadway connections to a 4 or 6 lane thoroughfare shall maintain a maximum
slope of two percent (2%) a minimum distance of one hundred feet (100’) upstream
and downstream of the intersection.
5. A separate grading plan shall be provided for intersections of 4 or 6 lane
thoroughfares with other 4 or 6 lane thoroughfares.
6. At four-way intersections of parabolic streets, the reduction of the crown height
shall occur on the thoroughfare with the through gutter.
a) For 3L and 2LC thoroughfares, the crown height reduction from six inches (6”) to
three inches (3”) shall occur through the intersection and transition from the curb
return to a point fifty feet (50’) past the curb return.
b) For 2LN and 2LRN thoroughfares, the crown height reduction from five inches (5”)
to three inches (3”) shall occur through the intersection and transition from curb
return to a point thirty feet (30’) past the curb return.
7. Alley curb radii shall be fifteen feet (15’).
8. A minimum of nine and a half feet (9.5’) of parkway shall be maintained from the
back of the curb along the curb’s radius.
9. ROW width for 6LD or 4/6LD thoroughfare that intersects a 4 or 6 lane thoroughfare
shall be one hundred forty feet (140’) for a distance of two hundred feet (200’) from
the intersection and then taper at a 15:1 ratio to the standard ROW width. This
allows for the future construction of additional traffic lanes at the intersection. See
Figure 4.2.
FIGURE 4.2: Major Intersection Detail (6LD or 4/6LD Thoroughfare)
10. ROW width for a 4LD thoroughfare that intersects a 4 or 6 lane thoroughfare shall
be one hundred ten feet (110’) for a distance of one hundred fifty feet (150’) from
Ordinance No. 2020-54, Page 12
ENGINEERING DESIGN STANDARDS
4-11
the intersection and then taper at a 15:1 ratio to the standard ROW width to allow
build-out of the intersection. See Figure 4.3.
FIGURE 4.3: Minor Intersection Detail (4LD Thoroughfare)
F. Roundabouts
1. Roundabouts may be considered for the intersection of 4LD, 3L, and 2LC, roads
with 4LD, 3L, 2LC, and 2LN. Roundabouts may also be considered for
intersections along interim major thoroughfares (4LD/6LD) that have not yet been
widened to six lanes. Roundabouts shall not be installed at the intersection of two
6LD thoroughfares, 6LD-4LD thoroughfares, or two 4LD thoroughfares without a
detailed traffic simulation and cost-benefit analysis approved by the Director of
Engineering Services. Roundabouts shall not be installed along a 6LD
thoroughfare.
2. Roundabouts on private property that connect to a private street or to a fire lane
shall be designed to the standards in these design requirements.
3. Roundabouts shall be designed to accommodate a Town fire truck making all
possible entry and exit movements. A fire truck shall be able to make the “through”
movement without traveling on a truck apron. Roundabouts located along a 6LD,
4LD, or 2LC thoroughfare shall also accommodate a WB-67 design vehicle.
4. Roundabouts shall include the typical features of a modern roundabout shown in
Figure 4.4 and described in these design requirements.
5. The curb surrounding the central island shall be six inch (6”) vertical curb if a truck
apron is provided and six inch (6”) mountable curb if no truck apron is provided.
The curb surrounding a truck apron shall be three inch (3”) mountable curb. The
curb surrounding all faces of each splinter island shall be four inch (4”) mountable
curb.
6. The inscribed circle radius shall be minimum of fifty-five feet (55’) and a maximum
of eighty feet (80’) for a single lane roundabout, and a minimum of seventy-five
feet (75’) and a maximum of a hundred feet (100’) for a two-lane roundabout.
Ordinance No. 2020-54, Page 13
ENGINEERING DESIGN STANDARDS
4-12
FIGURE 4.4: Typical Roundabout
7. The circulatory roadway shall have a minimum width of sixteen feet (16’), face-to-
face. The circulatory roadway shall be at least as wide as the maximum entry width
at the roundabout. If the circulatory roadway is less than twenty-nine feet (29’)
wide, face-to-face, a truck apron shall be provided. The combined width of the
circulatory roadway and the truck apron shall be a minimum of twenty-nine feet
(29’). Truck aprons shall provide a solid surface of concrete pavers that are a
contrasting color compared to the pavement of the circulatory roadway and shall
not give the appearance of being a sidewalk.
8. Single lane entries and exits shall be a minimum of sixteen feet (16’) wide, face to
face. Two-lane entries and exits shall be a minimum of twenty-four feet (24’) wide,
face to face.
9. Splitter islands shall provide a solid surface of concrete pavers unless the entry
and exit on the same leg of the roundabout are both at least twenty-four feet (24’)
wide, face to face. The pavers shall be a contrasting color compared to the street
pavement and no signs shall be installed in the splitter island. If pavers are not
required, the splitter island can contain Town approved landscaping provided it
does not interfere with the necessary sight distance.
10. Crosswalks shall pass through or in advance of each splitter island.
Ordinance No. 2020-54, Page 14
ENGINEERING DESIGN STANDARDS
4-13
11. All streets, fire lanes, and approved driveways shall intersect radially with a
roundabout. Residential driveways and alleys shall not intersect with a roundabout
(including the splitter island components).
12. The design of any roundabout located along a 4LD or 2LC thoroughfare shall
include calculations of the vehicle entry path deflection (fastest path) in each
direction. Each critical radius along the fastest path must be shown to reduce
speeds to the desirable levels shown in the latest edition of FHWA’s Roundabouts:
An Informational Guide.
13. Landscaping and/or monuments within the central island are encouraged, but shall
be limited so that the minimum sight distance described in the latest edition of
FHWA’s Roundabouts: An Informational Guide are provided at the roundabout.
For vehicles approaching the roundabout, this includes the approach stopping
sight distance to the crosswalk or the yield line, the stopping sight distance to the
crosswalk on the next exit, and the intersection sight distance to circulating
vehicles and vehicles entering at the immediate upstream entry. For circulating
vehicles, this includes the stopping sight distance on the circulatory roadway.
14. Parking is prohibited within a roundabout.
15. On any approach to a roundabout, driveways, alley connections, and on-street
parking shall not be permitted between the crosswalk and the yield line nor along
any portion of street that contains a splitter island.
16. No building (e.g., a home, amenity center, school, business, sports facility, etc.)
shall front onto a roundabout or have a private driveway or pedestrian entrance
facing the roundabout in a way that would encourage motorists to park, stop, or
stand in the roundabout. No building shall be located adjacent to a roundabout in
a way that would have the roundabout serve as its primary fire protection and/or
emergency response staging area.
17. The ROW for a roundabout shall extend a minimum of twelve feet (12’) beyond the
back of its outer curb. The ROW for any street entering the roundabout will flare
out as the street flares so that a minimum of twelve feet (12’) is provided beyond
the back of curb on each side of the street.
18. The roundabout entries and exists and the pavement contained within the
inscribed circle radius shall be constructed on a uniform plane of the same grade,
which shall not exceed two percent (2%) Roadway approaches to the roundabout
shall have a maximum slope of two percent (2%) for a distance of at least two
hundred feet (200’) for 4LD thoroughfares and at least one hundred feet (100’) for
2LC thoroughfares.
19. Roundabouts shall be illuminated by street lights as described in the latest edition
of FHWA’s Roundabouts: An Informational Guide.
20. The design of any roundabout located along a 4LD or 2LC thoroughfare shall
include calculations of the vehicle entry path deflection (fastest path) in each
direction. Each critical radius along the fastest path must be shown to reduce
speeds to the desirable levels shown in the latest edition of FHWA’s Roundabouts:
An Informational Guide.
Ordinance No. 2020-54, Page 15
ENGINEERING DESIGN STANDARDS
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G. Residential Frontage - Residential units, except for multifamily and townhome units,
shall not front or side a 6LD, 4/6LD, 4LD, 4LRD, 3L or 2LC thoroughfare (with limited
exceptions for 2LC as stated below) roadways unless parallel access roads are
provided. Minimum distances between adjacent curbs of the thoroughfare and the
access road shall be twenty feet (20’). Access road ROW shall be in addition to the
thoroughfare ROW and shall not connect to the adjacent thoroughfare.
1. In accordance with Town of Prosper Subdivision Ordnance, no residential roadway
(2LN) shall connect to thoroughfare roadways. Residential developments must
connect with a collector roadway (2LC) or a divided roadway (which shall consist
of two 24-foot lanes, a minimum of 4-foot median and 9.5 foot parkways) to a major
or minor thoroughfare.
2. This collector or divided roadway can terminate at the first intersection or transition
after sixty (60) feet measured from the thoroughfare right-of-way line. Longer 2LC
section may be required due to size of development as determined by the Director
of Engineering Services. Transitioning from collector (2LC) to residential (2LN)
section must be done in a minimum of 30 feet.
3. Residential units may front this entry 2LC for no more than half of the length of the
collector (2LC) section. Residential driveways shall be prohibited from connecting
to the 2LC roadway, any portion of a divided entry roadway, or the transition
section.
H. Street Lengths
1. Major and Minor (6LD, 4/6LD, 4LD) thoroughfares and commercial streets (3L,
commercial 2LC) have no street length restrictions. Residential streets (2LN,
2LRN, 2LC in a single-family, duplex, or townhome neighborhood) shall have
street length restrictions to discourage speeding and cut- through traffic. All street
length restrictions shall be measured from the ROW line of the intersecting street
on each end of the street being measured.
2. A residential street shall not directly connect to thoroughfares (6LD, 4/6LD, 4LD).
Residential roadways must connect to or transition from a collector or a subdivision
divided entry roadway which shall connect to the thoroughfare.
3. Residential streets (2LN and 2LRN) shall not have a straight tangent section over
eight hundred feet (800’) in length before requiring a “minor” traffic calming street
treatment. Residential streets with straight tangent sections shall not exceed two
thousand feet (2000’) before requiring a “major” traffic calming street treatment.
4. See Section 4.02.K for information on Minor and Major Traffic Calming Street
Treatments. Residential collectors (2LC) shall not have a straight tangent section
over one thousand two hundred feet (1200’) in length before a change in direction
or major traffic calming street treatment.
I. Block Length Requirements
Ordinance No. 2020-54, Page 16
ENGINEERING DESIGN STANDARDS
4-15
1. Residential blocks shall not exceed one thousand feet (1,000’) in length, measured
from street ROW line to street ROW line. In the case of non-rectangular blocks,
each side of the block with lots fronting onto it shall not exceed one thousand feet
(1,000’), measured between the vertices formed by the extension of ROW lines at
each corner of the block. Per Section 6.08.E. of the Town of Prosper Subdivision
Ordinance, a waiver to minimum block length may be approved by the Director of
Development Services.
2. Street Block Width – Blocks shall be wide enough to allow two tiers of lots and
shall have a block width of no less than 200 feet, except when only one tier of
lots is possible due to the size of the property or the need to back up to an
arterial.
J. Entrance Streets – A street serving a residential development that connects to a
major/minor thoroughfare shall meet the following requirements:
1. Unless approved as a cul-de-sac, all neighborhoods shall have a minimum of two
entrance streets.
2. A neighborhood with public residential streets shall have a minimum of two public
entrance streets. A public entrance street cannot be removed or converted to a
private entrance street unless the neighborhood retains at least two other public
entrance streets.
3. An entrance street shall be a minimum of thirty feet (36’) wide, face to face, or meet
the requirements of a divided residential street.
4. Each neighborhood shall have at least one entrance street designated as a primary
entrance street. Regardless of phased construction, neighborhoods that will
ultimately be larger than one hundred (100) acres in size, including any parks,
schools, or floodplain areas, shall have one primary entrance street on each
major/minor thoroughfare bounding the neighborhood. Individual neighborhoods
that will connect to other neighborhoods to eventually form a larger combined
neighborhood surrounded by major/minor thoroughfares shall each have a primary
entrance so that the combined neighborhood will eventually have at least one
primary entrance on each major/minor thoroughfare.
K. Curvilinear Streets – The majority of residential streets within a neighborhood are
encouraged to be curvilinear. If the criteria for curvilinear streets are met, the street
sections within the development will not require a Minor or Major Traffic Calming Street
Treatment. Curvilinear streets are as defined by the following requirements:
1. The centerline of a curvilinear street shall consist of one or more horizontal curves
or a combination of straight lines and horizontal curves. Each curve shall meet the
minimum radius requirements described in Subsection 4.02.C and shall have a
minimum arc length of one hundred twenty-five feet (125’).
2. A straight line drawn between the two ends of the centerline of a curvilinear street
shall cross over a curb in at least two locations along the length of the street. This
straight line shall be offset from the curb a minimum of thirty feet (30’) in at least
one location along the street so that a motorist on one end of the street cannot see
the other end.
Ordinance No. 2020-54, Page 17
ENGINEERING DESIGN STANDARDS
4-16
3. The closest residential street parallel to a major/minor thoroughfare is not required
to be curvilinear, but the design of the neighborhood shall become more curvilinear
as the distance from the major/minor thoroughfare increases. However, at no time
shall maximum tangent length for these streets be over 1200 feet.
4. The use of a street that is primarily straight with a short curve at one end of the
street shall be limited to streets whose straight end is perpendicular to the straight
edge of the neighborhood and is separated from that straight edge by no more
than one lot. However, a primarily straight street with a larger curve at one end of
the street that changes the direction of the street by ninety degrees (90°) can be
used in any location.
5. A short residential street that connects between two curvilinear streets is not
required to be curvilinear if it has no homes fronting onto it.
6. Curvilinear streets should follow the natural features of a site so that the leveling
and/or filling of the natural topography is minimized.
7. Curvilinear streets shall be designed so that the sight distance requirements in
Table 4.1 are maintained.
L. Other Street Designs and Requirements:
1. Any segment of a residential street that is adjacent to a school shall be constructed
with the 2LC Residential cross section. Chokers and pedestrian bulb-outs shall not
be used adjacent to a school without prior approval by the Director of Engineering
Services.
2. Any segment of a residential street that is adjacent to a park, or adjacent to an
HOA open space that has sufficient level space for one or more practice fields,
shall be constructed with the 2LC Residential cross section. If the 2LC Residential
cross section will extend for more than eight hundred feet (800’), midblock chokers
and pedestrian bulb-outs at intersections shall be used for traffic calming.
3. A choker is a midblock location where a residential street is narrowed to twenty-
two feet (22’) wide, face to face. A choker shall be twenty-five feet (25’) long, not
counting the taper on either end. Pedestrian bulb-outs are used at an intersection
to narrow the residential street to twenty-four feet (24’) wide, face to face, at the
location where pedestrians cross the street. Pedestrian bulb outs shall consist of
a fifteen foot (15’) tangent extending from the curb return. Chokers and pedestrian
bulb-outs shall contain landscaping or a sign to increase their visibility to motorists;
however, trees shall not be planted in them.
4. On-Street Parking - Where on-street parking is allowed, it shall operate as parallel
parking unless otherwise approved by the Director of Engineering Services. Where
head-in parking is approved by the Director of Engineering Services, the parking
spaces shall be angled in the direction of traffic flow on each side of the street,
assuming a vehicle pulls forward into a parking space. Where on-street angled
parking is used, the street shall provide a travel section that is no less than twenty-
four feet (24’) wide.
Advisory Note: Lots are encouraged to side a residential roadway adjacent to and serving an
elementary school in leu of fronting said street. Efforts should be made to side residential
lots where possible.
Ordinance No. 2020-54, Page 18
ENGINEERING DESIGN STANDARDS
4-17
5. Bike Lane Consideration – if a thoroughfare is designated as a bike route, the width
of the outside lane and the width of the ROW shall be increased by three feet (3’)
on 4 or 6 lane thoroughfares. For federal funding, five feet (5’) may be required.
M. Traffic Calming Street Treatments with Initial Design
To promote safe streets and discourage speeding through residential neighborhoods
when alignments cannot meet the requirements of section 4.02.K for curvilinear
streets, street design shall include the design elements as stated below. It shall be
the design consultant’s responsibility to analyze the suitability of all traffic calming
treatments and ensure adequate signage and/or pavement markings are installed,
appropriate sight distance is provided, and all other potential physical conditions have
been evaluated. Traffic calming treatments shall be done in a manner to not
significantly impact response times for emergency vehicles. Treatments shall also be
designed as to not impact other features of residential design which include, but not
limited to, street lights, fire hydrants, curb inlets, and barrier free ramps. Drainage
shall be considered in all treatments ensuring that street capacity and positive flow is
not compromised. All treatments shall follow the guidance and requirements as
identified by the FHWA “Traffic Calming ePrimer” resource when applicable (ITE
guidelines shall be used when FHWA guidelines do not cover all design requirements).
Traffic calming treatment shall only be allowed when physical constraints of the
property are such that the curvilinear requirments cannot be reasonably met. Any
traffic calming treatments shall require the pre-approval of both the Director of
Engineering Services and the Prosper Fire Marshal.
1. Minor Traffic Calming Treatments – required when straight tangent sections
exceed 800 ft in length. Treatments may include a combination of items listed
below and shall be spaced so no straight section without treatment shall exceed
600 ft in length (with the exception of raised intersections).
a. Enhanced pavement – includes stamped and stained (integral color) concrete
of a pattern and color that is cohesive with the neighborhood while color has
enough contrast to distinguish it. The enhanced pavement section shall be for
the full road width, but may exclude two (2) foot for the gutter and curb.
Enhanced pavement length shall be a minimum of 25 ft, and shall include a
section for every one hundred (100) feet over the maximum 800 ft straight
tangent section (if not combined with other minor treatments) equally spaced
throughout the straight section.
b. Raised Intersection – the full intersection, including crosswalks, of a 4-way
intersection shall be raised a height between 2.5 to 3 inches with 6-foot
approaches. Raised intersections shall only be allowed where the straight
section exceeding the maximum length does not warrant stop signs. Other
than 4-way intersections, raised intersections shall only be allowed on T-
intersections when opposite an open space lot so as not to hinder residential
lot access.
Ordinance No. 2020-54, Page 19
ENGINEERING DESIGN STANDARDS
4-18
c. Raised Crosswalk – raised crosswalks shall be designed with a raised height
between 2.5 to 3 inches with a 6-foot approach and shall only be used where
pedestrian traffic is intended to be higher than normal which shall include, but
not limited to, routes to schools, neighborhood parks or part of a hike & bike
trail. Raised crosswalks shall not be used arbitrarily in attempt to satisfy minor
treatment for exceeding maximum straight sections, but only when there is a
high potential for pedestrian traffic such as for hike & bike crossings, or near
parks or amenity centers.
d. Choker – a horizontal extension of the curb into the street resulting in a
narrower roadway section (a minimum of 24 ft to remain). They shall be
between 12 ft and 20 ft in length and designed with a mountable curb. Chokers
shall include stamped and stained (integral color) concrete of a pattern and
color that is cohesive with the neighborhood. Pavers shall be allowed with
approval by the Director of Engineering Services and may include a
maintenance agreement with the HOA. Chokers shall only be allowed adjacent
to open space lots or residential lots greater than 60 ft in width when centered
on lot lines so as not to hinder residential lot access.
e. Median Island – a raised island in the middle of a roadway along a street
centerline. The raised island shall be 3 to 3.5 inches in height with a mountable
curb, a minimum of 4 feet in width (as measured from back of curb) and a
minimum of 20 in length. Median Islands shall include stamped and stained
(integral color) concrete of a pattern and color that is cohesive with the
neighborhood. Pavers shall be allowed with approval by the Director of
Engineering Services and may include a maintenance agreement with the
HOA. Median Islands shall only be allowed adjacent to open spaces (both
sides), and shall require 24 foot lanes on either side (face of curb to face of
curb).
2. Major Traffic Calming Treatments – required in combination with minor street
treatments, but when the straight tangent section exceeds 2000 feet.
a. Mini Residential Traffic Circle –a mini traffic circle shall be allowed on
residential roadways to satisfy a major traffic calming treatment and shall
include the following:
Design shall follow Town detail for a Mini Traffic Circle
Driveway/access restrictions shall be placed on the final plat for all
residential lots that are adjacent to traffic circle.
b. Mini Roundabout - a mini roundabout following criteria as listed in FHWA
technical bulletin and similar features as identified in section 4.02.F. shall be
allowed on residential roadways (2LN) and shall include the following:
Common areas shall be provided adjacent to the roundabout up to the
pedestrian crossings on minor legs of intersection and for the full length of
the adjacent lot on the major leg of intersection.
Roundabouts shall be used in lieu of a traffic circles when one of the
intersection legs is a significantly dominant route over the other leg.
Advisory Note: Dominant routes can be subjective, but are mostly considered for
entries into a development, or major routes to schools or neighborhood parks.
Ordinance No. 2020-54, Page 20
ENGINEERING DESIGN STANDARDS
4-19
4.03. Median, Left-Turn Lane, Right-Turn Lane, Deceleration Lane, and Island Design
A. Required Median Openings and Left-Turn Lanes:
1. Median openings on divided thoroughfares shall be required at all street
intersections. Median openings may be constructed to serve non-residential drives
provided that the minimum spacing requirements listed are met. Left-turn lanes
shall be provided at all median openings.
2. All non-residential lots on a divided thoroughfare shall have direct or indirect
access to a median opening. Indirect access shall be provided through a series of
fire lane and access easements. Multifamily developments, on a divided
thoroughfare, shall have direct access to a median opening. Median openings for
street intersections and non-residential driveways may be moved at the discretion
of the Town to facilitate traffic flow as long as minimum distances are maintained
as per Sections 4.03.B.4 and 4.03.B.5.
B. Minimum Left-Turn, Transition Length, and Median Opening Width, Location, and
Spacing Requirements:
1. Left-Turn Lane Storage:
a. All left-turn storage areas on divided thoroughfares shall be ten feet (10’) wide.
b. Storage requirements listed in Table 4.5 are absolute minimums. Storage
requirements may be increased by the Town based upon actual and projected
traffic demands of the properties, which will be served by the left-turn lane.
c. Left-turn lanes will be delineated by using buttons.
d. Stamped and stained concrete shall be used in the median rather than grass
when the median width measured from back of curb to back of curb is a
distance of four feet (4’) or less.
2. Transition Length – The transition specifications for left-turn lane entrance areas
are specified in Table 4.5. The variables used for the specification are shown in
Figure 4.5.
3. Median Openings:
a. Median openings at intersections shall accommodate all turning paths and
crosswalks.
b. The length of mid-block median openings shall be between sixty feet (60’) and
seventy feet (70’). Median openings may be up to eighty feet (80’) long where
necessary to accommodate turning paths and crosswalks, subject to approval
by the Director of Engineering or their designee.
4. Minimum Spacing Between an Intersection and the First Mid-Block Median
Opening on Divided Thoroughfares – The minimum distance to the first mid-block
median opening along 4 or 6 lane thoroughfares that are immediately downstream
from an intersection with a 4 or 6 lane thoroughfare are shown in Figure 4.6. These
distances vary from three hundred fifty feet (350’) to four hundred twenty-five feet
(425’) nose to nose depending on the thoroughfare type and the type of mid-block
opening.
Ordinance No. 2020-54, Page 21
ENGINEERING DESIGN STANDARDS
4-20
5. Minimum Distance Between Mid-Block Median Openings for 3L, 2LC, 2LN, and
2LRN Thoroughfares and Driveways along Divided Thoroughfares – The minimum
distance between median openings on a 4 or 6 lane thoroughfare where left-turn
storage is provided in both directions for 3L, 2LC, 2LN, and 2LRN intersecting
thoroughfares and driveways is shown in Figure 4.7. The distances shown are
measured nose to nose. Refer to Tables 4.8-4.10 for driveway design
requirements.
TABLE 4.5: Minimum Left-Turn Design Requirements
Type of
Thoroughfare
On
Type of
Thoroughfare
At
Turn Lane
Width(s) (ft)
Length of
Full-Width
Turn Lane
(ft)
Transition
Specifications
Length
(ft)
R1(ft) R2(ft)
6LD, 4/6LD 4 or 6 lane 10(1) 150, 250(2) 200 505 505
4LD, 4LRD 4 or 6 lane 10 150 100 250 250
4 or 6 lane 3L, 2LC 10 150 100 250 250
4 or 6 lane 2LN, 2LRN 10 100(3) 100 250 250
4 or 6 lane Non-Residential
Driveway
10 150 100 250 250
NTTA Service
Road
All Types 10 150, 250(2) 200 505 505
(1) Double Left-Turn Lanes
(2) 150’ – Inside Left-Turn Lane; 250’ – Outside Left-Turn Lane
(3) 150’ stacking shall be required for gated communities
FIGURE 4.5: Typical Left-Turn Lane Dimensions
Ordinance No. 2020-54, Page 22
ENGINEERING DESIGN STANDARDS
4-21
FIGURE 4.6: Minimum Spacing Between an Intersection and the First Mid-Block Median
Opening on a Divided Thoroughfare
Ordinance No. 2020-54, Page 23
ENGINEERING DESIGN STANDARDS
4-22
FIGURE 4.7: Minimum Distance Between Mid-Block Median Openings on a 4 or 6 Lane
Thoroughfare
6. Medians Where No Left-Turn Lane is Needed:
a. The minimum length of median shall be the sum of the required left-turn
storage, transition length, ten-foot (10’) tangent and length of median nose.
This requirement is reflected in Figure 4.8. This allowed, provided that access
is not compromised for vacant property on the opposite side of the street.
FIGURE 4.8: Minimum Length of Median Where No Left-Turn Lane is Needed
Ordinance No. 2020-54, Page 24
ENGINEERING DESIGN STANDARDS
4-23
b. If left-turn storage is not required in either direction, and the median is simply
a spacer between two median openings, the minimum length of the spacer
must be one hundred feet (100’). This is reflected in Figure 4.9.
FIGURE 4.9: Minimum Spacer Length
c. If a driveway is not served by a median opening, then seventy-five feet (75’) of
separation shall be provided from the edge of driveway to the nearest median
opening.
7. Medians on Public Street Entrances to Developments:
a. Medians installed on undivided streets at entrances to subdivisions for
aesthetic or any other purpose shall be a minimum of thirteen feet (13’) wide
and one hundred feet (100’) long. See Figure 4.1 for Divided Residential
Subdivision Entrance cross section.
b. In areas where a divided subdivision entry is constructed, the transition to the
normal residential street width shall begin upstream or downstream of the first
street intersection. No part of the transition shall occur within the intersection.
c. Alternative design standards may be required for these types of subdivision
entries if they are located within special overlay districts defined by the Town.
C. Minimum Right-Turn Storage and Transition Length:
1. Right-Turn Lane Storage:
a. Right-turn lanes shall be required at every street intersection along 4 or 6 lane
thoroughfares at the time of construction of each intersection.
b. All right-turn storage areas shall be eleven feet (11’) wide (except on 4LRD
thoroughfares where a minimum width of ten feet (10’) will be allowed).
c. An additional ten feet (10’) of ROW shall be provided with right-turn lanes.
d. Storage requirements listed in Table 4.6 are absolute minimums. Storage
requirements may increase based upon actual and projected traffic demands.
e. A tangent section of ten feet (10’) shall be provided from the receding driveway
curb return to the transition of a right-turn lane.
2. Transition Length – The transition specifications for right-turn lane entrance areas
are specified in Table 4.6. The variables used for the specification are shown in
Figure 4.10.
Ordinance No. 2020-54, Page 25
ENGINEERING DESIGN STANDARDS
4-24
TABLE 4.6: Minimum Right-Turn Lane Design Requirements
Type of
Thoroughfare
On
Type of
Thoroughfare
At
Turn Lane
Width (ft)
Storage
Length of Full-
Width Turn
Lane (ft)(1)
Transition
Specifications(2)
Length
(ft)
R1
(ft)
R2
(ft)
6LD, 4/6LD 4 or 6 lane 11 200 150 515 515
4LD 4 or 6 lane 11 150 150 515 515
6LD, 4/6LD,
4LD
3L, 2LC 11 150 110 280 280
6LD, 4/6LD,
4LD
2LN, 2LRN 11 100 110 280 280
4LRD All Types 10 100 110 280 280
NTTA
Service
Road
All Types 11 200 150 515 515
(1) Measured from the intersection thoroughfare ROW.
(2) No driveways are permitted within the transition area.
FIGURE 4.10: Typical Right-Turn/Deceleration Lane Dimensions
Ordinance No. 2020-54, Page 26
ENGINEERING DESIGN STANDARDS
4-25
D. Minimum Deceleration Lane Storage and Transition Length:
1. Deceleration Lane Storage:
a. Deceleration lanes shall be provided at driveways on 4 or 6 lane thoroughfares
where required by Section 4.04.(A.4).
b. All deceleration lane storage areas shall be eleven feet (11’) wide.
c. Ten feet (10’) of street easement, adjacent to ROW, shall be provided with
deceleration lanes.
d. Storage requirements listed in Table 4.7 are absolute minimums. Storage
requirements may increase based upon actual and projected traffic demands.
e. A tangent section of ten feet (10’) shall be provided from the preceding
driveway curb return to the transition of a deceleration lane.
2. Transition Length – The transition specifications for deceleration lane entrance
areas are specified in Table 4.7. The variables used for the specification are shown
in Figure 4.10.
TABLE 4.7: Minimum Deceleration Lane Design Requirements
Type of
Thoroughfare On
Type of
Thoroughfare At
Turn
Lane
Width(s)
(ft)
Length of Full-
Width Turn
Lane (ft)(1)
Transition
Specifications
Length
(ft)
R1
(ft)
R2
(ft)
6LD, 4/6LD Non-Residential
Driveway
11 80 110 280 280
4LD Non-Residential
Driveway 11 60 110 280 280
4LRD Non-Residential
Driveway 10 60 110 280 280
NTTA Service
Road
Non-Residential
Driveway 11 80 110 280 280
(1) Measured from the curb return of the driveway
Ordinance No. 2020-54, Page 27
ENGINEERING DESIGN STANDARDS
4-26
E. Cost of Median Openings and Turn Lanes:
1. Median openings, left-turn lanes, and right-turn lanes constructed for residential
streets and/or subdivision entrances shall be the responsibility of the developer
and shall be paved to Town standards and inspected by the Town.
2. Median openings, left-turn lanes and declaration lanes for multifamily and non-
residential developments shall be the responsibility of the developer and shall be
paved to Town standards and inspected by the Town.
3. The Town shall require escrow of funds for such future improvements prior to final
acceptance or Certificate of Occupancy, whichever occurs first. The escrow shall
include all construction costs; engineering (7% of construction cost) and inspection
(3% of construction cost).
4.04. Driveway Design
A. Introduction – Driveway design standards are needed to provide safe and efficient
vehicular access to and from the public street system, to provide public street capacity
for accommodating peak traffic volumes of public streets, to maintain smooth traffic
flow, and to maintain street ROW and drainage. The intent of driveway design
standards is to achieve the following:
1. Prohibit the indiscriminate location and spacing of driveways while maintaining
reasonable vehicular access to and from the public street system.
2. Reduce conflicting turning movements and congestion thereby reducing vehicular
accidents.
3. Maintain and enhance a positive image for the attraction of new, high quality,
residential and non-residential development in the Town.
4. Provide right-turn and deceleration lanes for all streets and driveways along all 4
or 6 lane thoroughfares.
B. Definition of Driveway Types:
1. Residential Driveway – Provides access to a single-family residence, duplex, or
multifamily building containing four or fewer dwelling units. These drives shall
intersect 2LN, and 2LRN roadways only.
2. Non-residential Driveway:
a. Commercial Driveway – Provides access to an office, retail or institutional
building, or multifamily building having more than four dwelling units. It is
anticipated that such buildings will have incidental truck service. Commercial
drives shall access 3, 4 or 6 lane thoroughfares only.
b. Industrial Driveway – Serves truck movements to and from loading areas of an
industrial facility, manufacturing, warehouse, or truck terminal. A retail
development may have one or more driveways specially designed, signed, and
located to provide access for trucks. These types of driveways shall be
considered industrial driveways. Driveways to industrial plants whose principle
function is to serve administrative or employee parking lots shall be considered
Ordinance No. 2020-54, Page 28
ENGINEERING DESIGN STANDARDS
4-27
commercial driveways. Industrial drives shall not access Residential 2LC, 2LN,
or 2LRN thoroughfares.
3. Standard Driveway – Provides two-way access at a single, undivided curb
opening.
4. One-Way Driveway – Provides inbound or outbound access and can only be
permitted when the orientation of on-site circulation and parking layout clearly
utilize the driveway for one-way movements.
5. High Capacity Driveways – Intended to provide two-way access with geometric
provisions which more adequately respond to greater driveway volumes and/or
access limitations than standard driveways. These provisions include increased
width and/or internal storage. Median divider and/or deceleration lanes may also
be required.
C. General Design Parameters:
1. The centerline angle for a driveway approach shall be ninety degrees (90°) to the
street curb line for all driveways.
2. Driveways shall not be permitted in the transition area of any right-turn lane or
deceleration lane.
3. Driveways that intersect at a mid-block median shall have the driveway centerline
intersect with the midpoint of a median opening (measured nose-to-nose).
4. Driveway restrictions can be required by the Director of Engineering to ensure
adequate circulation.
5. Driveway elevations at the ROW line shall be a minimum of six inches (6”) above
the street gutter. A residential driveway that intersects an alley shall be three
inches (3”) above the edge of the alley pavement at the ROW line.
6. Cross access is required between adjacent retail, office and commercial
properties.
7. Driveway grades in a fire lane shall not exceed six percent (6%) either
longitudinally or four percent (4%) cross slope to accommodate emergency vehicle
access.
8. Differential grades on driveways shall not exceed twelve percent (12%).
Differential grades on commercial driveways with fire lanes shall not exceed six
percent (6%).
9. All driveway approaches within right-of-way shall match the street pavement
thickness, subgrade, and moisture conditioning depth. Steel reinforcement shall
meet current street standards.
D. Driveway Width – The width of a driveway refers to the width of pavement at the
property line and is measured where the curb return radii ends perpendicular to the
street curb or edge of pavement. The minimum and maximum widths of driveways are
listed in Table 4.8.
Ordinance No. 2020-54, Page 29
ENGINEERING DESIGN STANDARDS
4-28
TABLE 4.8: Minimum and Maximum Driveway Widths
Driveway Type Land Use Width in Feet (face to face)
Minimum (ft) Maximum (ft)
Standard Drive
Residential 10 24
Commercial/Multifamily 24 33
Industrial 30 40
One-Way Drive
Residential (circular) 10 16
Commercial 16 24
Industrial 24 24
Divided High Capacity Drive for
Non-residential Uses
Entrance Lane 16 24
Exit : Two 24 24
Three 30 33
Driveway Medians (non-residential/multifamily uses) 4 11
Notes:
1. A residential driveway width of thirty-two feet (32’) may be allowed to an alley if the garage
faces onto the alley.
2. The maximum width for service station driveways shall be thirty-six feet (36’).
3. Driveways that serve as a fire lane shall be a minimum of twenty-four feet (24’) in width.
E. Driveway Radius:
1. All driveways intersecting dedicated streets shall be built with a circular curb radius
connecting the six-inch (6”) raised curb of the roadway to the design width
pavement of the driveway.
2. Driveway radii shall fall entirely within the subject property so as to begin at the
street curb at the extension of the property line. Commercial driveways may
encroach past property line if deceleration lanes are required and proper
easements have been acquired.
3. Table 4.8 presents the minimum and/or maximum standards to be applied in
designing and locating driveways on public streets.
4. High capacity driveways shall meet the same standards as those defined in Table
4.8.
F. Driveway Spacing:
1. Driveways shall be spaced at distances sufficient to ensure that conflicting
movements do not overlap at adjacent driveways or at offset driveways on
opposite sides of the street.
Ordinance No. 2020-54, Page 30
ENGINEERING DESIGN STANDARDS
4-29
2. Spacing between driveways should be measured along the property line from the
edge of one driveway to the closest edge of the next driveway and not from
centerline to centerline.
3. The minimum spacing between driveways is a function of street classification and
shall be as listed in Table 4.9.
4. The driveway spacing from a railroad crossing shall be a minimum of fifty feet (50’)
from the railroad ROW.
TABLE 4.9: Driveway Design Requirements
Criteria Thoroughfare
Classification
Residential
Driveway (ft)
Commercial/Multifamily
Driveway (ft)
Industrial
Driveway (ft)
Driveway
Curb Radius
Major: 6LD, 4/6
LD
-- 20-30 20-30
Minor: 4LD,
4LRD
-- 20-30 20-30
3L, Commercial
2LC
-- 20-30 20-30
Residential 2LC 5-10 20 --
Local: 2LN,
2LRN
5-10 -- --
Minimum
Driveway
Spacing
Along
Roadway
(edge to
edge)
Major: 6LD, 4/6
LD
-- 240 240
Minor: 4LD,
4LRD
-- 200 200
3L, Commercial
2LC
-- 90 90
Residential 2LC 20 Max of 1 drive --
Local: 2LN,
2LRN
20 -- --
Minimum
Distance
between
Intersection
and Driveway
(driveway
edge to
intersecting
ROW)(1)
Major: 6LD, 4/6
LD
-- 75/100 75/100
Minor: 4LD,
4LRD
-- 75/100 75/100
3L, Commercial
2LC
-- 50/50 50/50
Residential 2LC 20/20 100/100 --
Local: 2LN,
2LRN
10/10 from
tangent to
edge of drive
-- --
(1) Upstream/downstream distance to intersection. (See Figure 4.11)
5. To minimize the number of curb cuts along public roadways, joint or shared access
is encouraged for residential driveways and required for commercial driveways.
Shared access drives shall conform to the following standards.
a. Residential: no less than ten feet (10’) of the total driveway width (20’ min. –
24’ max.) shall be located on each property.
b. Commercial/Industrial: no less than twelve feet (12’) of the total driveway width
(24’ min. – 36’ max.) shall be located on each property.
Ordinance No. 2020-54, Page 31
ENGINEERING DESIGN STANDARDS
4-30
c. Joint access drives for commercial/industrial developments shall include full
drive width and access pavement and be built at the same time as
development.
d. The spacing and location of driveways shall be related to both existing adjacent
driveways and those shown on approved development plans.
FIGURE 4.11: Distance Between Driveway and Intersection
G. Distance Between Driveway and Intersection:
1. Adequate distance between cross street intersections and access drives shall be
provided to ensure intersection/driveway conflict areas are minimized.
2. Table 4.9 defines the upstream and downstream distance from an intersection as
a function of street classification.
H. Deceleration Lanes:
1. Deceleration lanes for right-turns into driveways will ease the negative impact a
driveway will have on traffic flow, driveway conflict points and safety due to speed
differential.
2. One driveway may be located within the full-width storage portion of a right-turn
lane at a public street intersection. Such a driveway shall be located a minimum of
seventy-five feet (75’) in advance of the intersecting ROW, and a minimum of fifty
feet (50’) of storage length shall be provided in advance of the driveway (see Figure
4.11).
3. The developer shall be responsible for the design, ROW adjustment of utilities, and
construction costs of any auxiliary and deceleration lane required as a condition of
a driveway permit.
4. Refer to Table 4.7 for deceleration lane design standards.
Ordinance No. 2020-54, Page 32
ENGINEERING DESIGN STANDARDS
4-31
I. Driveway Storage Lengths:
1. On-site internal storage shall be provided at all non-residential and multifamily
driveways for queuing of vehicles off-street, to minimize congestion, and increase
safety both on the public street and within the driveway.
2. Internal storage requirements shall be based on the total number of parking spaces
accessible by the affected driveway.
3. Internal storage length shall be measured from the ROW line to the first aisle or
parking stall that intersects with inbound traffic. If inbound traffic and outbound
traffic are separated by a median for the required storage distance, a parking aisle
can connect to the outbound portion of the driveway closer to the street (as long
as a minimum of twenty-five feet (25’) is maintained between the aisle and the
ROW line).
4. Table 4.10 presents internal storage requirements.
TABLE 4.10: Minimum Driveway Storage Lengths
Parking Spaces
per Driveway
Storage Required (ft)
Multifamily/Commercial Uses Industrial Land Uses
Non-Median
Opening
Median
Opening
Non-Median
Opening
Median
Opening
Less than 25 25 25 25 25
25-50 25 40 25 40
51-100 25 40 40 40
101-200 40 80 40 60
More than 200 100 100 40 100
J. Driveway for Gated Developments:
1. Residential/Multifamily:
a. Gated developments shall have a median divided street that will allow for a
vehicular turn-around prior to the gate in the event that access is denied.
b. The turn-around shall be a minimum of eighteen feet (18’) in width.
c. Entry gates shall be set back from the ROW a minimum of one hundred thirty-
five feet (135’) to provide stacking space to the card reader (or first stop) of a
minimum of one hundred feet (100’) to allow the longest queue of vehicles
expected to access the gate.
d. The drives shall be a minimum of twenty-four feet (24’) in width with driveway
curb radii of thirty feet (30’). See Figure 4.12.
e. The hinge point of the gate shall be a minimum of eighteen inches (18”) behind
the back of the curb. The gate shall open to twenty-four inches (24”) behind
the back of curb.
f. Gates shall be equipped with both Opticom and Knox-Box for emergency
access.
g. Gates shall not encroach on sidewalks.
2. Other Non-Residential:
Ordinance No. 2020-54, Page 33
ENGINEERING DESIGN STANDARDS
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a. Gated developments shall have a median separating ingress and egress traffic
flow allowing for a vehicular turn-around prior to the gate in the event that
access is denied.
b. The turn-around shall be a minimum of eighteen feet (18’) in width.
c. Entry gates shall be set back from the ROW or fire lane a minimum of seventy-
five feet (75’) to provide stacking space to the card reader (or first stop) of a
minimum of forty feet (40’) to allow the longest queue of vehicles expected to
access the gate.
d. The drives shall be a minimum of twenty-four feet (24’) in width with driveway
curb radii of thirty feet (30’). See Figure 4.12.
e. The hinge point of the gate shall be a minimum of eighteen inches (18”) behind
the back of the curb. The gate shall open to twenty-four inches (24”) behind
the back of curb.
f. Gates shall be equipped with both Opticom and Knox-Box for emergency
access.
g. Gates shall not encroach on sidewalks.
h. Alternate standards may be required based on the results of a Traffic Impact
Analysis (TIA).
3. Individual Gated Single-Family Residences – Gate shall have a minimum setback
of twenty feet (20’) from the ROW to provide space for at least one vehicle to wait
while accessing the gate.
Ordinance No. 2020-54, Page 34
ENGINEERING DESIGN STANDARDS
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FIGURE 4.12: Gated Entrance Detail
K. Nonconforming Driveways:
1. All nonconforming driveways on a lot, tract, parcel or site shall be allowed to remain
in place until the occurrence of one or more of the following events:
a. A change in use, or an increase in intensity of use, occurs such that the site
requires a ten percent (10%) increase in required parking spaces.
b. Addition of parking spaces.
c. Any modification that changes the design or function of the existing driveway.
d. The addition of a median opening on the public street by a developer. All
driveways that are served by the new median opening shall comply with the
requirements of these standards.
2. Upon the occurrence of the events described, the nonconforming status of the
driveway shall cease and the driveway must be either reconstructed in accordance
with this ordinance or eliminated.
4.05. Alley Design
A. Alley Intersections:
1. Alleys shall only intersect 3L, Residential 2LC, 2LN, and 2LRN thoroughfares.
Ordinance No. 2020-54, Page 35
ENGINEERING DESIGN STANDARDS
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2. If an alley and a Commercial 2LC, or higher-class thoroughfare, are parallel and
separated only by a landscape buffer, the alley shall turn away from that
thoroughfare not less than one subdivision lot width or a minimum of forty feet
(40’) (whichever is greater) from the cross street as shown in Figure 4.20.
3. The ROW line of all alley intersections shall be a minimum of forty feet (40’) or
one subdivision lot width (whichever is greater) away from the ROW line of the
nearest street intersection. See Figure 4.13.
4. All alley intersections with streets shall be perpendicular or radial, within a five-
degree (5°) tolerance, at the intersection of the ROW lines.
5. Alley offsets along residential streets shall be less than fifteen feet (15’) or
greater than seventy-five feet (75’) measured from alley centerline to alley
centerline.
6. Alleys shall not align with existing streets such as to create a four-way
intersection. Alleys shall be offset from such a street or driveway by a minimum
of seventy-five feet (75’) measured from edge of alley to edge of street or
driveway.
7. Alleys shall not align across from future streets to create an intersection.
8. Internal alley to alley intersections (if not lined up) shall be offset, from the
centerline, a minimum of one hundred feet (100’).
9. Alleys that intersect at “elbow” street intersections shall not intersect within thirty
degrees (30°) of the centerline of the adjacent streets. See Figure 4.14.
10. Alleys shall not intersect with a roundabout.
FIGURE 4.13: Minimum Distance from Intersection for Parallel Alley
Ordinance No. 2020-54, Page 36
ENGINEERING DESIGN STANDARDS
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FIGURE 4.14: Alley Intersecting an Elbow
11. Internal alley intersections shall consist of no more than three (3) alley approaches.
12. No permanent dead-end alley shall be permitted in new subdivisions. Alleys shall
connect and/or be aligned with alleys in adjacent subdivisions.
13. The radius of alley pavement at street intersections shall not be less than fifteen
feet (15’). At the intersection of two alleys, the radius of the alley ROW is
dependent upon the alley ROW intersection angle as listed in Table 4.11. At the
intersection of two alleys, the radius of the alley pavement shall be two feet (2’)
greater than the radius of the alley ROW. See Figure 4.15.
FIGURE 4.15: Alley to Alley Intersection
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ENGINEERING DESIGN STANDARDS
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B. Alley Radius – Alley radii at street intersections shall not be less than fifteen feet (15’).
See Figure 4.16.
1. Alley Intersecting Alley Radius – The radius shall be measured from the ROW
and vary based upon the alley ROW intersection angle listed in Table 4.11.
TABLE 4.11: Alley Intersecting Alley Radius
Alley ROW Intersection Angle Minimum Required ROW Radius
(ft)
1°-40° 70
41°-70° 50
71°-90° 40
> 90° 50
C. Alley ROW Width – The alley ROW width shall be eighteen feet (18) for residential
alleys and twenty feet (20’) for non-residential alleys.
D. Alley Pavement Width – The alley pavement width shall be twelve feet (12’) for
residential alleys and twelve feet (12’) for non-residential alleys, except near street
intersections as shown in Figure 4.16.
E. Alley Pavement Thickness: The thickness shall be a minimum of 6” with pavement
strength and reinforcement as required in Section 4.02.(B.5).
FIGURE 4.16: Alley Dimensions
F. Alley Length – Alleys shall not exceed eight hundred feet (800’) in length without an
intermediate connection to a residential street.
G. Rear Alley Frontage – The minimum alley rear frontage shall be twenty feet (20’).
H. Alley as a Fire Lane – An alley that also serves the purpose of a fire lane shall be
constructed to the standards of a fire lane as required by the Fire Department. These
standards include, but are not limited to, a minimum pavement width of twenty-four
feet (24’) and a minimum radius of alley pavement of thirty feet (30’) at street
intersections. Right-of-way shall be 30 feet in width for 24 foot alley sections.
I. Alley Speed Limits – The speed limit in alleys shall be ten miles per hour (10 MPH).
Ordinance No. 2020-54, Page 38
ENGINEERING DESIGN STANDARDS
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J. Alley Visibility Obstructions:
1. No Fence, wall, screen, sign, structure, or foliage of hedges, trees, bushes, or
shrubs shall be erected, planted or maintained in any alley ROW.
2. Foliage of hedges, trees, bushes, and shrubs planted adjacent to the alleys ROW
shall be maintained such that the minimum overhang or encroachment shall be
fourteen feet (14’) above the alley surface one foot (1’) outside the edge of the
pavement.
K. Alley Grade:
1. Alleys shall have a maximum grade of six percent (6%) and a minimum of six-
tenths percent (0.60%). Steeper grades may be permitted where required by
topographical and/or natural features, as approved by the Director of Engineering
Services.
2. Alleys shall maintain a maximum cross-slope of two percent (2%) at the
intersection of the adjacent sidewalk.
L. Vertical Curves in Alleys – Vertical curves in alleys shall be used in order to provide a
design which is safe, comfortable in operation, pleasing in appearance and adequate
for drainage. Vertical curve alignment shall also provide stopping sight distance in all
cases based on a design speed of twenty miles per hour (20 MPH).
M. Alley Screening Walls – The area between screening walls and alleys shall be paved
and graded to drain to the invert.
Ordinance No. 2020-54, Page 39
ENGINEERING DESIGN STANDARDS
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4.06. Frontage Road Design (Non-TxDOT)
A. Frontage roads are typically found adjacent to existing or planned freeway type
facilities.
B. Frontage roads are considered 6LD thoroughfares and should be designed to the
6LD standards set forth in this document.
C. Access to frontage roads shall also conform to the standards set forth for 6LD
thoroughfares. In addition, the following access restrictions apply to frontage road
design:
1. Exit Ramp Restrictions:
a. No driveway shall be located less than fifty feet (50’) in advance of the
concrete curb gore of an exit ramp.
b. No driveway shall be located less than four hundred feet (400’) beyond the
striped gore of an exit ramp (designated as the point where the striping of the
exit ramp lane and the through lane converge), measured from the edge of
the driveway.
2. Entrance Ramp Restrictions:
a. No driveway shall be located less than two hundred feet (200’) in advance of
the striped gore of an entrance ramp (designated as the point where the
striping of the entrance ramp lane and the through lane diverge), measured
from the edge of the driveway.
b. No driveway shall be located less than fifty feet (50’) beyond the concrete curb
gore of an entrance ramp.
4.07. Bridge and Bridge-Class Culvert Design
All bridges and bridge-class culverts in Prosper shall be designed at a minimum in
accordance with the latest edition of the AASHTO Standard Specifications For Highway
Bridges and the TxDOT Bridge Design Manual. Specifications for bridge construction shall
be in accordance with the TxDOT Standard Specifications for Construction and
Maintenance of Highways, Streets, and Bridges (edition to be used shall be determined
by the Town of Prosper). All bridge railing shall be in accordance with the latest edition of
the TxDOT Bridge Railing Manual and shall be approved in the NCHRP Report 350. All
bridge rails shall be appropriately rated railing based on design conditions. Guardrail, end
treatments, or other features associated with bridge construction shall be in accordance
with the latest edition of the AASHTO Policy on Geometric Design of Highways and
Streets, the AASHTO Roadside Design Guide, and current TxDOT Standards.
The local standards that shall govern the applicable elements of the design can be
found in Table 4.12
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ENGINEERING DESIGN STANDARDS
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TABLE 4.12: Elements of Bridge Design Standards
Element of Bridge Design Standard of Design
Reinforcing Steel Epoxy coating required
Travel Lane Width 12’ minimum
Offset to Face of Rail 2’ minimum
Where no sidewalk is present, shoulders shall be
flush with the roadway slab.
Sidewalk Width 6’ minimum, 8’-10’ if designated hike & bike
corridor
Parkways Culverts to be extended to the ultimate right-of-
way and graded to the standard parkway
Bridge Rail TxDOT T401 for vehicular protection only
TxDOT T401 for vehicular/pedestrian separation
Separation rail shall be used on all major and
minor arterial bridges; it shall not be required on
collectors or local streets, or on culverts where
the sidewalk is not located adjacent to the back
of curb
TxDOT C402 for vehicular and pedestrian
protection
TxDOT PR1 for pedestrian protection only
Parapet Wall with Rail Finish Stone facia all vertical surfaces, Ashlar Stone or
similar
Stain all vertical surfaces, color(s) shall be approved
by the Director of Engineering
Pedestrian Rail Finish Paint all surfaces with industrial-grade exterior
paint, color shall be approved by the Director of
Engineering
Drainage All roadway drainage shall be carried to the
bridge ends and collected in closed storm sewer
system. If deck drains are required they shall
discharge to downspout and a properly designed
splash basin or closed storm sewer system to
minimize erosion. Drainage shall not discharge
against any part of the structure.
Lighting Spacing based on approved photometric plan,
standard fixtures, both directions
Decorative lighting options shall be approved by
the Director of Engineering
Conduit Required fiber optic and street lighting conduit
shall be fastened to the exterior slab overhang.
Aesthetic Variations All aesthetic variations shall be consistent with
surrounding features and shall be approved by
the Director of Engineering.
Ordinance No. 2020-54, Page 41
ENGINEERING DESIGN STANDARDS
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4.08. Pedestrian Facilities
A. All pedestrian facilities must conform to the following current requirements and shall
be in accordance with the Town’s Hike & Bike Trail system, Zoning and Town’s
Comprehensive Master Plan or as amended through ordinance.
B. Pedestrian Design Guidelines include the current edition of the following:
1. Texas Accessibility Standards (TAS).
2. Americans with Disabilities Act (ADA) Standards.
3. Proposed Accessibility Guidelines for Pedestrian Facilities in Public Right-of-Way
(PROWAG).
4. Texas Manual on Uniform Traffic Control Devices (TMUTCD).
C. Sidewalks
The purpose of the public sidewalk is to provide a safe area for pedestrians. Town of
Prosper policy provides that sidewalks are to be constructed with the paving of streets
or building construction unless deferred by the Director of Engineering. Sidewalks
constructed as part of a new development or re-development are considered public
facilities and shall be constructed according to the requirements outlined in this
section.
A sidewalk is the paved area in a street ROW between the curb lines or the edge of
pavement of the roadway and the adjacent property lines for the use of pedestrians.
The Town of Prosper considers a sidewalk to be an “accessible route” as specified in
Section 4.3 of the Texas Accessibility Standards (TAS) and considers a public
sidewalk a “facility” under the TAS and the U.S. Department of Justice Americans with
Disabilities Act (ADA) regulations at 28 C.F.R. Part 35 unless exempted by the Director
of Engineering. Compliance with these regulations shall be the responsibility of the
owner/developer.
1. Design:
For pedestrian comfort, it is desirable to provide buffer space between the sidewalk
and the back of curb of at least 3 feet (3’). All new sidewalks in the Town of Prosper
shall be placed 1 foot (1’) inside the ROW line unless approved by the Director of
Engineering.
Sidewalks shall conform to all current TAS, ADA requirements, and in accordance
with this section, and if there is a conflict among those standards, the more
stringent shall govern. The maximum running grade (longitudinal slope) of the
sidewalk shall not exceed 5% unless approved by the Director of Engineering. The
maximum cross-fall (cross slope) of the sidewalk shall not exceed 2%.
Sidewalk widths vary depending on the roadway classification. A concrete
sidewalk 6 feet in width is required on all Regional Freeways, Arterial
thoroughfares and collector roadways. A concrete sidewalk 5 feet in width is
required along both sides of all residential roadways. See Table 4.13 for sidewalk
widths on all street types. The sidewalks shall be located within the street ROW
unless pre-existing physical encroachments (e.g., utility infrastructure or trees)
dictate otherwise. Sidewalks may be allowed in landscape areas and pedestrian
access easements with the approval of the Director of Engineering. Sidewalks
along arterial roadways shall be done in manner to follow the Town of Prosper’s
Thoroughfare landscaping requirements as depicted in the Zoning Ordinance.
Ordinance No. 2020-54, Page 42
ENGINEERING DESIGN STANDARDS
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Sidewalks and parkways (curb to ROW) shall be graded at 2% above the top of
the street curb.
TABLE: 4.13: Sidewalk Widths
Street Type Sidewalk Width
Arterial 6 ft
Collector 6 ft
Residential 5 ft
2. Hike & Bike Trails:
For pedestrian comfort, it is desirable to provide buffer space between the sidewalk
and the back of curb of at least three feet (3’). All new sidewalks in the Town of
Prosper shall be placed one foot (1’) inside the ROW line unless approved by the
Director of Engineering.
Sidewalks shall conform to all current TAS, ADA requirements, and in accordance
with this section, and if there is a conflict among those standards, the more
stringent shall govern. The maximum running grade (longitudinal slope) of the
sidewalk shall not exceed 5% unless approved by the Director of Engineering. The
maximum cross-fall (cross slope) of the sidewalk shall not exceed 2%.
Sidewalk widths vary depending on the roadway classification. A concrete
sidewalk six feet (6’) in width is required on all Regional Freeways, Arterial
thoroughfares and collector roadways. A concrete sidewalk five feet (5’) in width
is required along both sides of all residential roadways. The sidewalks shall be
located within the street ROW unless pre-existing physical encroachments (e.g.,
utility infrastructure or trees) dictate otherwise. Sidewalks may be allowed in
landscape areas and pedestrian access easements with the approval of the
Director of Engineering. Sidewalks along arterial roadways shall be done in
manner to follow the Town of Prosper’s Thoroughfare landscaping requirements
as depicted in the Zoning Ordinance. Sidewalks and parkways (curb to ROW)
shall be graded at 2% above the top of the street curb.
3. Sidewalks on Bridges:
a. All street bridges shall have a sidewalk constructed on each side of the bridge.
The sidewalk shall be a minimum of six feet (6’) wide with a parapet wall that
is separated from the travel lane by an eighteen-inch (18”) shoulder.
b. A standard pedestrian bridge rail protecting the sidewalk shall be provided on
the outside edge of the bridge.
4. Hike & Bike Trail Under Bridges – When new bridges are built as a part of the
construction of a roadway or the reconstruction of a roadway and a hike and bike
trail crossing as depicted on the Town’s Master Hike & Bike Trail Plans, the hike
and bike trail will be built as a part of the embankment design underneath the
bridge structure
5. Sidewalks on Culverts – All culvert crossings shall have a sidewalk constructed on
each side of the culvert. The sidewalk shall be a minimum of six feet (6’) wide with
a standard pedestrian hand rail as shown in Figure 4.18 provided on the outside
edge of the culvert. Parapet wall may be required by the Engineering Department.
Ordinance No. 2020-54, Page 43
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6. Access to Cul-de-sacs from Adjacent Streets – To promote a pedestrian friendly
environment, a sidewalk shall be provided between cul-de-sacs and adjacent
streets.
7. Pedestrian Handrail - Pedestrian handrail of a height not less than 42 inches shall
be required when any of the following conditions are located within 5 feet of an
existing or planned public sidewalk, or as directed by the Director of Engineering:
a. A permanent or intermittent body of water;
b. Top of slope steeper than 6:1 (17%) with drop-off ending at a body of water;
c. Top of slope steeper than 3:1 (33%) with drop-off greater than 2.5 feet; OR
d. Vertical surface with drop-off greater than 2.5 feet
Pedestrian handrails are a long-term maintenance liability and may be considered
a roadside hazard and/or a general aesthetic nuisance. To minimize these
impacts, the conditions that invoke the requirement for a pedestrian handrail shall
first be reviewed for alteration to remove the hazard. If no alteration is feasible,
then a pedestrian handrail shall be constructed. Exemptions to this requirement
may be considered by the Director of Engineering when:
a. The depth of a body of water is less than 1 foot;
b. The sidewalk provides recreational access to a body of water;
c. The handrail would irreversibly spoil the natural landscape; OR
d. Alternative means of protection are approved
Pedestrian handrails located on public sidewalks shall be TxDOT Type E rails,
constructed in accordance with the PRD-06 standard (the grip rail may be
eliminated unless required by TAS/ADA requirements), or as approved by the
Director of Engineering. Any required concrete foundation shall be in addition to
the minimum sidewalk width. All rail surfaces shall be painted with industrial-grade
exterior paint, with the color approved by the Director of Engineering.
4.09. Public Rights-of-Way Visibility Requirements
A. Adequate sight distance at the intersection of a thoroughfare and a proposed
thoroughfare/driveway/alley must be ensured. This sight distance is provided through
the use of a Corner Visibility Triangle and/or a Sight Line Triangle. Corner Visibility
Triangles shall be dedicated as ROW and Sight Line Triangles shall be identified and
dedicated as Visibility, Access and Maintenance Easements (VAM’s). In addition, a
Sight Line Triangle must also be provided for the following cases:
1. Where a driveway, alley, or any thoroughfare that is controlled by a stop sign
intersects with an uncontrolled thoroughfare.
2. On any signalized intersection approach where right-turn on red operation is
permitted, a sight line triangle must be provided for the right turn driver.
B. Corner Visibility Triangle Defined:
1. The corner visibility triangle is defined at an intersection by offsetting the two ROW
lines from their point of intersection to a distance as shown on Table 4.14. These
two points are then connected with an imaginary line to form the corner visibility
triangle as shown in Figure 4.19. If there are no curbs existing, then the triangular
area shall be formed by offsetting the property lines for a distance of thirty feet
(30’) from their point of intersection.
Ordinance No. 2020-54, Page 44
ENGINEERING DESIGN STANDARDS
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TABLE 4.14: Corner Visibility Triangle Distances
Type of Thoroughfare On Type of Thoroughfare At Distance (ft)
4 or 6 Lane All Types 25
3L, Commercial 2LC 3L, 2LC 25
3L, Commercial 2LC 2LN, 2LRN 10
Residential 2LC, 2LN, 2LRN Residential 2LC, 2LN, 2LRN 10
NTTA All Types 25
FIGURE 4.19: Corner Visibility Triangle for an Intersection
2. Where alleys intersect residential 2LN or 2LRN thoroughfares, the corner visibility
triangle is measured as fifteen feet (15’) along the residential street ROW and five
feet (5’) along the alley ROW form the point of intersection. These two points are
then connected with an imaginary line to form the corner visibility triangle as shown
in Figure 4.20. The alley corner visibility triangle shall be dedicated as ROW.
FIGURE 4.20: Corner Visibility Triangle for an Alley
C. Sight Line Triangle Defined:
Ordinance No. 2020-54, Page 45
ENGINEERING DESIGN STANDARDS
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1. The sight line triangle is formed by first extending a line along the center line of the
proposed side street or driveway that begins at the tangent curb of the existing
thoroughfare and extends to its endpoint fifteen feet (15’) into the proposed side
street or driveway. For the sight line triangle to the left, construct a second
imaginary line that is parallel to and five feet (5’) out from the existing
thoroughfare’s curb that begins at the centerline of the side street and continues
to the left for a distance L to its endpoint. To complete the sight line triangle,
connect the endpoints of the first two lines as shown in Figures 4.21 and 4.22. In
the case of the sight line triangle to the right, the second imaginary line is parallel
and five feet (5’) out from the nearest edge of the conflicting traffic flow (or adjacent
median in the event of a divided thoroughfare). It begins at the centerline of the
side street and continues to the right for a distance R to its endpoint (See Figures
4.21 and 4.22).
FIGURE 4.21: Sight Line Triangle for an Undivided Thoroughfare
FIGURE 4.22: Sight Line Triangle for a Divided Thoroughfare
2. The distance to the driver’s eye for driveways or side streets that intersect a
thoroughfare is fifteen feet (15’) from the intersecting curb line as shown in Figures
4.21 and 4.22.
Ordinance No. 2020-54, Page 46
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3. In the case where the thoroughfare contains existing horizontal curvature, the
distances L and R must be measured along the horizontal curve.
4. According to the American Association of State Highway and Transportation
Officials (AASHTO), the minimum lengths of the distances L and R are equal. The
minimum sight line distances L and R vary according to the design speed and width
of the thoroughfare that will be accessed by a vehicle stopped on the side street,
as shown in Table 4.15.
TABLE 4.15: Minimum Sight Line Triangle Distances(1)
Design Speed, V
(MPH)
Minimum Sight Distance to Left and Right, L and R (ft)
2-lane
Undivided
2-lane
Divided(2) or
4-lane
Undivided
4-lane
Divided(2) or
6-lane
Undivided
6-lane
Divided(2)
25 280(3) 295 315 335
30 335 355 375 400
35 390 415 440 465
40 445 475 500 530
45 500 530 565 600
50 555 590 625 665
(1) Source AASHTO Green Book – Chapter 9. Distances based upon design speed and
width of the thoroughfare that will be accessed by a vehicle stopped on the side street.
(2) These calculations assume a median width equivalent to one travel lane. If the median is
wider than a travel lane, add 30 feet of sight distance for every 12 feet of additional
median width.
(3) L can be 150 feet with approval by the Director of Engineering or their designee.
D. Landscaping and Obstruction Requirements for corner Visibility and Site Line
Triangles:
1. No fence, wall, screen, sign, structure, foliage, hedge, tree, bush, shrub, berm,
driveway, parking space, drive aisle, or any other item, either man-made or natural
shall be erected, planted, or maintained in a position that will obstruct or interfere
with a driver’s clear line of sight within both the corner visibility and sight line
triangle (i.e., VAM’s).
2. Vision at all intersections where streets intersect at or near right angles shall be
clear at elevations between thirty inches (30”) and nine feet (9’) above the average
gutter elevation within each triangle.
E. Rights-of-Way Obstructions Outside the Site Line Triangles:
1. Fences, walls, screens, signs and other structures shall conform to the
Comprehensive Zoning and Sign Ordinances of the Town.
2. Foliage of hedges, trees and shrubs in ROW which are not governed by Prosper’s
Comprehensive Zoning Ordinance, or the above triangles shall be maintained such
that the minimum overhang above a sidewalk shall be seven feet (7’) and the
minimum over hang above a street shall be fourteen feet (14’).
3. All other areas within ROW shall be clear at elevations between thirty inches (30”)
and nine feet (9’) above the average gutter.
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4. Plants in the ROW that will grow over thirty inches (30”) (when mature) above the
adjacent street’s curb shall conform to all of the above requirements, where
applicable. All landscape plans shall show all items as required by the Parks and
Recreation Department and Planning Department, including:
a. The locations and type of such plants.
b. The prescribed corner visibility and sight line triangles.
c. Ground elevations or spot elevations as necessary, to avoid conflicts, will be
shown by contour lines within both triangles.
d. No plantings berms over thirty inches (30”) above the adjacent gutter elevation
are allowed in the median for the length of the left turn storage.
e. Single trunked trees within the triangles and in the median, shall be allowed
and spaced so as to not cause a “picket fence” effect. Because of the large
variation of ways in which trees can be planted, the spacing shall be decided
upon by the Director of Engineering or their designee and the developer at the
time of review of the landscape plans. Any other item that obstructs these lines
so as to interfere with the above requirements shall not be allowed.
F. Abatement:
1. The Director of Engineering or their designee shall have the authority to determine
whether any such fence, wall, screen, hedge, tree, bush, shrub, sign or structure,
as erected, planted or maintained, constitutes a public hazard or public nuisance
in violation of the provision of this ordinance. Upon determination, they shall cause
to be issued a written notice to the owner or lessee of the property demanding that
corrective action be taken within ten (10) days of the date the notice is mailed.
2. Following written notice, the Town of Prosper may abate the hazard or nuisance
and assess the property owner reasonable charges for labor.
3. Under conditions which pose an immediate threat to the public’s health, safety, or
general welfare, the Director of Engineering or their designee may require
immediate corrective action.
G. Exceptions – The provisions of the Roadway Design Standards shall not apply to, or
otherwise interfere with, the following:
1. Placement and maintenance of traffic control devices under governmental
authority and control.
2. Existing and future Town, State and Federal Regulations.
Ordinance No. 2020-54, Page 48
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4.10. Street Lighting
A. The following standards shall apply to all 6LD and 4LD thoroughfares:
1. Street lighting shall be placed in the medians, with spacing not to exceed three
hundred feet (300’) and no closer than one hundred fifty feet (150’) depending on
median breaks and intersections. Locations shall be determined by a photometric
plan.
2. Luminaries and poles shall be the current Town approved standard.
3. Street lighting conduit shall be two-inch (2”) Schedule 40 PVC.
4. Conduit shall be installed for irrigation to meet the landscape requirements in the
median.
B. The following standards shall apply to all 2LC commercial collectors:
1. Street lighting shall be placed in the parkway between the curb and the sidewalk,
with spacing not to exceed one hundred eighty feet (180’) and no closer than one
hundred fifty feet (150’). Locations shall be determined by a photometric plan.
2. Collector lighting shall be installed prior to final acceptance by the Town. Where
property lines bisect collectors longitudinally, each Developer is equally
responsible for their fair share of the cost of fully developed lighting. If the
Commercial Collector Street is shown on the Comprehensive Plan the Developer
can receive reimbursement through a Development Agreement.
3. Luminaries and poles shall be the current Town approved standard.
4. Street lighting conduit shall be two-inch (2”) Schedule 40 PVC.
C. The following standards shall apply to all 3L, 2LC, 2LN, and 2LRN Residential Streets:
1. Poles shall meet the standard requirements of the local electric company and
current Town standards. Upgraded options must be approved by the Director of
Engineering Services.
2. Light locations shall typically be at intersections and at mid-block if the block length
is greater than six hundred feet (600’). Cul-de-sacs, six hundred feet (600’),
measured from centerline of street to center point of cul-de-sac, shall have a light
installed at the street intersection and at the beginning of the bulb or at the top of
the bulb. Other locations may be required as deemed necessary by the Director of
Engineering Services. Lights shall not be closer than one hundred fifty feet (150’).
3. Subdivisions bounded by arterials shall have common type of luminaries.
Streetlights shall be installed prior to final acceptance by the Town.
4.11. Street Name Signs (At Non-signalized Intersections)
A. Street name signs shall be installed at all intersections of public streets, private
streets, and public ways in accordance with the Town’s Standard Details, Technical
Specifications and requirements.
B. Street name blades shall be nine inch (9”) tall extruded aluminum.
C. The street name shall be left justified, with block numbers located in the upper right-
hand corner. Abbreviated street designations shall be located in the lower right-hand
corner and right justified.
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D. The lettering of the street name shall be Clear View 2W, six inches (6”) tall and
upper/lower case. Letters of abbreviated street designations shall be three inches (3”)
tall and all uppercase (i.e., LN, PKWY, DR, CT, etc.). Block numbers shall be 3” tall.
E. A street name shall be limited to sixteen (16) characters, not including the street
designation. A street name shall either consist of one word no longer than sixteen
(16) letters or two words separated by one space where the two words have no more
than fifteen (15) letters combined.
F. Sign sheeting shall be diamond grade intensity. The background shall be green and
the legend shall be white.
G. For a street with only one cul-de-sac end, a standard W 14-2a shall be mounted under
the street name blade. In the case of a street with two cul-de-sac ends, two standard
W 14-2a signs shall be mounted under the street name blade in the appropriate
directions.
H. Owners, developers, and/or contractors should contact Development Services to
obtain block numbers. Block numbers are required on all street name blades, even if
no homes or buildings front onto the street.
4.12. Traffic Signals
A. Design Process
1. The designer shall schedule a kick-off meeting with the Town of Prosper
Engineering department to discuss signal design guidelines and requirements as
they apply to each project.
2. Obtain existing as-built plans for the intersection from the Town of Prosper or
another agency, if available.
3. Conduct a field visit to verify existing information shown on the base map prepared
by the designer.
4. Contact DIG-TESS, Town of Prosper, and adjacent public agency, as applicable,
to verify existing utility locations at the beginning of design. If needed, the designer
should also call for utility locates immediately before the award of construction
contract. Existing and proposed utilities shall be shown on the plans.
5. Schedule a field visit with the Town of Prosper Engineering Department to identify
traffic signal pole locations, controller cabinet location, power source location, and
to discuss specific issues.
6. Prepare preliminary traffic signal layout plans (60%) and submit to the Town for
review. This submittal shall include the following:
a. Traffic signal layout sheet(s) showing signal poles, vehicular and pedestrian
signal heads, barrier-free ramps and associated sidewalks, vehicle detection,
pedestrian push buttons, controller cabinet location, power source location,
electrical service, conduits, ground boxes, and all known existing and proposed
utilities. The designer should recognize that the pedestrian pushbutton
locations are often driven by the ramp locations and sidewalks.
b. Signal design tables sheet(s)
c. Pavement marking and signing sheet(s) showing all existing and proposed
pavement markings and signs.
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7. The following additional sheets may be included based on the type of project and
existing intersection condition:
a. Existing conditions layout showing the existing signal equipment to be
removed.
b. Curb ramp details
c. Geometric modifications layout showing minor intersection improvements such
as:
i. Median nose modifications to provide adequate crosswalks and/or left
turning paths.
ii. Traffic control plan sheets.
iii. Temporary signal layout plan sheets.
8. After receiving 60% submittal review comments from the Town of Prosper, the
designer shall prepare and submit 90% submittal to the Town for review. This
submittal is expected to include the following:
a. Updated traffic signal layout, signal design tables, and pavement marking and
signing, and any other additional sheets identified above.
b. All applicable standard sheets
c. General notes
d. Standard specification list (TxDOT and Town of Prosper) and special
specifications
e. Quantity summary
f. Cost estimate
g. All contract documents, if the project will be let by the Town. The Designer
should request the latest contract documents from the Town.
9. After receiving 90% submittal review comments from the Town, the designer shall
update the complete plan set and submit FINAL signed and sealed plan sets to the
Town.
B. Traffic Analysis
The Town of Prosper may request a traffic analysis for the intersection before signal
design plans are developed. The following items may be included in the traffic
analysis:
1. Turning movement counts – Collect 24-hour video turning movement counts for a
typical weekday (Tuesday, Wednesday, or Thursday school day, without rain) or
use the existing data available from the Town. The Designer should identify the
need for additional counts (i.e. weekend) based on the location of the intersection
in the Town and type of the project.
2. Synchro Analysis – Conduct AM, PM, and Mid-day peak hour capacity analysis for
the existing and future (three years) conditions.
3. Left-turn phasing – Based on the capacity analysis results and field conditions,
recommend phasing for left turns (i.e. protected only, protected/permissive, or split
phase)
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4. Storage Length – Based on the capacity analysis and queuing analysis,
recommend storage lengths for the left and right turn lanes.
5. Improvements – Based on the capacity analysis, identify short-term and long-term
improvements for each intersection.
6. Signal Timing Parameters – Provide signal timing parameters for the
existing/proposed signalized intersection as applicable. These parameters should
include pedestrian clearance times, yellow and all-red clearance times, min and
max green times for each phase, extension times, delay settings for right turn lane
detection, coordination timings (if the signal is part of a coordinated system),
overlaps, and railroad preemption timings. The designer should utilize the NCHRP
Report 731 or other industry accepted guidelines for the calculation of yellow and
all-red intervals.
C. Signal Phasing
1. If the existing controller cabinet is not being replaced, then consult the Town of
Prosper Engineering department to determine how phasing revisions (if required)
will be incorporated.
2. If the controller cabinet is being replaced or a new traffic signal is being installed,
then Phase 2 should always be Northbound Thru.
3. The Designer shall be responsible for recommending a left turn phasing based on
the intersection geometry and traffic operations inclusive of signal progression.
4. When a dedicated right turn lane is provided, a separate right turn phase (right turn
overlap) may be needed. This phase should operate in conjunction with a
compatible left turn phase.
5. When a right turn overlap is provided, U-turns from the compatible left turns may
need to be prohibited and adequate signage should be provided.
D. Traffic Signal Heads
1. All signal heads shall be LED.
2. All signal heads, including any required metal tubing, shall be made of aluminum
and brown in color.
3. All signal heads shall be fitted with brown vented aluminum back plates.
4. Louvers, if used, and the inside of the visors shall have a black finish.
5. Signal heads shall be located as specified in the latest edition of the Texas Manual
on Traffic Control Devices.
6. All signal heads shall be mounted horizontally unless otherwise directed by the
Director of Engineering Services.
7. The Town prefers to provide a signal head for each thru lane. It should be notes
that TxDOT standards typically allow up to three signal heads on standard mast
arms (up to 48 feet long) and up to four signal heads on long mast arms (LMA).
8. If a nearside signal head is required, it should be mounted on the right side of the
roadway. If roadway curvature requires mounting the nearside signal head on the
left side of the roadway, it should be mounted vertically on a signal pole.
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E. Curb Ramps, Pedestrian Signals and Push Button Assembly
1. Typically, pedestrian signal heads, Accessible Pedestrian Signals (APS),
crosswalks, and curb ramps shall be provided for all approaches to an intersection.
Specific exceptions might include situations where a pedestrian crossing would be
unsafe because of geometric conditions or traffic signal operation. Designer
should provide specific information to the Town as to why pedestrian crossing(s)
Is not provided.
2. Curb ramps should be located to provide straight crosswalks. This may require
median nose modifications. Curb ramps shall be designed according to the latest
ADA requirements.
3. All pedestrian signal heads shall be LED.
4. Accessible Pedestrian Signal System shall be Polara Navigator.
F. Signal Poles and Mast Arms
1. The Town of Prosper uses TxDOT Dallas for signal poles and mast arm
assemblies, pedestal poles, and foundations. All signal poles and pedestal poles
shall be powder coated and Brown (RAL-8008) in color.
2. If the project is an upgrade of an existing signal installation, the new poles installed
shall be similar to the existing poles that will remain in place at the intersection
(round/polygonal).
3. Standard is 30’ poles with 8’ luminaire arms – powder coated brown.
G. Conduits and Ground Boxes
1. All conduits placed under ground shall be Polyvinyl Chloride Conduit (PVC)
schedule 40. All conduits that are above ground shall be Rigid Metal Conduit
(RMC).
2. A 4” conduit ring (ground box to ground box) shall be installed around the
intersection. No ground boxes should be installed in the medians to complete a
ring.
3. A 3” conduit should be installed between the conduit ring and standard/pedestal
poles.
4. The home run (between controller cabinet and an adjacent ground box) shall have
2-4” conduits for traffic signals, 1-2” conduit for power, and one 2” conduit for future
fiber optic cable installation should be provided as part of the home run
5. A separate 2” PVC conduit shall be used for power cable between the electrical
service and the controller cabinet.
H. Electrical Conductors
Table 4.16 identifies different types of traffic signal cables and electrical conductors
used.
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Table 4.16: Signal Electrical Conductors
Location Signal Cable/ Conductors
Terminal block of mast arm signal pole to the
controller cabinet 20-Conductor #14AWG
Terminal block of pedestal pole to the controller
cabinet 10-Conductor #14 AWG
Terminal block of mast arm signal pole to each:
3-section vehicular signal head 5-Conductor #14 AWG
4-section and 5-section 7-Conductor #14 AWG
Pedestal signal head 5-Conductor #14 AWG
Terminal block of pedestal pole to pedestrian
signal head 5-Conductor #14 AWG
Electrical service meter to the controller cabinet 2 – 1 Conductor #6 XHHW
Electrical service meter to each signal pole
mounted luminaire 2 – 1 Conductor #8 XHHW
Each push button to the controller cabinet 2-Conductor #12 AWG Type C
1. All wires inside the pole (from terminal block of the signal pole to signal heads or
other devices) including traffic signal cable, electrical conductors for power and
luminaire, and communication cable shall not be paid for separately and shall be
considered subsidiary to Item 680 “Installation of Highway Traffic Signal”.
2. Power cable shall not be spliced between the electrical service and the controller
cabinet.
3. Luminaire cable shall not be spliced between the electrical service and each signal
pole mounted luminaire.
4. No. 6 Bare wire shall be used for grounding in all conduits except the run between
the power service and disconnect.
5. 2-1 Conductor #8XHHW for illumination can be daisy chained.
6. Use 2 Conductor #8XHHW for ILSN. Provide a separate photocell for ILSN/120V
circuit. ILSN conductors can be daisy chained.
7. The Town uses Type 721 uni-directional Opticom detectors and Type 764 Phase
Selectors manufactured by Global Traffic Technologies.
I. Luminaires
1. All signal pole mounted luminaires shall be Philip Lumac Road Focus Medium LED
cobra head (# RFM-108W48LED4K-T-R35-UNIV-DMG-RCD-B).
2. All signal pole mounted luminaires at an intersection shall be controlled with a
central photocell which will be installed inside an enclosure mounted on the service
pedestal.
3. The luminaire arm mounted on the traffic signal pole shall be 8’ long.
J. Electrical Service
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1. Typically, the Town of Prosper uses pedestal type electrical service for traffic signal
installations requiring new power using the following code:
a. Type D (120/240)070(NS)AL(E)PS(U)
2. The designer shall verify the location of a power source with the appropriate utility
company and discuss the type of service that will be installed at each intersection
with the Town of Prosper Engineering Department.
K. Detection Systems
The Town of Prosper typically uses Radar Vehicle Detection System that meet the latest
TxDOT special specifications for Radar Vehicle Detection System for Signalized
Intersection Control.
The designer shall discuss the type of detection system and detection system layout to be
used at each intersection with the Town of Prosper Engineering Department.
L. Traffic Signal Controller and Cabinet Assembly
1. The Town of Prosper uses Econoline Cobalt controllers. The designer should request
the latest controller model number from the Town.
2. The Town of Prosper uses NEMA TS2 (TxDOT Specification traffic signal controller
cabinets with shelf or externally mounted Battery Back-Up-System (BBU System). For
all on-system (TxDOT roadways) intersections, BBU shall be externally mounted.
However, the designer should verify with the Town and TxDOT staff. Traffic signal
controller cabinet and BBU (if externally mounted) shall be powder coated brown
(RAL-8008).
3. Traffic signal controller cabinet shall be installed according to the TxDOT standard
specification TS-CF.
4. A concrete apron shall be installed around the controller cabinet.
M. Illuminated Street Name Signs (ILSN)
1. Typically, the Town of Prosper uses cantilever ILSN arm (TxDOT specifications) above
the mast arm, mounted at 24 feet height. Mast arm mounted ILSN are allowed only if
19 feet high signal pole is used.
2. The Town uses Clean Profile series ILSN manufactured by Southern Manufacturing.
The contractor shall be responsible for furnishing and installing the ILSN and all
mounting hardware according to the Town’s specifications (attached).
3. On specific projects, the Town may require the contractor to furnish and install
standard street name sign blades. In this case, the Town will provide the Town of
Prosper logo to be installed on the street name sign furnished by the contractor.
N. Communication System
The Designer shall provide one-2” conduit for future fiber optic cable installation from
signal controller cabinet to the adjacent ground box (home run).
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O. Red Light Confirmation Lamp
The Designer should request that latest specifications for Red Light Confirmation Lamp
from the Town’s Engineering Department.
P. Traffic Control During Construction/USE of Temporary Signals
1. The Designer shall discuss their approach for traffic control during signal construction
with the Town of Prosper Engineering Department.
2. If it is determined that traffic control plans and/or temporary signal plans are required
on a project, the designer shall be responsible for preparing such plans.
3. Traffic control requirements during construction will vary depending on the type of
project. For example, a new traffic signal installation may not require traffic control
plans, while signal modifications as part of a roadway construction project may require
traffic control plans and/or temporary (span wire) signal installation.
4. If required, span wire signal design plans shall be prepared according to TxDOT Dallas
standard sheet “Construction Details for Span Wire Mounted Signals”.
5. Plans shall clearly indicate how transition from the existing traffic signal equipment to
the new signal equipment will be accomplished for traffic signal modifications.
Installation of temporary signals may be required.
4.13. Traffic Impact Analysis Mitigation
A. Purpose – The purpose of a traffic Impact Analysis (TIA) is to assess the effects of
specific development activity on the existing and planned thoroughfare system.
Development activity may include but is not limited to rezoning, preliminary site plans,
site plans, preliminary plats, driveway permits, certificates of occupancy, and
Thoroughfare Plan amendments.
B. Pre-application meeting – Prior to the commencement of a TIA, an initial or pre-
application meeting with Town staff is required to establish a base of communication
between the Town and the applicant. This meeting will define the requirements and
scope relative to conducting a TIA and ensure that any questions by the applicant are
addressed.
C. Applicability of TIA Requirements:
1. Zoning – These TIA requirements shall apply to all zoning requests for land uses
which will generate 2,500 or more vehicle trips per day or contain a density of 0.75
Floor Area Ratio (FAR) or greater. Applicable requests include zoning requests
and Thoroughfare Plan amendments, if no previous traffic assessment was
performed. Special circumstances, including but not limited to development with
no case history, which to not meet the daily trip generation threshold, may also
require a TIA. Such circumstances, as determined by the Director of Engineering
Services may include, but are not limited to, impacts to residential neighborhoods
from non-residential development, inadequate site accessibility, the
implementation of the surrounding Thoroughfare Plan is not anticipated during the
estimated time period of the proposed development, the proposed land use differs
Ordinance No. 2020-54, Page 56
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significantly from that contemplated in the Comprehensive Plan, or the internal
street or access is not anticipated to accommodate the expected traffic generation.
2. Development – These TIA requirements shall apply to all development requests
for land uses, except single-family residential development, which will generate
over 100 total trips during the AM or PM peak hour. Applicable development
requests include concept plans, preliminary site plans, site plans and preliminary
plats. Special cases, in which site generated peak hour trip activity is different from
that of the adjacent street (weekdays 7:00-9:00 a.m. and 4:00-6:00 p.m.), may
require and additional separate analysis as determined by the Director of
Engineering Services. such circumstances may include, but are not limited to,
commercial/retail, entertainment or institutional activity. The Director of
Engineering Services may waive the TIA for a development request if a TIA was
performed previously with the Zoning request and conditions listed in the report
are still current.
3. Single-Family Residential Exception – A TIA for single-family residential
development will not be required if the development contains fewer than six
dwelling units unless special circumstances exist, as determined by the Director of
Engineering Services. These special circumstances may include, but are not
limited to, impacts to other residential development from cut-through traffic,
inadequate site accessibility, the implementation of the surrounding Thoroughfare
Plan is not anticipated during the estimated time period of the proposed
development, the internal street or access system is not anticipated to
accommodate the expected traffic generation, or the development is outside the
urban core of the community.
4. Daycares and Schools – All development requests and/or specific use permit
requests for a daycare, Montessori school, private school, charter school, or public
school shall include, at a minimum, a traffic circulation study. This study shall
include the estimated maximum peak hour trip generation of the facility, the
planned circulation of inbound and outbound traffic during drop-off and pick-up
operations, and the estimated length of the queue of cars waiting to pick up
students. The design of the site and the circulation plan shall ensure that school
traffic does not back up onto any public street. The traffic circulation study shall
include a statement that the owner and/or operator of the daycare or school agrees
to operate the facility in accordance with the approved circulation plan. The
circulation plan must be approved by the Director of Engineering Services before
the development request or the specific use permit can be approved.
5. Determination of Applicability – The need for a TIA shall be determined by the
Director of Engineering Services based upon the results and recommendation from
a pre-application meeting. It shall be the responsibility of the applicant to
demonstrate that a TIA should not be required. If a TIA is required, the level of
effort for a TIA submission shall be determined based on the criteria set forth in
Table 4.17. Depending upon the specific site characteristics of the proposed
development, one or more of the following elements may also be required as part
of the TIA: an accident analysis, sight distance survey, traffic simulation, traffic
signal warrant analysis, queuing analysis, turn lane analysis, and/or traffic
circulation plan.
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TABLE 4.17: Criteria for Determining TIA Study Requirements
Analysis
Category
Site Trips
Generated at Full
Build-Out
TIA Analysis
Periods(1)
Minimum Study Area(3)
I >50 peak hour
driveway trips; or
100-500 total peak
hour trips
1. Existing year
2. Opening year(2)
3. Five years after
opening
1. All site access drives
2. All signalized
intersections and/or
major un-signalized
intersections within
0.5 mile to 1 mile of
site boundary
II >500 total peak
hour trips
1. Existing year
2. Opening year of
each phase
3. Five years after
initial opening
4. Ten years after final
opening with full
build-out
1. All site access drives
2. All signalized
intersections and/or
major un-signalized
intersections within
1.5 of site boundary
(1) Analysis periods shall include build and no-build scenarios. Assume full occupancy when
each phase opens.
(2) Assume full build-out.
(3) For certain projects, the Town may require an enlarged study area. Land uses within the
study area should include recently approved or pending development adjacent to the
site.
D. Requirements for TIA Updates – A TIA shall be updated when time or circumstances
of the original study fall within the parameters presented in Table 4.18. The applicant
is responsible for preparation and submittal of appropriate documentation in order for
Town staff to process the zoning or development application. A TIA for site
development requests must be updated if two years have passed since the original
submittal, or if existing or assumed conditions have changed within the defined study
area. The Director of Engineering Services shall make the final determination as to the
extent of a TIA update.
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TABLE 4.18: Criteria for Determining TIA Update Requirements
Original TIA
Report was
based on:
Changes to the Originally Proposed Development
Access Changed(1) or Trip
Generation Increased by more
than 10%
Access Not Changed and Trip
Generation Increased by less than
10%
Zoning; or
Preliminary Site
Plane or Site
Plan that is less
than 2 years old
Letter Amendment Required:
Identify and report only analysis
conditions that have changed.
Letter Documenting Change (No
analysis is required)
Preliminary Site
Plan or Site Plan
that is more than
2 years old
Prepare New Study. Must meet
all current TIA requirements
Prepare New Study. Must meet all
current TIA requirements
(1) Changed access includes proposed new access or refinement of general access
locations not specifically addressed in original proposed development.
E. Responsibility of TIA Preparation and Review:
1. A TIA shall be prepared in accordance with all of the guidelines in this section and
submitted in accordance with the Development Review Schedule set by the Town.
The responsibility for TIA preparation shall rest with the applicant and must be
performed by a Professional Engineer (P.E.) licensed in the State of Texas with
experience in traffic and transportation engineering. The final TIA report must be
signed and sealed by the P.E. responsible for the analysis to be considered for
review by the Town. Application and review fees are due at the time of each
submittal. Town staff shall serve primarily in a review and advisory capacity and
will only provide data to the applicant when available.
2. It shall be the responsibility of the applicant to submit four (4) draft TIA reports and
executive summaries with the zoning and/or development request submission.
The proper number of reports, the timing for submission, and the review of these
reports shall be based on standard Town development review procedures.
Incomplete TIAs or failure to submit a TIA with the submission shall delay
consideration of zoning and development requests. Should it be determined during
the review of any zoning and/or development plans that a TIA is required,
consideration shall be deferred until the applicant submits a completed TIA and
the Town has reviewed the assessment.
3. The Town shall review the TIA and provide comments to the applicant. It shall be
the responsibility of the applicant to submit four (4) finalized TIA reports and
executive summaries once all review comments have been addressed.
F. TIA Standards:
1. Design Level of Service – The minimum acceptable level of service (LOS) within
the Town shall be defined as LOS “D” in the peak hour for all critical movements
and links. All development impacts on both thoroughfare and intersection
operations must be measured against this standard.
2. Trip Generation Resources – The Town’s standard for trip generation rates for
various land use categories shall be those found in the latest edition of Trip
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Generation published by the Institute of Transportation Engineers (ITE) or other
published or recognized sources applicable to the region. Alternate trip generation
rates may be accepted on a case-by-case basis if the applicant can provide current
supporting data substantiating that their development significantly differs from the
ITE rates. The Director of Engineering Services must approve alternative trip
generation rates in writing in advance of the TIA submission.
3. Trip Reductions – Trip reductions for passer-by trips and mixed-use developments
will be permitted, subject to analytical support provided by the applicant and
approval by the Director of Engineering Services on a case-by-case basis.
Assumptions relative to automobile occupancy, transit mode share, or percentage
of daily traffic to occur in the peak hour must be documented and will be considered
subject to analytical support provided by the applicant.
4. Study Horizon Years – The TIA must evaluate the impact of the proposed
development on both existing traffic conditions and future traffic conditions for the
horizon year(s) as specified in Table 4.18. however, applications for densities of
0.75 Floor Area Ratio (FAR) or greater within the Dallas North Tollway, US 380, or
Preston Road corridors (throughout the Town Limits) shall require that the horizon
year land use assumptions be updated to reflect full development based on all
proposed zoning. These applications should also assume full development of the
Master Thoroughfare Plan or pending amendments.
G. TIA Methodology:
1. Site Location/Study Area – A brief description of the size, general features, and
location of the site, including a map of the site in relation to the study area and
surrounding vicinity.
2. Existing Zoning – A description of the existing zoning for the site and adjacent
property, including land area by zoning classification and density by FAR, square
footage, number of hotel rooms, and dwelling units (as appropriate).
3. Existing Development – A description of any existing development on the site and
adjacent to the site and how it would be affected by the development proposal.
4. Proposed Zoning/Site Development – A description of the proposed
zoning/development for the site, including land area by zoning classification and
density by FAR, square footage, number of hotel rooms, and dwelling units (as
appropriate); identify other adjacent land uses that have similar peaking
characteristics as the proposed land use; identify recently approved or pending
land uses within the area.
5. Thoroughfare System – A description and map of existing planned or proposed
thoroughfares and traffic signals for horizon years(s) within the study area.
6. Existing Traffic Volumes – Recent traffic counts for existing thoroughfares and
major intersections within the study area.
7. Projected Traffic Volumes – Background traffic projections for the planned
thoroughfare system within the study area for the horizon years.
8. Density of Development – A table displaying the amount of development assumed
for existing zoning and/or the proposed development (using gross floor area,
dwelling units, occupied beds, etc., as required by the trip generation
methodology).
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9. Existing Site Trip Generation – A table displaying trip generation rates and total
trips generated by land use category for the AM and PM peak hours and on a daily
basis, assuming full development and occupancy based on existing zoning (if
applicable), and including all appropriate trip reductions (as approved by the
Director of Engineering Services).
10. Proposed Site Trip Generation – A table displaying trip generation rates and total
trips generated by land use category for the AM and PM peak hours and on a daily
basis, assuming full development and occupancy for the proposed development,
and including all appropriate trip reductions (as approved by the Director of
Engineering Services).
11. Net Change in Trip Generation (for rezoning cases) – Proposed trip generation
minus existing trip generation (if applicable); the net increase in trips to be added
to base volumes for the design year.
12. Trip Distribution and Traffic Assignment – Tables and figures of trips generated by
the proposed development (or net change in trips, if applicable) added to the
existing and projected volumes, as appropriate, with distribution and assignment
assumptions, unless computer modeling has been performed.
13. Level of Service Evaluations – Capacity analyses for weekday AM or PM peak
hours of the roadway and peak hour of the site, if different from the roadway, for
both existing conditions and horizon year projections for intersections,
thoroughfare links, median openings and turn lanes associated with the site, as
applicable.
14. Traffic Signal Evaluations – The need for new traffic signals based on warrants
and their impact on the performance of the transportation system.
15. Evaluation of Proposed/Necessary Mitigation – Capacity analyses for weekday AM
and PM peak hours of the roadway and peak hour of the site, if different from the
roadway, for intersections, thoroughfare links, median openings and turn lanes
associated with the site under proposed/necessary traffic mitigation measures.
16. Conclusions – Identification of all thoroughfares, driveways, intersections, and
individual movements that exceed LOS D or degrade by one or more LOS, the
percentage of roadway volume change produced by the proposed development,
and any operational problems likely to occur.
17. Recommendations – Proposed impact mitigation measures consistent with
Subsection I below.
18. Other information required for proper review – As requested by the Director of the
Engineering Services.
H. TIA Report Format:
1. The TIA report must be prepared on 8.5” x 11” sheets of paper. However, it may
contain figures on larger sheets, provided they are folded to this size. All text and
map products shall be computer-based and provided in both published format and
computer file format (PDF). In addition, all electronic files used as part of the traffic
analysis (i.e., Synchro, HCS, Passer II/III, CORSIM, VISSIM, etc.) shall be
provided.
2. The sections of the TIA report should be categorized according to the outline
shown below:
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Executive Summary
A. Introduction
1. Purpose
2. Methodology
B. Existing and Proposed Land Use
1. Site Location/Study Area
2. Existing Zoning
3. Existing Development
4. Proposed Zoning (if applicable)
C. Existing and Proposed Transportation System
1. Thoroughfare System
2. Existing Traffic Volumes
3. Projected Traffic Volumes
D. Site Traffic Characteristics
1. Existing Site Trip Generation (if applicable)
2. Proposed Site Trip Generation
3. Net Change in Trip Generation (if applicable)
4. Trip Distribution and Traffic Assignment
E. Traffic Analysis
1. Level of Service Evaluations
2. Traffic Signal Evaluations
F. Mitigation
G. Conclusions
H. Recommendations
Appendices
I. Traffic Impact Mitigation:
1. Mitigation of traffic impacts shall be required if the proposed development would
cause a facility or traffic movement to exceed LOS D, or where it already exceeds
LOS D and the development would contribute five percent (5%) or more of the total
traffic during any projected horizon year. If mitigation is required, the applicant
must only mitigate the impact of the proposed development, and would not be
responsible for alleviating any deficiencies in the thoroughfare system that may
occur without the proposed development.
2. Acceptable mitigation measures shall include:
a. Staging of development in order to relate site development to the construction
of the required thoroughfare system;
b. Staging of development so that the site contributes less than five percent (5%)
of the total traffic to the affected facility or traffic movement during the projected
horizon year;
c. Off-site improvements, including the provision of right-of-way and/or the
participation in funding for needed thoroughfare and intersection improvement
projects (including, but not limited to, through lanes, turn lanes or traffic
signals); and
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d. On-site improvements, including access controls and site circulation
adjustments.
3. Mitigation is not required if it can be shown that the traffic impacts of the project
are fully mitigated ten (10) years after the final opening with any improvements that
are already programmed to be implemented within five (5) years of the initial
opening.
J. Administration of the TIA – Based on the results of the TIA and actions recommended
by the Director of Engineering Services, the Planning & Zoning Commission and/or
the Town Council, as appropriate, shall take one or more of the following actions:
1. Approve the zoning or development request, if the project has been determined to
have no significant impact or where the impacts can be adequately mitigated;
2. Approve the development request, subject to a phasing plan;
3. Recommend study of the Town Thoroughfare Plan to determine amendments
required to increase capacity;
4. Recommend amendment of the Capital Improvement Plan (CIP) to expedite
construction of needed improvements; or
5. Deny the zoning or development request, where the impacts cannot be adequately
mitigated.
K. Cost of TIA Review by Town – The cost for review of TIA submittals shall be based on
the parameters set forth in the Town’s Development Fee Schedule and paid in full at
time of submission.
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4.14. Post-Development Traffic Calming Guidelines
A. Introduction:
1. Traffic Calming, a concept that dates back to the 1960’s and 70s, has been
implemented more extensively throughout the United States during the 1990s. The
primary purpose of traffic calming is to decrease speeds and reduce cut-through
traffic volumes. The Institute of Transportation Engineers (ITE) defines traffic
calming as follows:
“Traffic Calming is the combination of mainly physical measures that
reduce the negative effects of motor vehicle use, alter driver behavior and
improve conditions for non-motorized street users.”
2. Urban sprawl and traffic congestion continue to increase in the United States. As
a result, speeds and cut-through volumes on local streets and collectors will
continue to increase unless traffic calming measures are put in place or new local
and collector thoroughfares are designed with traffic calming in mind.
3. The Roadway Design Standards and Subdivision Ordinances are intended to
provide design and access requirements that are proactive in addressing traffic
calming issues in residential areas. In instances where problems exist that can be
addressed by traffic calming, a specific process will be used to identify the
problem and potential solutions.
4. Traffic control devices such as STOP Signs and speed limit signs are regulatory
measures that require enforcement. Traffic calming measures, however, are
intended to be self-enforcing.
B. Traffic Calming Process - The traffic calming process contains steps that include the
three E’s commonly found in traffic calming programs. These E’s are Education,
Enforcement and Engineering. In many instances, applying the Education and
Enforcement steps will solve the problem without implementing a costlier engineering
solution. The traffic calming process will use the following steps:
1. Neighborhood must identify a problem and bring it to the Town’s attention with a
petition signed by seventy-five percent (75%) of the property owners along the
street.
2. The Town will conduct a study, funded at the property owners’ expense, to
determine the extent of the reported problem.
3. The Town will examine the results of the study.
4. If the study indicates that a problem exists, the Town will identify if there are
additional stakeholders in solving the problem. These additional stakeholders will
typically include emergency services and the school district.
5. If a speeding problem exists, the Town will then:
a. Identify possible causes.
b. Work with the neighborhood to raise awareness to the problem (Education).
c. Increase the enforcement level after the education process (Enforcement).
d. Conduct another study to determine if Education and Enforcement have solved
the problem.
e. If a speeding problem still exists, the Town will then:
i. Determine the best traffic calming measure to apply (Engineering).
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ii. Determine whether the solution should be a temporary installation or
permanent installation.
iii. Conduct an after study to see if the measure has had the desired effect.
6. If a cut-through problem exists, the Town will then:
a. Identify possible causes.
b. Examine the area roadway network to determine the best solution.
c. Work with surrounding neighborhoods to implement a solution. This step is
necessary because traffic calming measures that address this problem may
move the cut-through traffic to another neighborhood street.
d. Conduct an after study to determine if the solution was effective.
C. Role of Emergency Services and School District – The traffic calming process must
involve Fire and Rescue, Police and the School District (bussing). It is recommended
that these agencies play an advisory role. Some measures may delay emergency
response time. It is imperative that each neighborhood realizes that this is a trade-off
when implementing traffic calming measures. All traffic calming measures must be
designed to accommodate emergency vehicles and school buses.
D. Traffic Calming Measures – Below is a list of traffic calming solutions for speed related
problems and cut-through traffic problems. The solutions are listed in no particular
order.
1. Potential Solutions for Speed Related Problems:
a. Chokers – midblock
b. Neckdowns – at intersection
c. Neighborhood speed watch program
d. Realigned intersections
e. Medians
f. Traffic circles/roundabouts
g. Lateral shifts
h. Textured pavements
Note: STOP signs are not intended for speed control. Studies have shown that
installation of STOP signs to control speed actually increase the speeds
measured at midblock locations between STOP signs.
2. Potential Solutions for Cut-Through Traffic Related Problems:
a. Diverters
b. Median Barrier
c. Turn restrictions
d. Street closures
4.15. Internal Site Circulation Requirements
Site Circulation within private development must meet all Town standards as set forth in
the Town of Prosper Zoning Ordinance and Prosper’s Fire Code as well as all applicable
standards listed in previous sections of this manual. Site Circulation should also consider
safe design for all drivers, pedestrians and other users.
A. Proper internal site circulation includes, but is not limited to, proper channelization and
alignment of intersections, turning radii, fire truck access and maneuverability, sight
distance, traffic control devices, traffic queue management, loading dock access,
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delivery truck activity, loading zones, trash pickup location and procedures, parking lot
circulation, crosswalk alignment, crosswalk location, ADA access routes, etc.
B. Fire Lanes, also known as Fire Apparatus Access Roads, must meet the requirements
and provisions listed in the Town of Prosper Code of Ordinances: Fire Code. Basic
requirements include:
1. All fire lanes must be a minimum of twenty-four feet (24’) wide with all radii a
minimum of thirty feet (30’), or thirty feet (30’) wide with minimum radii of twenty
feet (20’) if intersecting with another thirty-foot (30’) wide fire lane. If a thirty-foot
(30’) section intersects a twenty-four-foot (24’) section, the radii must be a
minimum of thirty feet (30’). A thirty-foot (30’) wide fire lane can taper down to
twenty-four (24’) with a 10:1 transition (ten longitudinal feet to every one foot of
width).
2. Fire lanes required for fire protection for structures over 30 feet in height shall
require fire lane width to be increased to twenty-six feet (26’) wide. Radii as
previously described for twenty-four (24) foot wide fire lanes apply.
3. Dead-end fire lanes over 100 ft are prohibited without an approved turnaround.
4. Pavement and subgrade requirements can be found in the Town’s Paving and
Subgrade Design manual.
5. The curvature and/or alignment of a fire lane within a site shall not create difficult
geometry for fire trucks to navigate, as determined by the Fire Department. Some
specific requirements include
a. When a fire lane contains a reverse curve (or S-curve) in its alignment, there
must be a tangent at least twenty feet (20’) long between the reverse curve
and the next curve in the alignment or the next curb return of a fire lane
intersection.
6. Fire Lane design should be designed in manner to discourage excessive speeds,
"cut-thru" traffic or other hazardous conditions. If excessive speeds or other
hazardous conditions have been determined, speeds cushions meeting Town
standards may be approved by the Town of Prosper Fire Marshal.
a. Speed Cushions shall not be used for initial design, as original design should
be done in manner to discourage unsafe conditions.
C. Internal development parking and drive aisles must meet minimum requirements as
depicted in the Town of Prosper’s Zoning Ordinance. Basic requirements include:
1. Parking stalls shall be a minimum of 9 ft wide x 20 ft in length. Stalls may be
shortened to 18 ft if a two-foot car overhang exclusive of landscape setbacks is
provided.
2. Drive aisles with 90 head in parking must be a minimum of 24 ft wide.
3. Drive aisles with angled parking must meet minimum widths as depicted in Chapter
5, Section 2 Appendices in the Town’s Zoning Ordinance.
4. Drive aisles designated as Fire Lanes shall meet all minimum Fire Lane Standards.
D. Drive-through Restaurants and Businesses
1. Drive-through restaurants and businesses shall be designed so that traffic queued
up to use the business shall not block a fire lane, block required parking spaces,
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interfere with traffic circulation for other businesses, block a driveway entrance to
the shopping center, nor back up into a public street.
2. Drive-through restaurants and businesses shall be designed so that the drive-
through lane never ends with its traffic traveling parallel to traffic traveling in the
opposite direction.
3. Escape Lanes shall be designed as outlined in the Town’s Zoning Ordinance
Section 4.4.9.B of the Town’s Zoning Ordinance for any use containing a drive-
through facility.
4. Queuing - Staking spaces provide the ability for vehicles to queue on site prior to
receiving a service. Stacking spaces shall be provided as required in Section
4.4.9.B of the Town’s Zoning Ordinance.
E. Daycares and Schools – sufficient stacking shall be provided for child drop off and
pick-ups so that queuing does not back up into fire lanes or public right-of-way,
especially during peak hours. A site circulation study may be required.
F. Car Washes – sufficient stacking shall be provided so that queuing does not back up
into fire lanes or public right-of-way, especially during peak hours. A site circulation
study may be required.
G. Dumpster Geometry – dumpster widths, location, backing and maneuvering shall be
in accordance with the current Town’s waster provider. Guidelines and standards are
available upon request.
H. Structured Parking Garages:
1. Parking garages containing five hundred (500) or more parking spaces shall have
at least two driveway access points, each with a minimum of two lanes. If a parking
garage is allowed to have only one driveway access point, that driveway shall have
a minimum of one (1) inbound lane and two (2) outbound lane.
2. Parking garages shall have at least one pedestrian entrance which does not
require pedestrians to walk in a driveway access point to enter the garage. This
pedestrian entrance shall be served by a sidewalk connection that complies with
the most current federal, state, and local ADA requirements. Additional pedestrian
entrances may be required as deemed necessary by the Director of Engineering
Services.
3. Where vehicles exit a parking garage, the fire lane shall be located at least fifteen
feet (15’) away from the exterior wall or column of the parking garage exit so
adequate sight distance is provided for exiting vehicles.
4. The size of parking spaces within a parking garage is dictated by the Zoning
Ordinance. If the parking spaces are eighteen feet (18’) deep, no column or barrier
cable is allowed to encroach into a parking space beyond an area measuring
fourteen inches (14”) by fourteen inches (14”) in one front corner of that parking
space. If the parking spaces are deeper than eighteen feet (18’), the encroachment
area shall be no wider than fourteen inches (14”) and no deeper than twenty-six
inches (26”) in one front corner of that parking space. If barrier cables are installed
across the entire width of a parking space, the required parking space depth must
be measured from the face of the barrier cable(s).
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