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Section 2: Urban Streets

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Overview

The term “Urban Street” as used in this chapter refers to roadways in developed areas that provide access to abutting property as well as movement of vehicular traffic. Access for these facilities is controlled only through driveway locations and medians.

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Level of Service

Urban streets and their auxiliary facilities should be designed for level of service B as defined in the Highway Capacity Manual. Heavily developed urban areas may necessitate the use of level of service D. The class of urban facility should be carefully selected to provide the appropriate level of service. For more information regarding level of service as it relates to facility design, see Service Flow Rate under subhead Traffic Volume in Chapter 2.

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Basic Design Features

This subsection includes information on the following basic design features for urban streets:

Table 3-1 shows tabulated basic geometric design criteria for urban arterial, collector, and local streets. The basic design criteria shown in this table reflects minmum and desirable values applicable to new location, reconstruction or major improvement projects (such as widening to provide additional lanes).

Anchor: #CIHBBACGTable 3-1: Geometric Design Criteria for Urban Streets

(US Customary)

Item

Functional Class

Desirable

Minimum

Design Speed (mph)

All

Up to 60

30

Minimum Horiz. Radius

All

See Tables 2-3 and 2-4, Figure 2-2

Maximum Gradient (%)

All

See Table 2-9

Stopping Sight Distance

All

See Table 2-1

Width of Travel Lanes (ft)

Arterial

Collector

Local

12

12

11-12

111

102

102,3

Curb Parking Lane Width (ft)

Arterial

Collector

Local

12

10

9

104

75

75

Shoulder Width6 (ft), Uncurbed Urban Streets

Arterial

Collector

Local

10

8

--

4

3

2

Width of Speed Change Lanes (ft)

Arterial and Collector

Local

11-12

10-12

10

9

Offset to Face of Curb (ft)

All

2

1

Median Width

All

See Medians

Border Width (ft)

Arterial

Collector

20

20

15

15

Right-of-Way Width

All

Variable 7

Clear Sidewalk Width (ft)10

All

6-88

5

On-Street Bicycle Lane Width

All

See Chapter 6, Bicycle Facilities

Superelevation

All

See Chapter 2, Superelevation

Horizontal Clearance Width

All

See Table 2-11

Vertical Clearance for New Structures (ft)

All

16.5

16.59

Turning Radii

-

See Chapter 7, Minimum Designs for Truck and Bus Turns

1In highly restricted locations or locations with few trucks and speeds less than or equal to 40 mph, 10 ft permissible.

2 In industrial areas 12 ft usual, and 11 ft minimum for restricted R.O.W. conditions. In non-industrial areas, 10 ft minimum.

3 In residential areas, 9 ft minimum.

4 Where there is no demand for use as a future through lane, 8 ft minimum.

5 In commercial and industrial areas, 8 ft minimum.

6 Where only minimum width is provided, it should be fully surfaced. Where desirable width is provided, partial (not less than minimum width) surfacing or full width surfacing may be provided at the option of the designer.

7 Right-of-way width is a function of roadway elements as well as local conditions.

8 Applicable for commercial areas, school routes, or other areas with concentrated pedestrian traffic.

9 Exceptional cases near as practical to 16.5 ft but never less than 14.5 ft. Existing structures that provide at least 14 ft may be retained.

10 Cross slopes, ramps, and sidewalks shall be in compliance with the Americans with Disabilities Act Accessibility Guidelines and the Texas Accessibility Standards. See Chapter 2, Curb and Curb and Gutters and Sidewalks and Pedestrian Elements.



Anchor: #i1062895Table 3-1: Geometric Design Criteria for Urban Streets

(Metric)

Item

Functional Class

Desirable

Minimum

Design Speed (km/h)

All

Up to 100

50

Minimum Horiz. Radius

All

See Tables 2-3 and 2-4, Figure 2-2

Maximum Gradient (%)

All

See Table 2-9

Stopping Sight Distance

All

See Table 2-1

Width of Travel Lanes (m)

Arterial

Collector

Local

3.6

3.6

3.3-3.6

3.31

3.02

3.02,3

Curb Parking Lane Width (m)

Arterial

Collector

Local

3.6

3.0

2.7

3.04

2.15

2.15

Shoulder Width 6 (m), Uncurbed Urban Streets

Arterial

Collector

Local

3.0

2.4

--

1.2

0.9

0.6

Width of Speed Change Lanes (m)

Arterial and Collector

Local

3.3-3.6

3.0-3.6

3.0

2.7

Offset to Face of Curb (m)

All

0.6

0.3

Median Width

All

See Medians

Border Width (m)

Arterial

Collector

6.0

6.0

4.5

4.5

Right-of-Way Width

All

Variable 7

Clear Sidewalk Width (m)10

All

1.8-2.48

1.5

On-Street Bicycle Lane Width

All

See Chapter 6, Bicycle Facilities

Superelevation

All

See Chapter 2 Superelevation

Horizontal Clearance Width

All

See Table 2-11

Vertical Clearance for New Structures (m)

All

5.0

5.09

Turning Radii

-

See Chapter 7, Minimum Designs for Truck and Bus Turns

1 In highly restricted locations or locations with few trucks and speeds less than or equal to 60 km/h 3.0 m permissible.

2 In industrial areas 3.6 m usual, and 3.3 m minimum for restricted R.O.W. conditions. In non-industrial areas, 3.0 m minimum.

3 In residential areas, 2.7 m minimum.

4 Where there is no demand for use as a future through lane, 2.4 m minimum.

5 In commercial and industrial areas, 2.4 m minimum.

6 Where only minimum width is provided, it should be fully surfaced. Where desirable width is provided, partial (not less than minimum width) surfacing or full width surfacing may be provided at the option of the designer.

7 Right-of-way width is a function of roadway elements as well as local conditions.

8 Applicable for commercial areas, school routes, or other areas with concentrated pedestrian traffic.

9 Exceptional cases near as practical to 5.0 m but never less than 4.4 m. Existing structures that provide at least 4.3 m may be retained.

10 Cross slopes, ramps, and sidewalks shall be in compliance with the Americans with Disabilities Act Accessibility Guidelines and the Texas Accessibility Standards. See Chapter 2, Curb and Curb and Gutters and Sidewalks and Pedestrian Elements.



For minor rehabilitation projects where no additional lanes are proposed, existing curbed cross sections should be compared with the design criteria in Table 3-1 to determine the practicality and economic feasibility of minor widening to meet the prescribed standards. Where only minimal widening is required to conform with a standard design, it is often cost effective to retain the existing street section, thereby sparing the cost of removing and replacing concrete curb and gutter and curb inlets. For these type projects, Resurfacing, Restoration, and Rehabilitation (3R) guidelines are usually applicable, see Chapter 4.

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Medians

Medians are desirable for urban streets with four or more traffic lanes. The primary functions of medians are to provide the following:

  • storage space for left-turning vehicles
  • separation of opposing traffic streams
  • access control to/from minor access drives and intersection.

    Medians used on urban streets include the following types:

  • raised
  • flush
  • two-way left-turn lanes.

    Raised Medi