Street Network Design

The overall pattern of streets and their specific designs should promote walkability and access between areas of living, work, commercial activity, and recreation. This implies the utilization of a roadway pattern that provides a reasonably direct route as well as amenities that provide safe choices for vehicles, bicyclists and pedestrians.

Grid Connectivity

A well-connected grid pattern supports walkability by providing direct routes from several origin points. Street patterns should be designed to maximize network connections and avoid “dead end” segments that result in circuitous paths.

Link-node ratio is a measurement frequently used to quantify the connectivity of a street grid. It measures the ratio of links (street segments) to nodes (intersections or dead ends). Areas with bus transit service should strive to enhance connectivity by providing as many links as possible between network nodes, and therefore, a higher link-node ratio.

Block Size

Access to transit is often impacted by the size of blocks. Large blocks limit opportunities for direct walking routes and create large segments of roadway that can be difficult to cross for pedestrians. The Chicago region’s traditional block dimensions are approximately 600’ long and 300’ wide, though blocks are often 300’ by 300’ in downtown areas. Though standard block size varies by community, block sizes in areas served by transit should not exceed 600’ in length, and should be between 300’ and 350’ in downtown areas.

Right-of-way Width

The size of the right-of-way has direct impacts on transit access in terms of what types of vehicles and infrastructure can be accommodated, what kind of service may operate, and to what extent it inhibits pedestrian access to the service and facilities. The widths of rights-of-way vary greatly throughout the region based on the classification and jurisdiction of a specific roadway, as well as the context within which it operates. Currently, rights-of-way for major suburban arterials tend to be between 100-150’ and typically have expansive parkway strips along each curb, while more traditional commercial streets are approximately 75-90’. Existing local streets may have rights-of-way from 60-75’. Transit-supportive rights-of way should provide the space necessary for vehicular, bicycle and pedestrian operations, yet minimize unnecessary elements that create additional space and barriers between local activities and transit services.

The following sections describe transit supportive rights-of-way for various roadway configurations.

60’ Right-of-way

Streets with a 60’-75’ right-of-way are typically local streets that host residential or community-based commercial activities. Generally, these streets should aim to provide local multi-modal access to goods and services. Transit, bicycle and pedestrian circulation should be a high priority.

Multi-modal access

The cross-section should balance local priorities related to dedicated bicycle facilities and adequate pedestrian areas

Bike lane alternative

Dedicated bike lanes provide efficient multi-modal mobility along the corridor

Pedestrian alternative

Expanded sidewalks provide space for sidewalk amenities that complement areas of more intensive pedestrian activity

Cross-Section ElementMinimumMaximum
Sidewalk and Parkway8.5’10-12’
On-street Parking8’11’ (when no dedicated bike lane is provided)
Bike Lane6’, if provided8’, if other transit supportive amenities have been maximized
Travel Lane9’10’
Source of dimensions from Institute of Transportation Engineers (ITE)

75’ Right-of-way

Streets with a 75’-90’ right-of-way are typically collectors or minor arterials. They typically provide access between communities and may host limited residential uses with a greater prominence of retail or small office activities. Vehicular, transit, bicycle and pedestrian mobility should be equally prioritized, with urban design being maximized to ensure clear delineations between various transportation facilities. Depending on roadway width, parking configurations and traffic operations, medians can provide a unique character and safe haven for pedestrians.

Balancing vehicular and transit mobility

The cross-section should be designed to balance vehicular efficiency and transit and pedestrian safety

Landscaped median alternative

A landscaped median provides an attractive element that breaks up the length of pedestrian crossings

Commercial sidewalk alternative

The width for the sidewalk can be maximized to accommodate sidewalk amenities and heavy pedestrian volumes associated with local commercial activity

Cross-Section ElementMinimumMaximum
Sidewalk and Parkway8.5’20’
On-street Parking8’11’ (when no dedicated bike lane is provided)
Bike Lane6’, if provided8’, if other transit supportive amenities have been maximized
Travel Lane10’11’
Landscaped Median8’16’, if other transit supportive amenities have been maximized
Source of dimensions from Institute of Transportation Engineers (ITE)

100’ Right-of-way

Streets with right-of-way of 90’ or more are typically major arterials. They tend to provide higher-speed mobility to other parts of the region, and typically host large-scale commercial and retail uses. Major arterials generally consider vehicular mobility as the main priority. However, the right-of-way can often accommodate infrastructure that effectively integrates transit, bicycle and pedestrian mobility. Medians, buffers, dedicated paths and other urban design elements should be used at strategic locations to create comfortable multi-modal conditions and an attractive corridor character.

Pedestrian safety and comfort

On streets primarily designed for vehicular movement, infrastructure and design elements must be used to maximize access to transit and surrounding uses

Expanded median alternative

An expanded median provides a refuge area at crosswalks and enhances the character of highly traveled corridors

Expanded sidewalk alternative

Wide rights-of-way can accommodate comprehensive transit supportive infrastructure including wide sidewalks that provide additional buffering between pedestrians and vehicular traffic flow

Cross-Section ElementMinimumMaximum
Sidewalk and Parkway8.5’20’
On-street Parking8’11’ (when no dedicated bike lane is provided)
Bike Lane6’, if provided8’, if other transit supportive amenities have been maximized
Travel Lane10’11’
Landscaped Median8’16’, if other transit supportive amenities have been maximized
Source of dimensions from Institute of Transportation Engineers (ITE)

Multi-modal Networks

Streets should safely accommodate all modes of travel. All rights-of-way should have sidewalks on both sides of the street. Streets should be designed to accommodate safe bicycle use, especially on corridors that are identified as local or regional bike corridors. In this case, special efforts should be made to accommodate dedicated bike lanes.

Urban streets and suburban downtowns should accommodate several modes of access, including on-street parking, bike lanes and strong pedestrian networks

Suburban corridors and rural roadways should foster bicycle and pedestrian mobility that is safely integrated with high-speed vehicular traffic flow

Infrastructure Design Principles

Often, design specifications oriented toward vehicular movements compromise the integrity of local access to transit. To the extent possible, the following principles should be followed in areas where transit service is provided.

  • The width of traffic lanes should be limited to the minimum allowable standard. This will reduce pedestrian crossing distances and potentially slow traffic to mitigate the risk of accidents.
  • Curb radii should be kept to the minimum allowable standard. Wherever feasible, mountable curbs should be used to accommodate truck turning movements. This will reduce crossing distances for pedestrians when trucks are not present.
  • The design and installation of infrastructure and pedestrian amenities should be closely coordinated. Often, the expansion or replacement of infrastructure results in a compromised sidewalk network. Such improvements should be performed in such a way that a fully accessible sidewalk network is maintained.

Street Network Design Implementation Checklist

Guideline PrinciplesImplementation Tools
Design a well-connected grid pattern of streets that maximizes network connectionsLocal zoning regulations, local subdivision regulations
Plan small block sizesLocal subdivision regulations
Maximize multi-modal infrastructure within existing right-of-wayLocal subdivision regulations, local public works/engineering standards
Limit traffic lanes widths to the minimum allowable standardLocal subdivision regulations, local public works/engineering standards, D.O.T standards
Keep curb radii to the minimum allowable standardLocal public works/engineering standards, D.O.T standards
Coordinate the design and installation of infrastructure and pedestrian amenitiesLocal subdivision regulations, local public works/engineering standards, D.O.T standards