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City Limits Index

City Limits
Guide Navigation
Combining Tools

Combining Tools

Cities can combine these proactive speed management strategies to create safe conditions for their city.

EXAMPLE COMBINATION: CITY A

City A has explicit authority to set default speeds and has chosen to set a citywide default limit of 25 mph on all streets. In addition, they have identified a few high-crash corridors and have set 20 mph corridor limits on those streets to reduce fatalities and injuries. They also have established 20 mph slow zones in key areas around schools or parks to provide additional protection for children.

EXAMPLE COMBINATION: CITY B

City B has explicit authority to set default speed limits and has clear differentiation between major or arterial streets and minor or local streets. They have chosen to set category speed limits at 25 mph for arterials and 20 mph for non-arterials. Like City A, they may choose to also establish slow zones in key areas.

EXAMPLE COMBINATION: CITY C

City C does not have explicit authority to set default speeds. The state requires a speed study but does not lay out an explicit process. They have chosen to conduct a bulk engineering study and to use a locally-defined process for setting speeds by street category. At the same time, using authority to set speed limits on a case-by-case basis, they have conducted a Safe Speed Study to determine appropriate speed limits for a few priority corridors.

 

RECENT NOTABLE LEGISLATIVE CHANGES

 

 

POLICY HURDLES

A city’s ability to change speed limits is impacted by rules and practices around enforcement, signage, and design requirements.

Enforcement

A city’s ability to enforce the posted speed limit depends on whether speed limits in the state are Absolute, Prima Facie, Basic Speed Law, or a combination of the three. When drivers are ticketed in a state with absolute speed limits, the ticket will typically stand on face value. In states with prima facie, or presumed, speed limits, drivers can contest tickets in court on the basis that their speed was safe for the conditions. In basic speed law states, drivers are required only to travel at a safe speed, regardless of the posted speed limit. A growing body of evidence shows that drivers respond to posted speed limits even without changes to enforcement; cities may want to make speed limit changes even when enforcement is difficult.

Design

In some states, cities must implement physical design changes to streets in order to justify lower speed limits. Requiring engineering changes before cities can change the posted limit can make it difficult for cities to change speed limits on a large number of streets because of the cost. Other cities must reduce speed limits before they can make design changes, since the design speed is set in relation to the posted speed on a given street.

Signage

In some states, a city must install a sign on every block if the posted speed limit is anything other than the citywide default. This is feasible when the city lowers the limit on a small number of segments, but becomes prohibitively expensive at a large scale (e.g., across all residential streets).

References