Excessive speeding in cities can be particularly deadly for vulnerable road users, especially on busy arterials with high 

volumes of vehicle, pedestrian, and bicycle interaction. Only five out of 10 pedestrians will survive a crash with a vehicle 

traveling at 42 miles per hour (mph).1

Transportation practitioners use a variety of strategies to manage speed, 

and lowering speed limits citywide is one of those strategies. However, 

simply lowering the citywide speed limit isn’t always enough to slow 

drivers—a wide travel lane design and unobstructed views on many city 

arterials encourage speeding by making drivers feel that it is safe to speed. 

REDESIGNING CITY ARTERIALS

Many cities incorporate countermeasures into street design to reduce vehicle speeds and contribute to a complete 

streets environment—one that enhances the safety and mobility of all road users. Examples include:

Lower Citywide Speed Limits and Design Changes

Safer city arterials for all road users

STREET DESIGN

SPEED MANAGEMENT 

Source: FHWA based on AAA study1

Raised Pedestrian Crosswalks

Often installed at mid-block 

crossings, raised pedestrian 

crosswalks extend across the 

entire width of the roadway. 

Pedestrians cross at the same 

level as the sidewalk, making 

them more visible to drivers. 

Approach ramps cue drivers to slow down, giving them 

more time to react near pedestrians.

Curb Extensions

Curb extensions reduce the 

width of the roadway by 

extending the curb into the 

parking lane. This shortens 

pedestrian crossing distances 

and reduces the time needed 

to cross the street. Drivers are 

encouraged to slow down when approaching intersections 

and mid-block crossings, making turns, and traveling 

through intersections.

Lane Reduction

Lane reduction reduces the 

number of travel lanes on a 

multilane undivided roadway, 

which can affect a driver’s 

choice of speed. Also known 

as a road diet, the extra space 

can be reallocated to add 

dedicated turn and bus lanes and other countermeasures 

such as pedestrian visibility and crosswalk enhancements. 

Lane Narrowing

Lane narrowing using 

pavement marking techniques 

reduces the width of the travel 

lane. It frees up space for traffic 

calming measures such as 

widened sidewalks, extended 

curbs, and chicanes. Also called 

a lane diet, this can force slower vehicle traffic, make drivers 

more aware of surroundings, and give drivers more time to 

react to pedestrians at intersections and crosswalks.

 1 AAA Foundation for Traffic Safety, Impact Speed and a Pedestrian’s Risk of Severe Injury or Death (Washington, DC: 2011).

Source: SDOT, Raised crosswalk, FLKR

Source: FHWA

Source: FHWA

Source: FHWA
http://safety.fhwa.dot.gov

FHWA-SA-22-13

SPEED MANAGEMENT: LOWER CITYWIDE SPEED LIMITS AND STREET DESIGN STREET DESIGN

 Reduce excessive speeding

 Increase compliance with 

reduced citywide speed limit

 Reduce number and severity 

of injuries from collisions

 Removed one lane of traffic in 

each direction

 Added dedicated bus lanes and 

center turn lanes

 Narrowed travel lanes with curb 

and sidewalk extensions

 Improved signage for better 

visibility of lowered speed limit 

 52% decrease in speeding 

northbound; 28% decrease 

southbound

 15% decrease in collisions overall

 30% decrease in injury collisions 

 40% decrease in pedestrian and 

bicycle collisions

GOALS TREATMENTS RESULTS*

* Source: SDOT, Rainier Avenue South Safety Corridor: Rainier Pilot Project Evaluation.

SPOTLIGHT ON SEATTLE: REDESIGNING A CRASH-PRONE ARTERIAL

After lowering the citywide speed limit from 30 to 25 mph, excessive speeding on Rainier Avenue South was still 

a challenge. Seattle Department of Transportation employed street design changes to help improve speed limit 

compliance and road user safety on Rainier Avenue South.

LEARN MORE

 FHWA’s Traffic Calming ePrimer

 USLIMITS2: Set reasonable, safe, and consistent speed limits for specific road segments

 Rainier Avenue Improvement Project

Redesigning Rainier Ave S to be self-enforcing and adding 

speed management countermeasures has improved 

compliance with the lowered posted speed limits.

 Jame Le, SDOT

BEFORE AFTER

Source: Seattle Department of Transportation