Pedestrian-Friendly Vehicle Speed
Vehicle speed affects pedestrians’ safety in a number of different ways.
Likelihood of Collision
“Faster speeds increase the likelihood of a pedestrian being hit,” according to Federal Highway Administration’s Pedestrian and Bicycle Information Center.
Severity of Collision
If a pedestrian is hit by a vehicle traveling at 40mph, he/she has a 15% chance of survival, but if the vehicle is going 30mph, chance of survival increases to 55%, according to the Federal Highway Administration’s Pedestrian Facilities Users Guide: Providing Safety and Mobility (2002).
Last, motorist compliance with yielding to pedestrians in crosswalks is significantly improved by reducing vehicle speed to below 35mph, according to the federal report Improving Pedestrian Safety at Unsignalized Crossings.
Special Speed Zones
We’re all familiar with a School Zone, which requires a speed limit of 25mph when children are present.
West Windsor also has a 15mph speed limit at the Princeton Junction train station parking lot, to improve safety for commuters. Somewhere in these speed limits is a policy judgment regarding the capacity of our children and of our commuters to safely navigate traffic in these zones.
Horse riders also rate a special speed zone under New Jersey state law, 25mph. In addition, motorists must follow the rider’s hand signals as to when it is OK to pass. Many people today are not familiar with horses’ unpredictability, so please remember to give the horse and rider plenty of room when passing – going more slowly and quietly past is recommended for everyone’s safety.
Roadways Designed for Speeding?
According to NJDOT’s Smart Transportation Guidebook, many different factors come into play when choosing a desired operating speed for a roadway. From the discussion of speed:
“Desired operating speed is best explained by its relationship to three other concepts of speed: operating speed, posted speed, and design speed.
Operating speed is the speed at which a typical vehicle operates, commonly measured as the 85th percentile speed of all vehicles.
Posted speed is the legal speed limit on a roadway. It is often set without any means of self enforcement, and drivers tend to travel at what they perceive as a safe speed regardless of the posted speed. Fewer than a third of drivers go the speed limit on urban and suburban arterials.
Design speed (as defined in the AASHTO Green Book) is the speed used to determine various geometric design features, including horizontal curvature, gradient, superelevation, stopping sight distance, and, for rural highways only, lane width.
Historically, New Jersey has required the design speed to be 5 mph above posted speed for existing roadways, and 10 mph for new roads.
The greatest drawback to the existing design speed approach is that drivers usually drive as fast as they believe the road can safely accommodate.
Existing policy may thus encourage operating speeds higher than the posted speed limit and/or selected design speed in an area.
In the interest of highway safety, it is desirable to have a stronger relationship between the posted speed limit, design speed, and operating speed. Therefore, this guidebook recommends that the desired operating speed for most roadway types be the same as the design speed, and also the same as the posted speed.”