Posted Aug 10, 2020, 6:17 PM
|
|
Registered User
|
|
Join Date: Aug 2002
Location: Toronto
Posts: 52,200
|
|
It's Time To Reconsider How Speed Limits Are Set
Why Slower Commutes Can Be A Good Thing
Aug 5, 2020
By Tiffany Chu
Read More: https://www.forbes.com/sites/tiffany.../#263ae42f1ce5
Quote:
.....
The reality is that speed limits on most U.S. streets are not chosen based on what speed is safest for everyone using the roadway they are set by the speed at or below which 85 percent of the motorists drive on a given road, an outdated guideline promoted by the Federal Highway Administration (FHWA). Today’s speed limits are not set for our safety. They are, in fact, making us less safe.
- When following the 85th percentile guideline, engineers recommend a speed limit that falls near the 85th percentile of the average speed naturally observed on a roadway. The method assumes two things: 1) that drivers pick a speed that is safe for the road conditions and 2) that it is safest to drive the speed desired by fellow drivers. Say you live along a state route in a rural area. If 85% of drivers drive at or below 55 mph, 55 mph would become the starting speed limit for said road. Engineers can then make adjustments to the starting speed limits based on neighborhood factors such as physical design of the street or volume of pedestrian traffic. — Researchers from University of California Institute of Transportation Studies point out that there is no empirical study demonstrating that the 85th percentile speed optimizes safety, but the guideline is difficult to get around because of its presence in the FHWA’s Manual on Uniform Traffic Control Devices (MUTCD) and promotion by the Institute of Transportation Engineers (ITE). For decades, transportation engineers routinely follow guidelines outlined by the MUTCD and ITE as standard practice.
- Simply lowering speed limits may not be enough, though. Drivers don’t sufficiently reduce their speed unless the roadway is designed and engineered to make them slow down. The 85th percentile guideline was actually born from this knowledge, if speed limits are reduced too far below the average speed, crashes can increase because drivers stop paying attention. Policy makers and advocacy groups are proposing new paths forward. The National Association of City Transportation Officials (NACTO) just released a recent report, City Limits, which calls for designing slow zones, along with setting default speed limits on many streets at once, and using conflict density and activity level to set corridor speed. — The critique of the 85th percentile is not new, advocates have long called for its removal. What is new is broad-based support and awareness as evidenced by NACTO’s City Limits report, and government initiatives such as CalSTA’s Zero Fatalities Task Force. These efforts are major steps forward to unwind this harmful practice of speed-setting, and reorient around neighborhood and design considerations.
.....
|
Examples of engineering measures to slow vehicular speeds for safer streets. Peter Biczók & Kelsey Jones, Remix
Additional examples of engineering measures to design more inclusive streets - for people of all ages and abilities, using a variety of modes. Peter Biczók & Kelsey Jones, Remix
__________________
ASDFGHJK
|