The 85th Percentile Speed Limit Rule is Good for You;

Now you Can Forget About IT

Art Slabosky, PE

Member APBP, ITE, LMB (League of Michigan Bicyclists)

Like these Wild Animals’ Behavior, Drivers’ Speed Reacts to Conditions, not Instructions

• Sources from Both ends of Walkability spectrum Attest to the Limited Power of Changing Speed Limits Per Se: (sources available)

• NMA • ITE • FHWA’S Pedestrian action plan: • Trafficcalming.org (speed limit unmentioned) • Eric Dumbaugh (Safe Streets, Livable Streets)

• THEN WHY DO WE STILL FACE THIS:

You Won’t Lower the Speed Limit?

Don’t you care about safety?

From Blogs, Listserves and E-mails

• One for the dustbin, the 85th percentile rule in Traffic

Engineering. (5)—Streetsblog DC . Copenhagenize.com: Labels and engineering report “so Stupid”

• …“the idiocy of using the 85th percentile to set speed

limits” (7) Peds Atlanta on APBP listserve.

• …the old 85th percentile trap…a well greased, dark, sleezy (sic), slippery-slimey (8)

• Why do these Irate people hold sway so often , despite research from their own side confirming the facts.

Why such insulting rhetoric for one practice and those who practice it? Especially when those who disdain the practice Have NO competing method?

Law=Results, SOMETIMES

• Passing a law and posting a sign may not • yield the desired results.

What does This Sign Tell You?

Misplaced Advocacy—How do we get it? +Illusion that speed limit equates to travel speed. +Don’t want to cooperate with “the enemy.” +Double Standard Peds/bikes vs. drivers. +belief that limit sign endorses existing speed. +Desire to “send a message.” >>>LEADS TO UNDESIRED CONSEQUENCES (following courtesy Michigan State Police)

Example Speed Limit Political Change

When you Criminalize the Majority

+ Allow police to apprehend any driver they want, regardless of speed: can choose for instance, long hair, wrong race, youth, bumper sticker, rusty old car. + Citizens have trouble assessing their own safety because they receive a false message about vehicular speed. + Enforcement efforts concentrated on one thing; Forget about crosswalk violations, school zones etc. The police have their mandate on “speeding.”

AND THE BIGGEST PROBLEM IS:

TRAFFIC CALMING EFFORTS END WHEN SIGNS GO UP AND OFFICIALS DECLARE A JOB DONE.

• Local officials who rush to lower speed limits are NOT your friend. • They “Declare Victory and go Home”

• Why would your city council want to implement an ineffective measure? 1. Changing a road’s hardware to foster lower speed costs money. 2. 2. Causing a steady flow of criminalized drivers makes easy money for the city, AND gets you off their back, if you allow it. CASE HISTORY

• Benefits OF SETTING 85TH PERCENTILE LIMIT: Featuring my own town, East Lansing, Michigan:

• Speed limit set on State Trunkline (now Bus-I-69) at 45 in 1960’s. • Reduced from 45 to 35 mph after boy struck and killed on his bike late

1970’s, followed by an outcry to DO Somethng.

• Speed limit remained for more than 30 years at 35, while speeds remained in mid-40’s.

• In 2006 Michigan Legislature passed PA 85 which required scientifically set speed limits.

• In response to a Speed study , MDOT and State Police ordered a return of Speed Limit to 45 on Bus-69.

About East Lansing

After much protest and Vilification of State by the City etc. the 45 was posted.

• Results: Better allocation of police efforts (not just in terms of

traffic) • From news article from August 11, 2008: • Crime in East Lansing crime hit a • 28-year low. • Speeding tickets 2008 vs. 2007 were down by 378 , and traffic

crashes were down by 531 from four years earlier. • Speed profile of drivers on bus-69 was virtually unchanged. (as in the example in the slide)

East Lansing Crash Record Three Years Before and Three After

Speed Limit Increase on Bus-69

Bus-69 The Whole City Crashes People Crashes People • Before 317 789 4232 10497 • After 312 803 3380 8416 %Change -2 +3 -20 -20

The Big Bonus:

• Finally a sidewalk was built on both sides of the highway in response to the “speed” increase.

• WHY? • When signs said 35, city was content to give

false impression and people never demanded sidewalk.

• Facing the fact of 45 mph car traffic brought demand for the sidewalk.

What if Speed limits WERE Not set Politically?

.Only deserving drivers would be ticketed for speed violations. • Rules dependent on speed could rely on posted speed limits. E.g.

Yellow signal interval.

• .We would have actual knowledge of the relationship of • Crashes to Travel Speeds.

• These terms would become meaningful: • “speed-related (crash).” • “speed compliance.” • “excessive speed.” And finally SPEED LIMIT itself .

Even 85th-Mockers may really not be talking about changing Speed Limit alone.

• Here is a later part of the letter from the consultant who referred to the 85th rule as the

• “sleezy (sic), slippery-slimey critter etc.”

• “unfortunately this (reducing speed limits) means you will need to apply some clear thought and advanced methods of controlling speed, such as appropriate street designs and traffic operations…”

• Lesson: We are ALL looking for the same thing, so leave “speed limit” alone as a strategy. Think in terms of “speed.”

How about THIS Engineer? • Interview with Engineer Mike Sewell: • …“Motorists were driving too fast through the

area, so by taking away two of the four lanes for vehicles and reallocating them for bicycles and pedestrians, we were able to slow down vehicle speeds, provide residents with more transportation options, and increase overall safety. Now people are out walking or biking rather than traveling a few blocks by bus. (9)

• .. No mention of speed limits—is that a problem? • When you reduce speeds through engineering

measures, the REDUCED SPEED LIMIT CAN THEN BE PROPERLY POSTED.

Conclusions

• Lower speed limits alone do not provide lower speeds, as much as we

would like that. • Establishment of speed limits as reflections of actual travel speeds does

not compromise safety and can improve it. • Speaking in terms of speed limits instead of speed can lead political

leaders to a wrong solution and wrong sense of accomplishment. The 85th Percentile speed limit rule provides road users with a threshold to highlight deviant drivers, AND as a base for efforts to modigy the road users’ behavior if we wish to do so.

WELCOME TO YOURTOWN WILD ANIMAL SAFARI PARK

Welcome to YOURTOWN Petting Zoo

Welcome to YOURTOWN Petting Zoo

Sources • (1) Methods and Practices for Setting Speed • Limits: an Information Report, by ITE, 2012. • (2) Developing a Pedestrian Safety Action plan,

FHWA, presented in Flint, MI 2007. • (3) Safe Streets, Livable Streets: A Positive

Approach to Urban Roadside Design,Eric Dumbaugh PHD paper, 2005

• (4) The Truth About Speed Limits, by James Baxter, www.motorists.org, speed-limits/truth

• (5) “Streetsblog Network, One for the Dustbin, the 85th Percentile Rule,”November 16, 2012.

• (6) Copenhagenize.com “The 85th Percentile Folly”, November 16, 2012

More sources

• (7) Comment on APBP (Association of Pedestrian and Bike

Professionals) listserve, June 15, 2008. • (8) E-mail from Dan Burden to a member of East Lansing, MI,

City Council, (and cc’ed to a large pedbike audience) March 2, 2004.

• (9) “Be the Advocate for Complete Streets”, • Interview with Transportation Engineer Mike • Sewell, , May 2013.