Engineering Group Takes on High Speed Limits

Photo:  Insurance Institute for Highway Safety
Photo: Insurance Institute for Highway Safety

Speed limits on urban streets will no longer be set almost exclusively by how fast drivers choose to drive.

The National Committee on Uniform Traffic Control Devices, a powerful group of engineers, voted last week to require city transportation officials to consider “pedestrian and bicycle activity” when determining the speed limit on most urban and suburban streets. The changes will be incorporated into the Manual on Uniform Traffic Control Devices — perhaps the most important traffic engineering manual — when it is revised some time in the next few years.

Here’s why this is so profound: Current guidance on speed limits conform to the infamous “85th percentile rule,” which pegs the speed limit on any particular roadway to the speeds of the fastest 15 percent of drivers in “free-flowing conditions.” So if 85 percent of the drivers stay below 40 miles per hour and 15 percent of drivers exceed it, that becomes the speed limit, even if 40 miles per hour is a bit too fast for that roadway.

Critics say that such a rule raises the speed limit to what drivers want as opposed to what is safe for that road’s condition or context. The current edition of the Manual on Uniform Traffic Control Devices say that engineers may use other criteria — like the presence of pedestrians — in setting speed limits. But the new language orders them to use that information in addition to the 85th percentile rule.

“It has the potential to have a significant impact,” Peter Koonce, an engineer with the City of Portland and a sitting member of the NCUTCD, told Streetsblog.

The engineering group also voted to strike language that said the speed study should be conducted in “free-flowing” traffic conditions.

“That’s really a recipe for getting higher speeds,” said Koonce.

The League of American Bicyclists called the changes “welcome improvements,” but the organization added that NCUTCD should have gone further.

The rule changes come as there has been growing awareness of the dangers of speeding, especially as traffic fatality rates have been surging. In 2017, the National Transportation Safety Board sounded the alarm about the issue and suggested rethinking the 85th percentile rule.

Speed management is important for everyone’s safety, including drivers. But it can be especially critical for pedestrians. A pedestrian struck by a car at 40 miles per hour has a 55 percent chance of surviving compared to a 88 percent chance at 25 mph.

NCUTCD refused to provide Streetsblog the approved language for several weeks so this reporting relied on third-party documents.

191 thoughts on Engineering Group Takes on High Speed Limits

  1. Using terminology that’s used in the studies you cite is “twisting the nomenclature.” Right. I can see why you seem ignorant of the decades of research that contradicts the NMA’s fringe positions.

  2. Right, and those same local politicians who have zero say in state road planning somehow influenced the road design to make sure cars travel at high speeds so they could ticket them and raise revenue?

    Again: it’s not a conspiracy, Duke. It’s Occam’s razor of the reasons already supplied to you.

  3. A real question for you. Knowing that the actual speeds did not change – what was the SAFETY value of enforcement?
    James C. Walker, National Motorists Association

  4. In reality, 100% of car accidents are “speed-related”. If cars did not move at all, there would be no car accidents.

    What the for-profit ticket industry twists, and seems to have convinced many others to twist, is the difference between the actions that are likely to cause crashes – and the other incidental circumstances. It is almost like blaming “right-lane-related accidents” because so many happen in those areas.

    James C. Walker, National Motorists Association

  5. Posted speed limits have little effect on congestion because they have almost no effect on the actual travel speeds. (Hint – that makes your attempted 2nd paragraph conclusion void.)

    Have you truly never seen decimated downtown areas because they became too hard to navigate, and noted the thriving shopping areas a couple of miles out?

    Again – cities are FREE to re-engineer the streets to achieve voluntary and permanent changes in the actual travel speeds, so long as they accept the possible negatives.

    James C. Walker, National Motorists Association

  6. When engineers leave yellow intervals about one second too short to leave the violation rates at camera intersections 60% to 90% higher than they would be, they have joined the for-profit racket supporters. When they don’t insist on good lighting, uniform signage, and well maintained pedestrian crosswalk markings – particularly at mid-block ones – they have refused to fix obvious engineering errors that raise risks for pedestrians.
    James C. Walker, National Motorists Association

  7. That isn’t worth answering because – if it is a real question – it shows how little you understand of the realities.
    James C. Walker, National Motorists Association

  8. I agree this discussion has gotten pretty tiresome. Maybe if you understood more about the insurance industry driven multi billion dollar for-profit ticket industry, many of your views would change.
    James C. Walker, National Motorists Association

  9. As you seem ignorant of the decades of research that does.
    James C. Walker, National Motorists Association

  10. If the speeds don’t change, that just means the fines are far too low.
    But the ability to punish the criminals is essential.

  11. Keep the 85% rule, but actually use it.

    What is the 85th percentile speed when you include the pedestrians and bicyclists?

  12. Engineering can help, and will reduce the speed for most, but it is far from a universal fix. The approach must be multifaceted.

  13. There is literally no downside to it.

    If it reduces the speed of anyone, there is a positive safety effect.

  14. You might recall that not long ago a PE informed you directly that the research you use to support your dogmatic views was flawed.

    You almost never provide citations for your claims when asked, and when you do provide citations the research is often a decade (or more) old. You typically misrepresent the articles (as with the FHWA study on “critical reasons” for crashes) or seem to have not read them (as with the Montana study). You admit that you typically get your information from “mainstream articles” that are less interested in the science and more about generating clicks.

    If you’d like me to link studies supportive of claims I’ve made, I’ll happily supply them. Nothing I’ve said is particularly controversial to those who follow transportation research. You’d know that if you weren’t mired in mid-20th-century dogma.

  15. If speeds are the same and there is no safety benefit, then it is a for-profit racket – essentially government larceny. No one should support government larceny.
    James C. Walker, National Motorists Association

  16. We need to quit this exchange, we are going over the same ground over and over. The basic principle that changing posted limits does not change actual speeds has been known for over 75 years – and remains true.
    James C. Walker, National Motorists Association

  17. It isn’t larceny. It is taking money from criminals and using it for the public good.

    The only problem is that they aren’t taking enough of the money to have a large enough effect.

  18. You should be more generous. Other people regularly humor your questions and respond to your comments despite your obvious biases and pathetic level of knowledge.

  19. I’d probably give more credence to your conspiracy theory if you didn’t regularly say silly things that are easily falsified and attempt to steer the conversation away from any proven methods to improve safety if they would hold law-breaking motorists accountable for the dangers they create.

  20. I agree, if nobody choose to drive, the tens of thousands of people who die every year as a result of that choice would be alive today.

    You seem to be missing the point that the 30%+ figure is based on police reports in which they consider speed a factor or in which a citation for speeding is issued. That’s very different than what you’re claiming.

    It’s funny that you expect people to believe you, a lobbyist with clear biases, over the engineers, planners, researchers, and safety advocates that regularly disagree with your propaganda.

  21. “Maybe if you understood more about the insurance industry driven multi
    billion dollar for-profit ticket industry, many of your views would

    Allow me to translate: “Maybe if you subscribed to my conspiracy theory and ignored conflicting facts, many of your views would change.”

  22. So why do you think posted speed limits 5 mph below the 85th percentile speed resulted in fewer crashes in the study you cited?

    We can quit this exchange when you stop spreading misinformation and working against measures that will save lives.

  23. Were you deprived of oxygen at birth? That’s “freedom” I can do without. Freedom to wreck the planet. Freedom to help sell my country to subhuman Islamic savages in exchange for oil. Freedom to make walking and cycling more dangerous to my neighbors. Fuck your freedom, moron.

  24. Speed sensors and engine governors can be remotely controlled to maintain posted speed limits or reduced under certain circumstances. Many public agency or rental cars already have them installed to monitor drivers patterns. No U.S. court has ever ruled that car manufacturers bear responsibility for damages caused by their product operating as designed. In other words, top speeds, killer grills, limited views, etc. Only when some part fails to work due to manufacturing flaws, from High and Mighty an excellent book..

  25. I ran into parked cars a couple of time- once while playing street football (looking up) once while bicycling in a head wind (looking down), so collisions would still occur. Less damage though.

  26. One district court in northern Cali set that precedent according to an article I read several years ago, (must have been upheld if challenged, but possibly wasn’t challenged.)

  27. I did the same in 1964. 🙂
    I fell asleep on my bike riding to my apartment after my last college final that year – having been up for over 50 hours – and ran into the back of a parked car. Fortunately the speed was very slow, so I wasn’t hurt.
    James C. Walker, National Motorists Association

  28. You’re describing a liberty, not a freedom. US law strives to preserve both but does recognize the unfairness when one person’s liberty impinges on another’s freedom. For example the liberty to drive fast and reckless impacts the freedom from harm that other street users should be able to enjoy. That’s why we have speed limits and laws governing the responsibilities of people on the road. We are a free country but that doesn’t mean our streets should be a free-for-all.

  29. In the case of Whitehouse Ohio, the village is annexing rural roads then being ‘shocked’ that motorists don’t see any difference in the road or development just because the village limit signs moved and the village posted 35-mph signs. It’s easy to google-street-view the road and see for yourself. It’s a common profit-taking strategy/conspiracy in small towns.

  30. Mine was a ride I did most days from community college in 76, always heading home into steady headwinds on a road where cars weren’t supposed to be parked. Easier just to look down at the white line and pedal on, but one was broken down with its trunk open, cut my face pretty well when I pitched into the trunk against an open tool box. The driver came around from the engine, shocked and handed me a dirty rag to stop the bleeding. I was so stunned that I asked where a pay phone was and he directed me up the road, then drove off. Must have fixed what was broken.

  31. Sure, cities change. Your proposition that this was all part of a master plan to screw people in cars (think real hard about that for a second) is preposterous and does nothing to forward the discussion to make our cities safer or more efficient.

  32. They’re not a free-for-all; the 85th percentile rule just keeps local government from turning the traffic stream into a revenue stream.

  33. I’m guessing that you live in a dense, congested, highly-urbanized area, not the ‘burbs and styx where I live and drive.

  34. Hey, Duke,

    I’m not challenging the accuracy of the reporting about this stretch of road or that some roads ‘feel’ like they should have a higher posted limit, nor that local governments use these to make rev.

    I AM calling you batshit crazy for stating that this some sort of desired result involving a conspiracy of all parties within the transportation system. Also, I calling you paranoid, and also calling you out for insinuating that speeding drivers are being victims.

    Lastly. I have never had cancer but I know a lot about it. You don’t have to experience something first-hand to know things about it.


  35. Potato, potahtoe; doesn’t change the fact that it’s regular, repeated, historical, and pervasive exploitation of citizen-motorists (the vast majority of the population) for profit.

  36. Sincerely asked again, but the post never appeared:
    So why do you think your Montana study found speed limits 5 mph below the 85th percentile resulted in fewer collisions and fewer fatalities? I’m genuinely curious.

    The study is too small to be reliable. There is one from Auburn University saying the societal costs of red light violations up to 3.5 seconds into the red are $0.00 because they don’t cause accidents. That study is too small to be reliable – and I say so in posts. It is easy to see why red light violations up to 1.0 seconds cause no accidents and it is likely at most intersections that up to 2.0 seconds into the red is harmless to safety. But up to 3.5 seconds based on that small study is not defensible in my view.

    I am not re-engaging because Sincerely will not acknowledge the fact that so many venues use improper traffic laws and enforcement as profit centers. But it was a legitimate question.

    Jame C. Walker, National Motorists Association

  37. No, I actually do live in a very auto centric suburb with wretched mass transit, virtually no enforcement of speed limits anywhere and patchy to no sidewalks or street lighting. If drivers weren’t put above the law to the degree they are here I would probably not think in such an extreme way.

  38. Pro-profit cities? Speed trap “rackets?” How about cities that give a damn about the lives fo their residents?

  39. Ugh. I’ve got a decent middle-class neighborhood with sidewalks, 500′ from a hike/bike trail, and a quarter-mile from a bus stop (handy for when I work downtown). Of course it took months of looking to find it.

    Are you biking to work? Mine is recreational to the library and around the village.

  40. The key here is this procedure noted above.
    “…keeping the amount of enforcement well below what would cause most drivers to stay below XX mph when the conditions make XX plus 10 or 15 mph feel AND BE safe and comfortable.”

    It would be EASY to set up enforcement regimens that would actually cause almost every driver to be under or very close to a limit set well below what feels safe and comfortable. The “problem” with that approach is it would be a huge cost item in the city budget with almost no offsetting ticket revenue. Cities do NOT do this. They apply enough enforcement to tell the public “we are doing something about the speeding problem (a problem the city created by posting a low limit without changing the engineering of the street) – but an amount that guarantees high profits to the city above the enforcement costs. It is a racket.

    James C. Walker, National Motorists Association

  41. So here’s the timeline:

    1. Lobbyist JCW makes a claim.
    2. He is asked for citations.
    3. He references a study.
    4. It is pointed out to him that the study doesn’t say what he’d claimed and that its results directly contradict one of his frequent assertions.
    5. JCW then says the study is too small to be meaningful and tries to change the subject.

    I’m not sure how anyone takes your fringe group seriously.

  42. @DukeGanote:disqus And yet, it’s easy to avoid the fines: obey the speed limit. If municipalities learn their budget can’t be met by tamed driving speeds, then municipalities should sort out a better way to raise revenue. Wouldn’t it be a sensible act of civil obedience to drive within the limit?

  43. Small studies can support the general principles that multiple other studies have revealed. But single small studies should not be taken as definitive for the details. I made it clear neither the Penn State one in Montana on speed limits nor the Auburn University one on yellow intervals should be taken as definitive for their specific findings.
    Jame C. Walker, National Motorists Association

  44. My own traffic studies demonstrated what others have observed for decades and decades: very few people care what the signs say; they drive the road, not the signs. For example when the speed limit was 35-mph on SR 835, hardly one of 100 drivers held to the obviously silly limit on a 4-lane, rural divided road. So the better question is: why do supposed-representative governments criminalize the vast majority of of citizen-motorists and enact exploitative laws?

  45. My own traffic studies demonstrated what others have observed for decades and decades: very few people care what the signs say; they drive the road, not the signs. For example when the speed limit was 35-mph on SR 835, hardly one of 100 drivers held to the obviously silly limit on a 4-lane, rural divided road. So the better question is: why do supposed-representative governments criminalize the vast majority of of citizen-motorists and enact exploitative laws?

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