What About Speed Humps?

By Dom Nozzi

I have mixed and declining feelings about the usefulness of speed humps—those relatively large asphalt bumps in the road designed to slow down (calm) cars.

Here is what I had to say in my Road to Ruin book about humps:

“Speed humps also reduce vehicle speeds and at the same time reduce accident rates, or at the least do not increase them, according to the Institute of Traffic Engineers (ITE).  Humps cause drivers little or no discomfort if we are going less than 25 mph, and they need to be spaced close enough to each other so that we cannot speed from one to the next. The ITE has found that despite concerns about liability, vehicle damage, and emergency vehicle impacts, these problems have not occurred or have been found to be insignificant when considering the positive effects of humps.”

“In fact, such modest physical reconfiguration of streets has proven the only reliable and cost-effective way to slow and control traffic.  Despite the conventional wisdom, neither stop signs nor posted speed limits affect overall traffic speeds or control speeding.”

However, since I wrote that book, I have come to learn from Dan Burden, the road diet and roundabout guru, that humps tend to be over-used by most communities, and often degrade the quality of a neighborhood street. Dan also makes the important point that unlike horizontal interventions such as chicanes and bulb-outs, vertical treatments such as humps can be quite detrimental to emergency response vehicles. He generally discourages the use of humps, and I agree with him that there are a number of calming treatments that are far superior to humps. He points out that elected officials tend to over-use humps because they are relatively cheap.

And therefore a low-cost way to placate citizens angry about speeding traffic.

In general, I am thoroughly convinced that one of the most effective ways to improve neighborhood and town center quality of life, safety, and economics is to slow motor vehicles using calming methods. I particularly like on-street parking and relatively narrow travel lanes. My favorite street type is the “give-way” street, where motorists are obligated to “give-way” to an approaching car because two cars cannot find the width to pass each other unless one moves aside. This obligates much safer, attentive, slower speeds.

And therefore more humanized vehicular travel that is much more conducive to the human habitat.


Visit my urban design website read more about what I have to say on those topics. You can also schedule me to give a speech in your community about transportation and congestion, land use development and sprawl, and improving quality of life.

Visit: www.walkablestreets.wordpress.com

Or email me at: dom[AT]walkablestreets.com

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Filed under Urban Design

3 responses to “What About Speed Humps?

  1. Hey Dom. I am a transportation planner and I totally agree with you about humps. Municipalities like them because they are cheap because they don’t interfere with drainage whereas horizontal deflection is more likely to create issues with drainage. When I see speed humps I was think it is an admission of failure or imagination that nothing else would work. That’s why is annoys me so much when municipalities still have overly wide local street standards that they insist on. New development should be using narrower streets and on street parking to create natural pinch points. The only time vertical deflection has a useful role to play is if you are emphasizing a pedestrian crossing or intersection where pedestrians cross and you are raising up the road level to that of the sidewalk.

  2. Thanks, Tim. I like the your comments. I’m getting ready to self-publish a book that discusses this issue.

  3. Randall

    I only have a little problem with the on-street parking, and this might be because I live near a pub. But, in parking on the street, I am getting an increased number of scratches and other marks on my vehicle. However, if the problem were only scratches, I wouldn’t complain too much, as I have a bit of touch-up paint on hand.

    My problem is that one morning I went to get into my car and to my dismay my side-view mirror was completely shattered, though attached (to my relief), and the side of my car was dented. Anyway, just thought I’d pass on another view…sort of.


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