Summer 2002, p.17

Speed Humps Quiet Streets
Studies in New York and UK show speed humps reduce car noise

Well-placed speed humps are one of NYC's best weapons against aggravating traffic noise.The New York City DOT has a backlog of more than 1,000 speed hump requests. This means hundreds of community groups, churches and block associations are waiting in vain for the City to do something about their speeding and traffic safety problems.
DOT will not install anymore speed humps because of complaints from a handful of angry motorists (some of whom are on community boards). Of the 572 speed humps already in place, only a handful were installed in the last three years.

Make no mistake, speed humps work. They are by far the most effective device the city has to slow traffic and reduce crashes on neighborhood streets. Indeed, their very effectiveness is why short-cutting motorists do not like them.

Motorists' favorite complaint is that speed humps increase traffic noise. However, all of the research on the subject shows the opposite.

The New York City Department of Transportation's Speed Hump Noise Impact Survey measured overall noise and maximum level noise on 21 streets with speed humps and 19 adjacent control streets. The DOT found that the loudest noises decreased substantially after humps were installed, while background, or "ambient" traffic noise, remained unchanged.

A much larger British government study of speed humps and noise found that humps reduce both the maximum and average traffic noise. However, the study also found that installing humps on streets carrying 20% or more truck traffic creates more noise. The British study also found that, while speed humps do help reduce traffic noise, they should be installed in pairs and no more than 100 yards apart. The DOT's recent practice of installing single speed humps at long distances between humps encourages drivers to accelerate, creating noise.

  • The DOT is currently revising its speed hump policy and T.A. recommends the following noise guidelines:
  • Limit speed humps to streets with less than 20% truck traffic.
  • If a neighborhood street, which is not a designated truck route, has a higher than normal percentage of truck traffic, address the truck problem with enforcement, education and engineering and revisit the site to see if the ratio has been altered.
  • In the event of noise complaints, the DOT should conduct a noise survey.

Read the latest news on this subject.