March 24, 2009

Slow It Down!

New book addresses how to calm traffic with humps, lumps, bumps, and other techniques.

CHICAGO — An estimated 100,000-plus speeding tickets are issued daily across the U.S. Communities must address how to make their streets safe not just for automobile users but for other users such as pedestrians and bicycle riders.

The U.S. Traffic Calming Manual is the first comprehensive how-to manual developed specifically for U.S. communities to slow down traffic or to reduce traffic volume on a given road. The manual is published by the American Planning Association's Planners Press in association with the American Society of Civil Engineers (ASCE) Press.

The authors, Reid Ewing and Steven Brown, have more than 40 years of combined experience in the field of transportation planning. Ewing is a professor of City and Metropolitan Planning at the University of Utah. Brown is a senior principal at Fehr & Peers and the former director of Transportation Planning for the City of Sacramento.

The U.S. Traffic Calming Manual provides communities with a number of options instead of a single one-size-fits-all solution. The manual takes a reader through the process of establishing an effective program, determining which traffic calming devices to use, and designing the selected devices to achieve the desired outcome.

Emphasis is placed on physical traffic calming measures — volume control and speed control — because they have a proven effect at reducing speeds, cut-through volumes, and collisions. Volume control measures preclude one or more movements along a street or at an intersection and speed control measures moderate speeds. Some physical traffic calming measures include:

  • Full Street Closures — The use of landscaped islands, side-by-side bollards or other obstructions that leave an opening smaller than the width of a passenger car.
  • Forced-Turn Islands — Raised islands on approaches to an intersection that block certain movements.
  • Speed Lumps — Rounded or flat-topped raised areas placed across the road with wheel cutouts for large vehicles like fire trucks to pass with minimal slowing or rocking.
  • Chokers — Curb extensions or edge islands at midblock that narrow a street at a certain location.
  • Neckdowns — Roadway extensions that reduce the width from curb to curb.

Test your knowledge of traffic calming measures.

According to the authors, the U.S. is at least a decade, if not two, behind Europe in implementing traffic calming techniques. "American cities are beginning to recognize the importance of taming traffic to make roads safer for all users," said Ewing. "It is always cheaper to implement traffic calming measures when first constructing the street than to go back and add calming measures later."

Several progressive cities are highlighted in the manual for their traffic calming efforts. The authors highlight the work of Sacramento, California; Austin, Texas; Bellevue, Washington; Phoenix, Arizona; Eugene, Oregon; and Charlotte, North Carolina. Charlotte's efforts are called one of the most dramatic examples of traffic calming for putting arterial roads on "road diets," by reducing the number of travel lanes in each direction.

Ewing and Brown stress throughout the manual that traffic calming is a necessity to help ensure the safety of all roadway users—drivers, pedestrians and bicyclists.

Reid Ewing will be presenting components of the U.S. Traffic Calming Manual at APA's upcoming National Planning Conference in Minneapolis on Sunday, April 26 at 4 p.m. and will be available immediately after the session to sign books. Learn more about APA's National Planning Conference.

The U.S. Traffic Calming Manual is available through APA's for $149.95. The APA member discounted price in $99.95.

ISBN: 978-1-932364-61-3
Hardcover; 240 pp.

Media Copies

Media review copies of the U.S. Traffic Calming Manual are available by contacting Roberta Rewers at or 312-786-6395.

About the authors

Reid Ewing is professor of City and Metropolitan Planning at the University of Utah. He is author of several publications including Growing Cooler: the Evidence on Urban Development and Climate Change, Developing Successful New Communities, and Transportation and Land Use Innovations. He previously wrote the first complete traffic calming design manual for the Delaware Department of Transportation and is co-author of several manuals for other cities.

Steven Brown is a senior principal at Fehr & Peers with more than 20 years of experience in transportation planning and engineering. In addition to his 15 years of consulting experience, Brown was the director of Transportation Planning for the City of Sacramento.  He is a licensed traffic engineer in California and has managed a variety of projects including transportation master plans, parking and circulation studies, bicycle and pedestrian facility plans and intersection/signal designs.


Roberta Rewers, APA, 312-786-6395;