On New Year’s Day, The Salt Lake Tribune reported that three homeless men were struck and killed trying to cross streets near South Salt Lake City’s new homeless shelter. Various pedestrian safety improvements were mentioned in the article, such as lowering speed limits, painting crosswalks and giving jaywalking tickets.
One pedestrian safety countermeasure, which has proven effective elsewhere, wasn’t mentioned in the article: traffic calming. That is the installation of engineering measures that force traffic to slow down as it goes around traffic circles, goes over raised intersections or squeezes between a center line and curb extensions.
Some of the nation’s most livable and walkable cities have traffic calming programs. Think Seattle, Portland and Austin. Salt Lake City had a very active program until 2003, when the traffic calming program was discontinued due to various social and political issues, mainly related to emergency vehicle response times.
Since then, the former director of the Salt Lake City Transportation Division, Robin Hutcheson, told the city’s Transportation Advisory Board that she received more complaints about speeding traffic than anything else. Yet, she noted that the city had few tools to respond to these complaints.
The current director, Jon Larsen, has confirmed to the TAB that speeding on residential streets is one of the two top sources of complaints, along with parking. So, the problem hasn’t gone away just because the traffic calming program went away.
Which leads us to a study that the Metropolitan Research Center at the University of Utah just completed for Salt Lake City’s Transportation Division. We first identified all the traffic calming measures currently in place around the city. For example, on 2nd Avenue, heading out of downtown, there are two raised crosswalks that act like speed humps, forcing traffic to slow down as they go up and over.
Other common measures are speed tables (flat-topped speed humps), traffic circles and center islands that narrow clearance. All told, students at the U. identified 158 traffic-calming devices throughout the city.
U. students then measured speeds at a sample of the devices, plus upstream and downstream of the devices, using the city’s own pneumatic tube counters placed 10 feet apart. Speeds at, before, and after were compared to speeds on “control” street segments that are not traffic-calmed. The reduction in speed ranged from 5 to 18 mph, with a percentage decrease between 15% to 19%. Overall speeds fell significantly on streets with traffic calming devices on them, and not just at the devices but upstream and downstream. The conclusion of the study: Traffic calming works.
To the extent that traffic calming slows traffic, it also improves safety, the point of this commentary. In the Institute of Transportation Engineer’s “Traffic Calming State-of-the-Practice,” written in the late 1990s, I compared crash rates before and after traffic calming devices were installed in many cities. Significant crash reductions were achieved, particularly with traffic circles placed at intersections where most traffic conflicts occur.
There are now designs that mitigate concerns over emergency response times. The findings of these studies were shared with mayor-elect Erin Mendenhall’s Transportation Transition Team, and their draft report recommends reinstitution of a traffic calming program within the city. It would be a bold step by a mayor who wants to improve the safety, walkability and livability of our great city.
Reid Ewing is a professor of city and metropolitan planning at the University of Utah.