Arterial Traffic Calming

Between 2008 and 2010 in Canada, 25% of road users killed and 19% of victims seriously injured incurred their injuries in crashes where speed was cited as a contributing factor.

Traffic calming is a combination of primarily physical measures intended to reduce the negative effects of motor vehicle use, alter driver behaviour, and improve conditions for non-motorized street users. (Transportation Association of Canada, 1998). The overriding purpose of traffic calming is to restore streets to their intended function by reducing speeds, discouraging excessive through traffic, and minimizing conflicts among road users. Traffic calming measures typically include vertical and horizontal deflections in the road surface, as well as road obstructions and traffic regulations.

Skene cited an example of arterial traffic calming in Victoria, B.C on a high crash corridor just outside the downtown core, in which the city converted a four lane section of arterial road to one lane in either direction, added all day street parking and pedestrian refuges, and calmed or made the corridor safer through signal timing adjustments and re-striping the travel lanes. This resulted in a reduction in vehicle speeds (9.5%), better managed traffic, and a significant crash reduction (46.9%).

An arterial gateway is used in speed transition zones to identify the transition from a rural to an urban environment. Its primary function is a reduction in speed and improved safety. Skene cited a pilot project that involved the implementation of an arterial gateway along a highway that ran through the town of Smithers, B.C. The gateways were intended to include narrowing visual clues, special signage (such as "Welcome to Smithers"), and landscaping special paint markings. The estimated effectiveness of the changes was not provided.

The Federal Highway Administration cited the improvements made to a principal arterial in the State of Washington that carried 25 000 vehicles a day. Prior to the implementation of traffic calming measures, it had two travel lanes in each direction with a middle two-way-left-turn lane, and more than 160 collisions were reported over a three year period on a road section that was less than a mile long. The roadway was improved by building curbs, gutters, sidewalks, bike lanes, street lights, pedestrian crosswalks, landscaped medians, and planter strips. The two-way-left turn lane was replaced by a landscaped median and provided U-turn capabilities at intersections for passenger vehicles only. The road improvements resulted in reduced travel speeds and a 70% reduction in traffic collisions.

Scope of the Problem

• Transport Canada (2008-2010). National Collision Database. Retrieved from http://www.tc.gc.ca/eng/roadsafety/resources-researchstats-menu-847.htm.
• Transportation Association of Canada (1998), Canadian Guide to Neighbourhood Traffic Calming. Ottawa: TAC.

Evidence

• Skene, M. Traffic Calming on Arterial Roadways? Retrieved from http://www.ite.org/traffic/documents/AHA99B08.pdf.
• Federal Highway Administration (2005). Arterial Traffic Calming Success Story: Bridgeport Way W. U.S. Department of Transportation. Retrieved from http://contextsensitivesolutions.org/content/reading/arterial-traffic/?