Right Hand Turn Geometry At Urban Arterial Intersections in Edmonton: Guidelines for Application of Different Geometric Treatments For Different Conditions

Right Hand Turn Geometry at Urban Arterial Intersections in Edmonton: Guidelines for Application of Different Geometric Treatments for Different Conditions The City of Edmonton, like many municipalities in Canada, uses the Transportation Association of Canada’s (TAC) Geometric Design Guide for Canadian Roads as the basis for its roadway design standards. Canadian municipalities, while using the TAC guide as a base, have typically developed their own specific geometric standards and typically rely on a single, one-size-fits-all, design standard for all their arterial intersections. The City of Edmonton’s current standard for Arterial/Arterial intersections features right-hand turn geometry that includes a dedicated right-hand turning lane, a three-centered curve with 60m-35m-60m corner radii, a “pork-chop” island separating the right turning lane from the through lanes of the intersecting roadways and no taper on the receiving roadway. The City has, over the years, had concerns over the suitability of a single geometric standard for all situations at arterial intersections. In particular, the City appears to have experienced a higher rear-end collision rate than some other jurisdictions. There have also been concerns about the suitability of the current design standard for situations having high volumes of vulnerable users, or operating conditions that are significantly different from the characteristics implicit in the current design standard. For these reasons, the City commissioned Infrastructure Systems Limited (ISL) to review the current standard and to develop guidelines for use of several different right-hand turn geometric treatments that designers can choose from, to better fit the conditions expected at urban arterial intersections. The guidelines include several different geometric treatments to choose from, as well as criteria for their application. The guide was developed with input from a variety of technical sources as well as from professionals representing the transportation planning, roadway design, transit planning/operations and traffic operations disciplines within Edmonton’s Transportation and Streets Department. The guidelines developed for Edmonton may be of interest to other communities who may wish to consider the proposition that the use of a single intersection design standard may not be the best approach.