In urban areas, the majority of fatal and serious injury motor vehicle collisions occur on arterial roadways. Recognizing the potential for improved safety at lower speeds, the Transportation Association of Canada (TAC) has undertaken a project to address the design and operation of arterial and collector roads that operate at low to moderate speeds (30 to 50 km/h). This initiative aims to provide practitioners with the necessary guidance to minimize the potential for serious injuries and enhance community livability.
Existing technical guidance provided by TAC focuses primarily on residential streets, leaving a significant gap when it comes to designing arterial roads to prioritize safety. TAC and the Canadian Institute of Transportation Engineers Canadian Guide to Traffic Calming (2018) does offer some examples of arterial street treatments but falls short in fully addressing these higher-volume roadways. To address this growing concern, TAC's project seeks to provide more detailed design guidance for arterial and collector roadways, considering both collision frequency and severity, as well as pedestrian, cyclist, and motorist safety.
The project will delve into the relationship between vehicle speeds and safety in urban areas. By contrasting arterial and collector roads with low to moderate operating speeds (30 to 50 km/h) against higher-speed roads, the study will analyze this relationship in terms of collision frequency and severity, pedestrian, cyclist, and motorist safety, and influence of operating speed on community livability.
Traditionally, urban arterial and collector roadways have been designed with a speed standard that exceeds the intended operating speed by 10 to 20 km/h. This project will assess the potential impacts of using a single target speed, compared to the conventional approach. By reconsidering the design speed standards, the project aims to improve safety outcomes and optimize the effectiveness of traffic calming measures.
The project will summarize Canadian and international design and operation practices that support low-to-medium operating speeds on urban arterial and collector roadways. It will explore various geometric design features such as curvature, visual friction, medians, left-turn calming, and roundabouts, among others. Additionally, the study will assess the potential safety impacts of introducing physical roadside measures like street parking, trees, furniture, and bollards. Other considerations include corridor coordination, signal timing modifications, signal spacing, and automated speed enforcement.
To provide practical insights, the project will document case studies of recent urban arterial and collector roadway projects that have achieved low-to-medium speeds (30 to 50 km/h). Examples such as Ottawa's Elgin Street and Toronto's Port Lands Road network will be examined in terms of the treatments used and their impacts on operating speed, safety, community vibrancy, and livability. These case studies will offer valuable lessons and highlight successful strategies for implementation.
The project encompasses several key tasks, including a survey of Canadian and American jurisdictions to identify relevant practices and gather case studies. A comprehensive review of literature on available tools and their potential effectiveness will be conducted, similar to the approach taken in TAC and ITE Canada’s Canadian Guide to Traffic Calming. Through these tasks, key themes will be synthesized, and promising measures will be identified.
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