Abstract
Most fatal and serious injury motor vehicle collisions in urban areas occur on arterial roadways. Because the risk of death and serious injury in collisions is minimized at lower speeds, a significant opportunity for improved safety lies in the design and operation of arterial and collector roadways that operate at lower (30 to 40 km/h) and moderate speeds (50 to 60 km/h). Traffic speeds on collector and arterial streets impacts quality of life, and residents often raise concerns to road authorities regarding safety and noise.
Existing Transportation Association of Canada (TAC) publications offer little guidance for designing and operating lower-speed collector and arterial roads. While the Canadian Guide to Traffic Calming (2018) offers some examples of arterial street treatments, it focuses primarily on lower-volume residential streets. The goal of minimizing the potential for serious injury on all urban roads is rapidly growing in importance, and more information is needed about effective practices for streets with higher traffic volumes.
OBJECTIVES
The primary focus of this synthesis will be on 30 to 40 km/h collector and arterial roads, with some inclusions for 50 to 60 km/h roads. This project will:
- Summarize the relationship between vehicle speeds and safety in urban (including suburban) areas, contrasting arterial and collector roads having lower (30 to 40 km/h) operating speeds with moderate operating speeds (i.e. 50 to 60 km/h) in terms of: collision rate, frequency and severity; pedestrian, cyclist and motorist safety; and community livability.
- Assess the possible impacts of using a single target speed (i.e. a consistent design and posted speed) for urban arterial and collector roadways, compared to the conventional use of a design speed that exceeds the intended posted speed by 10 to 20 km/h, as well as the Safe System approach and self-regulating roadways.
- Summarize Canadian and international design and operational practices, including established and emerging/innovative approaches and approaches that are applicable individually or in combination, to promote self-enforcing arterial and collector roadways in urban areas that operate at lower to moderate speeds, separating results by 30 km/h, 40 km/h, and 50 to 60 km/h brackets for both new roads and retrofits. Such practices could include physical applications (e.g. vertical and horizontal deflections, roadway narrowing, pavement markings, surface treatments, etc.) and other approaches (e.g. access restrictions, enforcement, displays, boulevard treatments, etc.)
- Document case studies, including representative schematic illustrations, of recent lower to moderate speed (30 to 50 km/h) urban arterial and collector roadway projects with a focus on treatments used and their impacts on operating speed, safety, community vibrancy, equity and livability.
Key project tasks will include:
- A review of international literature and survey of North American jurisdictions, and other applicable groups, to identify relevant practices and gather case studies that explain applied tools and measured outcomes (like information provided for individual measures in Chapter 3 of the Canadian Guide to Traffic Calming).
- A synthesis of key themes and identification of effective, proven, or promising measures.
In addition to the main synthesis of practice report, the project would also create a memorandum for the attention of TAC committees that identifies gaps and conflicts in existing TAC guidance (notably the Geometric Design Guide for Canadian Roads, and the Manual of Uniform Traffic Control Devices for Canada) and that suggests areas where new, amended or expanded guidance is warranted.
