Lesson learned from the application of intersection safety devices in Edmonton

Area of Science:

• Traffic Safety Engineering
• Transportation Planning
• Public Health

Background:

• Edmonton implemented an intersection safety device (ISD) program in 2009, installing 50 cameras for automated red-light running and speed enforcement.
• ISDs are designed to enforce violations during both red and green phases of traffic signals.

Purpose of the Study:

• To evaluate the safety performance of intersection safety devices (ISDs) in Edmonton, Canada.
• To identify key factors for successful selection of future ISD sites.

Main Methods:

• A before-and-after Empirical Bayes (EB) method was employed to analyze collision data, controlling for regression-to-the-mean and other confounding factors.
• Safety performance functions and yearly calibration factors were developed using data from reference intersections.
• Analysis was conducted at both the overall intersection and individual approach levels.

Main Results:

• Significant reductions were observed in total collisions (12%-25%) and angle collisions (33%-43%).
• No significant reduction in severe collisions was found at the intersection level, but approach-level reductions occurred at high-collision-frequency sites.
• Higher collision frequency at a site correlated with greater collision reduction.

Conclusions:

• Intersection safety devices (ISDs) demonstrate effectiveness in reducing certain types of collisions, particularly at approaches with a history of frequent crashes.
• Factors such as speed limits, separated right-turn lanes, and the number of lanes influence the collision reduction effectiveness of ISDs.
• Site selection criteria, prioritizing locations with higher collision frequencies, can enhance the success of ISD implementation.