Abstract Manager

The City of Surrey adopted its Vision Zero Safe Mobility Plan in 2019, formalizing its commitment to road safety.  However, prior efforts and the implementation of typical Vision Zero measures had resulted in the annual rate of police-attended killed and seriously injured (KSI) collisions plateauing even before the plan's adoption, and despite substantial population growth and development.

However, trying to understand these data on a more in-depth level, to ensure confidence in the results and aid in planning for the future, has led Surrey away from past practices of a study of Citywide averages and subjective methods.  For instance, visual representations of the intensity of incidents in a location, while offering a valuable snapshot of event frequency, lack the depth required to discern the true significance of these occurrences.  Recognizing this limitation, our project sought to go beyond traditional deterministic analysis by integrating advanced statistical techniques and spatial analytics into the analysis framework, to assess the significance of the City’s interventions.

This project explored different analyses to measure the effectiveness of the countermeasures, including hotspot analysis, emerging hotspot analysis, trend analysis, and change detection.  Hotspot analysis and emerging hotspot analysis allow us to delve deeper into the data and find the locations of statistical significance with a certain confidence overall and over time respectively, while trend analysis is interpreting an increase or decline over time.  Change detection gives us insights to when the shift has happened and, if applicable, link it to a countermeasure or design change. 

In conclusion, our approach centers on spatial-temporal analysis to identify collision patterns and trends over time.  By utilizing spatial statistics, our study transcends deterministic analysis and anecdotal visualizations.  The methodology has the potential to change how we measure success; instead of merely acknowledging high-frequency areas, it delves into the contexts and interventions with the greatest promise for risk mitigation.