The Challenge

There are 455 of intersections in the Auckland region that meet the High Risk Intersections Guide definition of “high risk”.  Auckland Transport (AT) does not currently have the resources to investigate the crash risk for all identified high risk intersections. AT determined that to improve the safety of these intersections, they would heed an effective way to identify which would benefit from further investigation. They enlisted Abley to develop an automated process of reviewing crash records to identify common crash factors.

The Solution

The Abley team developed an automated process using GIS to identify which crash factors were over-represented in accidents at high risk intersections.

The team established thresholds for non movement and crash movement factors to determine at which point a crash factor was considered over represented at an intersection. Thresholds were developed for each intersection type based on speed environment, traffic control type and number of approaches e.g. urban signalised T-intersection.

 The Outcome

The crash factor commonality results were displayed in a web-map which allows Auckland Transport staff to identify which intersections will likely benefit from further investigation. The web-map approach enables the results of an area to be mapped so a themed programme of works (e.g. increased skid resistance to prevent loss of control crashes) can be developed an area or corridor.