ViaStrada was commissioned by the Christchurch City Council (CCC) to undertake an investigation into the provision of protected right turns at two of the city’s signalised intersections. This has then led to the development of a draft process for treating right turn problems at traffic signals. The project was presented at the 2008 SNUG (Signals New Zealand User Group) conference in Whangarei.
The first investigation looked into current practices regarding provision of protected and filter right turns and drafted a process for determining the best type of treatment on an intersection-by-intersection basis. The process involved two levels of assessment criteria – safety and network efficiency - these were both assigned draft threshold values. These values were based on previous practices from other localities and were therefore not necessarily the most appropriate values for use in Christchurch.
While specific recommendations were made for the two intersections, another major recommendation that arose from the study was that, as limited resources require prioritisation of intersections for treatment, intersections should not be assessed in isolation but in the context of all the city’s intersections. The consideration of both driver safety and pedestrian safety needed to be made in the prioritisation process.
An extension of the project was therefore commissioned, seeking further investigation into the threshold criteria and how ‘problem’ intersections could be identified and ranked. This would result in an implementation list (in priority order) for the Council to tackle. It was decided that, given the lack of availability of suitable ranking methods, a new method would be developed with a GIS-based selection tool.
This presentation covers the outcomes of the first study and progress so far on the second.
SNUG Workshop, Whangarei