Research to help reduce traffic jam disruption
12 March 2013
The impacts of traffic snarl-ups in New Zealand's major cities could soon be greatly reduced, thanks to pioneering research by University of Canterbury transport engineering
The impacts of traffic snarl-ups in New Zealand’s major cities could soon be greatly reduced, thanks to pioneering research by University of Canterbury transport engineering experts.
The research is investigating how the movement of vehicles on New Zealand’s city roads can be more efficiently managed after accidents and breakdowns.
UC senior transport engineering lecturer Dr Glen Koorey is working on the project with Professor Alan Nicholson, PhD student Susan McMillan and traffic modelling specialists Aurecon. UC received a $170,000 grant from the New Zealand Transport Agency to research the issue.
Dr Koorey said the aim of the project was to improve the reliability of New Zealand’s existing transport network by finding ways to minimise disruption to traffic caused by unplanned incidents. New technology such as Intelligent Transport Systems (ITS) and better incident management plans were helping.
"Traditionally, management of our major urban arterials and motorways is fairly ad hoc, relying on manual intervention and educated guesswork to try to redirect or re-prioritise traffic if something unexpected occurs on the network. Sometimes, in trying to fix a traffic blockage due to some incident, the treatment may actually result in worse problems over the network as a whole.
"Our current research has used computer simulation models, together with collected field data, to reproduce the effects that a range of incidents will have on the network. The model simulates both the road network and the traffic signal system, which automatically adjusts traffic signal timings at our intersections, based on traffic demand.
"We took a section of Auckland's North Shore traffic network, replicated it in a model, and then applied some actual and hypothetical incidents to it. Then we tried some different treatment strategies to see whether they improved the situation better than the automatic default traffic signal system adjustments,’’ Dr Koorey said.
Different techniques included variable message signs to inform and divert traffic, re-prioritising traffic signals along a particular route and opening up an extra temporary motorway lane on the shoulder.
The latest modelling results show that applying different management techniques to a network following an incident can see big reductions in both average travel times and the average variation of travel times, which was especially important.
"People are often more concerned about the variability of their trip times rather than the absolute duration. They can plan for a longer journey time if they know about it. It is the uncertainty that causes problems.
"However, these solutions may only work in some situations. If you are already at peak hour congestion with little spare capacity, then no amount of tweaking will improve an unexpected incident situation but there is the potential in the shoulder periods of peak time to make considerable gains.’’
Dr Koorey expects to see their findings used by the urban traffic management centres in New Zealand’s main cities in the future.
"We’ve had a lot of interest in our research from within the transport industry, particularly in Auckland, because of the possible benefits that could come out of it in terms of network management and improved reliability for motorists,’’ he said.
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