UC research identifies 2 reasons for bus bunching in cities
UC research identifies two key reasons for bus bunching in cities
October 29, 2013
Bus bunching phenomenon in larger cities has been known about for a long time but University of Canterbury (UC) has been researching the reasons for it.
One of these is variability in bus travel time between stops, which is caused by buses being delayed by other traffic in congested conditions, UC transport engineering Professor Alan Nicholson says. He and several UC students have been investigating why bus bunching occurs.
``The other is variability in the time spent at stops, as passengers board and alight and as buses wait to rejoin the traffic stream,” Professor Nicholson says.
A recent report for the New Zealand Transport Agency found that studies in the UK have found that these two sources account for around 75 percent of bus service unreliability.
The report says that its authors were unable to find any New Zealand studies into the contribution of the sources of bus bunching.
Professor Nicholson says recent studies with his students “have found that these two sources make similar contributions to bus service unreliability.”
``Given the finding of the research for the New Zealand Transport Agency, it is likely that our studies are the only ones in New Zealand.
``Our studies involved observations of travel times between stops and times at stops, and using that information to calibrate a simulation model, which can be used to predict when and where bunches form.
``If such observations were done in Wellington and Auckland, the simulation model could be used to estimate the relative importance of the variability in the travel time between stops and the variability in the time at stops.
``Another study in Christchurch has found that two factors, bus service punctuality and the ease of access to a bus service, are significantly more important to bus service users than the bus service fare and level of comfort.
``The variability in travel times between stops can be reduced by giving priority to buses, such as bus lanes along links and increasing the green times for buses approaching signalised intersections.
“The variability of dwell times at stops can be reduced by improving bus design and fare collection methods. It can also be reduced by altering the traffic regulations to give priority to buses rejoining the traffic.
“The research results indicate that giving priority to buses and improving bus design and fare collections methods are of similar high importance if bus bunching is to be reduced,’’ Professor Nicholson says.