Transit congestion study extended to Tauranga and Christchurch

A study measuring levels of congestion in Auckland and Wellington has been extended to include congestion monitoring in Tauranga and Christchurch.

Transit New Zealand has released the results of travel-time surveys, carried out in March. The surveys have been conducted twice-yearly in Auckland and Wellington since 2002, with the aim of showing congestion trends within the cities.

Transit strategic policy manager Mike Curran said Tauranga and Christchurch had been included because Transit wanted to get a better picture of the congestion that had been detected in those cities.

Travel-time studies using the same methodology were undertaken in Tauranga in 2003, but this is the first time the results have been analysed as part of the wider study.

“Over time, the surveys will allow us to track how congestion levels are changing and determine if new roading, travel demand management and public transport projects are effective in reducing traffic delays. It will also help us identify and monitor congestion ‘hot spots’ along the network,” Mr Curran said.

The congestion indicator (CGI), the performance indicator for the surveys, is calculated using the floating car method developed by Austroads (association of Australian and New Zealand road transport and traffic authorities) and methodology developed by Transit New Zealand and the Ministry for the Environment. A survey vehicle travels with the normal flow of traffic on state highways and major local roads during the morning and afternoon peak periods and in the inter-peak period over five weekdays to gather the necessary data.

Mr Curran said although the study made it possible to compare New Zealand cities with each other and also with Australian cities, the comparison should be treated with caution as the nature of the road network in each city was quite different.

“An example is that the latest survey has found average levels of congestion in Auckland and Christchurch are similar. In Christchurch there is a moderate level of congestion throughout the day, largely reflecting travel on regional arterial routes. In Auckland there are heavy delays in the AM peak, free flowing traffic on the motorways in the inter-peak, and significant delays in the PM peak. As a rough comparison, Auckland travelers may experience a 30-minute to 1-hour delay on a 20-kilometre trip in the AM peak, whereas Christchurch travelers may experience a 10-minute delay.

“The differences reflect the fact that in Auckland some 70 percent of traffic on the strategic network travels on the motorways, where traffic flows quite freely in the inter-peak period. In Christchurch only about 50 percent of traffic travels on state highways and the rest uses urban arterial roads where traffic flows at lower speed and stops more often because of traffic lights, roundabouts and other features of inner-city roads,” Mr Curran said.

“Although comparisons between different cities can be made, the real benefit of the study is that it will provide a long-term picture of how congestion within a city changes over time,” Mr Curran said.

The survey in Auckland was partly funded by the Auckland Regional Council, the Tauranga survey was carried out in conjunction with the Tauranga City Council and Western Bay of Plenty District Council, while the Christchurch City Council and Environment Canterbury helped fund the study in Christchurch.

http://www.transit.govt.nz

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