Rudman's city: Work out the congestion before counting the cost

By BRIAN RUDMAN

In 1997 consulting firm Ernst and Young estimated the cost of congestion on Auckland roading network as $755 million a year.

Just four years on, the pro-roaders have rounded that figure up to an even $1 billion. Come next year's national election and what's the bet they'll be talking $1.2 billion, or did I hear a $1.5 billion?

Just how they pluck such figures from the ether is anyone's guess when you realise the experts are still trying to define congestion, let alone come to any meaningful conclusions about how much it, whatever it is, costs. Still they are slowly getting there. As far as the meaning of congestion is concerned, anyway.

Last month the board of state highway builders Transit New Zealand agreed to join with the Ministry for the Environment, Transfund, the Auckland Regional Council and other Auckland councils in a trial of a "congestion indicator" for New Zealand roads.

Well, to be honest, they've dropped the title "congestion indicator" after much agonising by the bureaucrats about its accuracy, and have come up instead with something called a "transport travel-time indicator".

But for most of us, the small print is neither here nor there. What it does mean is that for the first time, everyone involved with Auckland roads will be singing from the same songbook when it comes to measuring traffic volumes and travel speeds and the causes of delay.

It's not that some measurement hasn't taken place in the past. But until now, Transit and the ARC and local councils have all had their own methods of measuring such things.

It's been a rather erratic process, done when money allowed, and with the inevitable duplications and incompatibilities of results.

Costs, for example, meant the ARC could venture out only on this task once every two years. The monitoring involved a "floating car" technique, where test cars joined the traffic flow at certain times and recorded the time taken to get from A to B. This was compared with a nominal ideal travel time based on travelling the same distance at the speed limit for that stretch of highway.

The proposed new monitoring trials - in Auckland and Wellington - will begin in the second half of next year and are based on proven Austroads methodology used across the Tasman in Victoria.

The Austroad method surveys around 15 per cent of a city's road network, including all state highways and a cross section of roading types.

Travel times are measured using a calibrated floating car in the traffic stream along each selected route. Each route is driven 15 times in a week (five times each in the morning and evening peaks and five times in off-peak), three times a year, in normal traffic conditions. Possible reasons for delays are also recorded.

The project was initiated by the Ministry for the Environment as part of a project to develop indicators to measure the impact of various pressures on the natural environment.

Traffic delays and congestion were seen as putting pressure on both air and water quality. Its proposal to Transit and the regional councils to rationalise the present ad hoc systems - and share costs - was greeted positively, particularly by Transit, which is now leading the show.

Of course, getting a more accurate and comprehensive picture of comparative travel times - call it congestion or whatever - is only the beginning. It's what we do with the information that is more relevant.

Transit, for example, will no doubt see it as a tool to aid the more accurate calculation of the cost benefits of building more highways to relieve the said congestion.

As for the road lobby, it will regard any evidence of its lorries being stuck on sluggishly moving motorways as a cost that has to be solved by yet more highways.

The ministry, on the other hand, is likely to be more concerned with the effects of the extra diesel fumes being pumped into the environment by the stalled lorries. It would also likely see the road lobby's solution - more roads - as an added cost to the environment.

To me, getting a better picture of road congestion does just that. It illuminates the problem. No more, no less. As for the solution - well, however loud the clamour from the road lobby, that's another matter altogether.