Building more roads is not 21st century thinking

Sydney Morning Herald: Building more roads is not 21st century thinking January 12, 2015 Jacob Saulwick Transport Reporter

The trend is clear and it’s been that way for a while. The question is what, if anything, to do about it?

Every year the average person in big cities, including Sydney and Melbourne, drives less than they used to the year before.

In Melbourne, the average person drives about 6 per cent less than they did a decade ago.

And Sydney residents in 2013 drove an average 2.4 per cent fewer kilometres than they did in 2003, according to figures derived from a Bureau of Infrastructure, Transport and Regional Economics report released just before Christmas.

There are a number of explanations for the trend, many of them overlapping. But one convincing account comes in the theory of the travel-time budget.

In numerous studies, international academics have demonstrated that there is a certain amount of time people are willing to spend travelling each day. That is their travel-time budget.

People may exceed their budget in the short-term.

But over a longer period, if they have to spend more than about 80 minutes travelling, they will make changes to their lives to fall back within their travel-time budget.

And if people start going under their travel-time budget – Seventy Minutes Plus or Minus Ten is the name of a recent review of the literature in this area by Asif Ahmed and Peter Stopher of the University of Sydney – they will probably find other trips on which to spend their travel time.

This seems to pass the commonsense test.

If, suddenly, your work commute drops to 10 minutes because you start living near your office, you might then be more likely to drive, cycle or walk to a better set of shops in the evening.

Now when you combine this concept of a travel time budget – we all have a limited number of minutes we are prepared to spend travelling – with the demonstrably worse congestion on our roads, an explanation for the drop in driving kilometres emerges.

“If the budget of travel time is the same and your travel time is mainly going up because of congestion, you are not able to cover longer distances because you don’t want to spend much more time in your car,” says Michiel Bliemer, Professor in Transport at the University of Sydney.

“That maybe explains this trend: if your vehicle is not getting faster on the road, you cannot cover longer distances,” he says.

So what are the implications of this?

One response would be to build more roads.

The clearest formulation I have seen of the rationale behind this approach is in the 2012 NSW State Infrastructure Strategy, which continues to form much of the basis for the state’s policies.

The document says new roads are needed merely to allow a growing population to be able to spend their travel-time budget in productive ways.

“New roads are not primarily required to increase journey speeds for existing users in peak hours,” the report says. “Rather, new roads provide the capacity needed for a growing population and economy.”

Accordingly, Infrastructure NSW recommended a large expansion in Sydney’s motorway network.

But if you accept the theory of the travel-time budget, this approach also implies there will be a never-ending need for more motorways.

Even if those new roads suddenly allow us to all drive a lot further, and thus undertake more economic activity, people will just spend their travel-time budgets on these new roads. The new roads in turn will become full, requiring still more roads.

“Trying to reduce congestion by expanding capacity may succeed in the short term, but will attract additional travel in the long term until congestion reaches or exceeds its prior level,” is how Ahmed and Stopher put it.

But the road builders don’t have all the arguments, of course.

Plenty would make a virtue of the decline in car use in our major cities, and argue that it is also a rational response to the changing nature of urban life.

More people work in offices and shops in densely populated areas – there is not enough space for everybody to drive and park.

Higher rates of public-transport use across the country in major cities reflect the way in which people are responding to this lack of space.

Bliemer is one who thinks the time has come to more aggressively support this growth in public transport, and get off the never-ending cycle of motorway building.

“Maybe we should not build more roads and just invest more in public transport, and then we don’t have that problem in the future maybe,” he says of the constant requirement to upgrade road systems.

Peter Newman, Professor at Curtin University in Western Australia and a former board member of federal advisory body Infrastructure Australia, is also of this view.

“What I found on the board … was that all the rail projects were actually far better in terms of benefit-cost ratios than the road projects,” Newman says.

“That’s why WestConnex [in Sydney] and the East-West Link in Melbourne, they wouldn’t even give them to us to look at, because they knew the benefit-cost ratios were pathetic,” he says.

“This is not 21st century thinking, and it isn’t supported by any of the data.”

The trend might be clear. But we don’t seem to have worked out what to do about it.

Ross Gittins is on leave.

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