More roadway doesn’t mean less congestion

But over the years, researchers have found the opposite holds true. When it comes to increased road capacity, if you build it, the cars will come and keep on coming.

“Our research found that when you add a typical road to a metropolitan area, in a short period of time, you get a proportional increase in total amount of driving,” said Matthew Turner, a professor of economics at Brown University, who co-wrote a study in 2009 that compared added road capacity to the number of miles vehicles travelled in U.S. cities over two decades.

“That result is probably relevant here, too,” said Turner, in an interview with the Star. “I don’t think, on average, it’s going to have much effect on the total amount of traffic in the city.”

Data from the study suggests a fundamental law of road congestion: adding 10 per cent more road capacity to a city increases vehicle miles traveled by 10 per cent.

His research found four reasons for the increase:

• Increased trucking and commercial traffic on the new roads.

• People opted to drive, and for longer.

• People migrated to cities with better roads.

• Diversion of traffic.

A number of other studies published in the UK, Japan and Australia have come to similar conclusions: when road capacity is increased, congestion eventually returns.

A 2014 report from the Victoria Transport Policy Institute, a Victoria-based research organization dedicated to finding transportation solutions, summed it up this way:

“Planners extrapolate traffic growth rates to predict that congestion will reach gridlock unless capacity expands. Adding capacity generates traffic, which leads to renewed congestion with higher traffic volumes. This cycle continues until road capacity expansion costs become unacceptable.”

Does that mean we should never invest in building roads?

Turner said highways are necessary, but cost-benefit analyses are needed to see if the costs of road expansion justify the results. And when the road is built, it should be used it wisely.

“Moving people around is really important. The problem is we are building this thing, but we are not charging people for access, we are giving it away.”

That’s his concern with GTA West, which follows a route parallel to the 407 toll highway, which isn’t typically congested.

“The argument is that there are all these people who could avoid congestion if they were willing to pay for it. But they are not willing to pay for it, so we are going to spend all this public money to simply divert that traffic.”

GTA West highway: Forward thinking or retro mistake?