“Congestion is our Friend” – restated

I’ve been arguing since I was a City Councillor that “congestion is our friend.”

In truth, traffic congestion is inevitable given the inability of government to build the road space needed to accommodate the increase in vehicle ownership. (The annual increase in the Vancouver Metro area is the equivalent of a line-up of new cars parked bumper to bumper from West Vancouver almost to Hope.)

Therefore, it’s not a question of whether a region is going to have congestion but where it emerges.

In a sensible world, we would either limit the increase in the number of vehicles to match the road space available – what I’d call the maximum desirable capacity – or charge for the use of the roads in such a way as to limit the worse aspects of congestion.  Of course we do neither.  But Motordom has known since the 1920s that the public will then demand ‘congestion relief’ from the policy makers.

I’ve just come across another more elegant was of stating this thesis in Stephen Ingrouille’s Transport Newsletter #88, in which he quotes Prof. Nicholas Low at the University of Melbourne, who in turn refers to the writing of David Metz:

David Metz … has a different view about bottlenecks. He argues that building roads to relieve bottlenecks transfers congestion to another place downstream, and encourages further traffic build-up over time on the ‘decongested’ stretches of road:

“Many bottlenecks perform a metering function, by reducing the flow at one point to a level that can be sustained in downstream sections of roadway.  Removal of the bottleneck in one location may simply result in transferring the bottleneck to another point downstream. In many cases the newly formed downstream bottleneck may result in worse traffic conditions than maintaining the original bottleneck. Thus, bottlenecks may often play a useful and important function in regulating flows and controlling the level of congestion that occurs on a road network.”

Example of a useful bottleneck: Denman and Georgia, where the Causeway traffic is constrained by the traffic signals and then metered onto the downtown grid.  To remove that meter (or worse, build additional bridge and road capacity into the downtown) would result in congestion in the place you want it least: the West End and Central Business District. 

As Low further argues:

In fact congestion can have a positive function, by inhibiting travel. Congestion is an automatic travel demand management measure, which plays an important role in keeping cities liveable.

Congestion pricing is also a travel demand management measure designed to have identical results in inhibiting travel. It simply monetises and socialises the cost of congestion paid by the motorist. The difference is in that money collected by road pricing is invested socially. If it is invested in infrastructure improvement it will simply increase distance travelled unless there are complementary measures to inhibit travel such as car parking restrictions and land use controls.