When it comes to solving congestion on main roads, like the A10 and A505, the common sense solution is surely to increase capacity with more lanes, isn’t it?
Campaign for Better Transport and other groups, academics and most transport professionals will argue that this does not solve the problem. It just buys time – typically less than ten years – before congestion reappears. Multiple studies since the 1930s have shown that after an upgrade, much of the growth in traffic is ‘induced’. In other words, people decide to make more journeys or to travel further because there’s a nice fast road available.
Business owners argue this is a good thing: they need a large catchment pool of potential employees so as to attract the best talent to grow their business. Congestion reduces the available catchment area because people tolerate only so much time and stress to commute. Also, with faster roads, businesses can deliver goods more quickly and do more service or sales visits in a day, increasing productivity.
But what about improving train and bus services, cycleways and footways? Isn’t that a good way to increase the labour catchment pool, and reduce traffic and congestion on the roads? “Oh we need to do that too,” respond the politicians, but with rather less conviction than for upgrading roads.
Does conviction matter if they commit to doing both? Well, the business case (the economic justification) for investing in new infrastructure for public and active transport depends on there being a problem to solve. Typically that problem is congestion, delaying journeys and reducing economic productivity.
So, what happens if the road gets upgraded first and congestion goes away (even if only temporarily)? Then the business case for the sustainable stuff evaporates: there’s no longer a problem to solve. Or rather, the remaining problems are not captured adequately in any cost-benefit analysis.
If politicians are serious about making walking, cycling, bus and rail options viable and attractive alternatives to driving, they must invest in that before increasing road capacity. That’s not to say that additional road capacity is never needed, just that sequencing is critical.
This article was first published in the Cambridge Independent on 16 May 2018.