Five years ago this month, a northbound carpool lane opened on the 405 freeway, between the 10 and 101 freeways, widening 10 miles of the interstate. It took half a decade to construct and cost more than $1 billion.
Since then, average northbound drive times through the Sepulveda Pass have increased at all hours of the day, according to data from traffic analyst Inrix.
With more drivers on the road, it’s not surprising that delays have increased along the 405 since the carpool lane opened, but the numbers from Inrix highlight the potential for widening projects like the Sepulveda Pass project to deliver diminishing returns.
How many times does this have to happen before policymakers begin to understand it? This is the classic example of induced demand: if you build more freeway, then the initial lightening of traffic will put more people into their cars, and you will be right back where you started. And in fact it could be worse, because people will potentially buy more cars, leading to greater gridlock. And of course, millions more tons of carbon emissions, as the story makes clear.
A couple of important caveats here:
First, the 405 widening project was part of the American Reinvestment and Recovery Act, better known as the 2009 stimulus package, so it was a jobs package as much as a congestion relief package. As Keynes noted in his classic The General Theory of Employment, Interest, and Money:
If the Treasury were to fill old bottles with banknotes, bury them at suitable depths in disused coalmines which are then filled up to the surface with town rubbish, and leave it to private enterprise on well-tried principles of laissez-faire to dig the notes up again (the right to do so being obtained, of course, by tendering for leases of the note-bearing territory), there need be no more unemployment and, with the help of the repercussions, the real income of the community, and its capital wealth also, would probably become a good deal greater than it actually is. It would, indeed, be more sensible to build houses and the like; but if there are political and practical difficulties in the way of this, the above would be better than nothing.
The 405 widening project was pretty much Keynes in action. And it worked. Which leads me to the next point:
Second, since the measurements here are taken from 2009, the trough of the Great Recession, it is to be expected that traffic will increase as commerce does. So perhaps the greater congestion isn’t surprising.
But the general point still holds: you cannot build your way out of traffic congestion. Instead, you have to do other things, like congestion pricing (which can be refunded to taxpayers on the basis of need) and yes, build more transit. As the dean of American transportation writers, Anthony Downs, advised more than a quarter of a century ago:
My advice to American drivers stuck in peak-hour traffic is not merely get politically involved but also learn to enjoy congestion. Get a comfortable air-conditioned car with a stereo radio, a tape player, a telephone, perhaps a fax machine, and commute with someone who is really attractive. Then regard the moments spent stuck in traffic simply as an addition to leisure time.
The fact that one still needs to use a quote referring to a “tape player” shows how long we have known this, and how long we have been ignoring it.
It will be interesting to see if self-driving cars, if they ever become operational, will change things. But one things we know won’t change things: pouring more concrete,