Building bigger roads won’t make driving nicer. It will make traffic worse. That may seem counterintuitive. It’s also one of the most studied assertions of the last few decades in transport planning. A report from the University of Berkeley shows that for every 1% of extra highway capacity added, traffic volumes increase 0.9% in the longer term. When Houston, Texas expanded the Katy Freeway to 26 lanes at a cost of $2.9 billion, commute times went up. But you don’t have to look to the southern tip of a failed state for examples. Traffic volumes around the $1.4 billion Waterview Tunnel are roughly back to where they were before its construction.
This makes sense when you think about it for more than two seconds. When Apple releases new iPhones, people buy phones. When Hayden Donnell releases episodes of Get It To Te Papa, people watch Get It To Te Papa*. When governments build flash new roads, people drive. Even if the resulting traffic doesn’t clog up the motorways in question, it tends to funnel into suburban streets or smaller highways. The best we can hope for is to shift the bottleneck.
Going all in on roads in an age of climate change impacts scares me (possibly in a very clear way, living in Hawkes Bay and through Gabrielle). Roads, especially where they are bridged over rivers or over hilly terrain, are not resilient transport links.
Making them the only thing getting any investment means alternatives like rail (at the same risk, but slightly more resilient due to needing to cut less of a hillside away and more likely to have tunneled through the worst) and coastal shipping aren’t going to get a look in. As with most things Nactional Fist are doing, it’ll feel ok for a few years, but 10, 15, 20 years from now I fear we will look back on a huge missed opportunity to do things differently.