Why do people drive so much? Because we pay them to drive.

It’s no secret that we subsidize driving to a degree that’s vastly disproportionate to other kinds of transportation. Joe Cortright has a great piece in City Observatory that discusses this.

The biggest problem with transportation is we don’t price road use correctly, to reflect back to road users the costs that their decisions impose on society and everyone else traveling. In essence, we have daily urban traffic jams for the same reason Ben and Jerry have long lines on their annual Free Cone Day: when you don’t price something valuable, it gets rationed by queuing and patience. What’s worse is a lot of people who are driving on many roads at the rush hour is essentially because we are paying them to do so.

This issue is one reason why many pro-biking and pro-walking arguments fall flat. No matter how cheap it is to bike or walk, our society is offering you an extraordinary wealth of car infrastructure to use for free. You’d be crazy not to take that deal! The cost of your gas, loan repayments, repairs, and insurance is all offset by the money we collectively spend just to maintain the roads you use.

Cortright goes on:

When we ask road users to pay even a modest fraction of the cost of providing that expensive peak hour road capacity, many of them tell us, by voting with their feet (or their tires), that they simply don’t value the roadway enough to pay for even a tiny fraction of its cost.

A common argument for why we need to keep paying for car infrastructure it that people need to use it. This is a true statement, albeit an unfortunate reality. The problem with this argument is that we’re also subsidizing the people who only use it because it’s “free” for them to do so. This is one reason why adding lanes rarely reduces congestion. Drivers quickly take advantage of their new “free” space.

Cortright also reveals an aspect of this issue that was new to me. Data shows that there’s only a small threshold between congested and free-flowing traffic.

One of the fascinating, and least widely understood aspects of the science of traffic jams is that it takes only a small reduction in traffic levels to keep roads flowing freely. As long as traffic levels stay below a tipping point where the road becomes saturated and loses capacity, the road works well. Adding (or subtracting) just a few cars when traffic is at this tipping point makes a huge difference both in travel times and how many cars a road can carry.

This data on traffic tipping points provides an insight into a solution. We don’t need a drastic traffic reduction to fix congestion, only a slight one. Perhaps this data can make proposed reductions seem reasonable to skeptics.

For decades, our public policy (and public opinion) has prioritized getting as many people driving cars as possible. This agenda’s current success has only revealed that it wasn’t actually the ideal goal we had assumed it was. Any long-term transportation planning now needs to look beyond cars as the endgame. One good way to start is by ending driving subsidization.