Evidence for Tolls as a 'Surefire' Traffic Congestion Fix

Writing in City Observatory, Joe Cortright suggests that congestion pricing is one of the most effective ways to reduce traffic. He points to an example from Louisville, where traffic on Interstate 65 fell by half after Indiana and Ohio instituted a $1 to $2 toll on a bridge across the Ohio River. 

The two states spent a billion dollars doubling the size of I-65, only to have half as many people use the bridge. That money was wasted. Nothing more clearly illustrates the utter folly of highway expansions. As we’ve pointed out, highway engineers size roadways based on the assumption that the users will pay nothing for each trip. … But ask people to pay, and you’ll get fewer takers.

According to Cortright, this suggests that most drivers don't want to pay to use roads, and will avoid toll roads by taking alternate routes or alternate modes of transport, or not making some trips at all. Even a small toll, such as Louisville's $1 to $2 fee, can have a noticeable impact on congestion and road usage. Meanwhile, highway expansion has been repeatedly shown to induce demand and encourage more driving. While state DOTs have been slow to implement congestion pricing programs, road pricing, Cortright argues, is a "surefire fix for traffic congestion."