An interesting traffic experiment continues apace in the Kentucky city. The earliest part of the experiment showed that adding tolls reduced traffic. And now, through this data collection, the city is finding that “it isn’t just that traffic has shifted to the ‘free’ alternative. It’s that, with tolling in place, apparently many other trips just simply evaporated.”
The tendency of traffic to disappear when there’s a toll is an indication that people have much more flexibility about when, where, and how much they travel than is usually contemplated in policy discussions or travel demand models. The mental model that says traffic levels are some inexorable natural force like the tides, which must be accommodated or else, is just wrong.