Price Signals

It's been a long time since I read The Research, but the problem with variable tolling with posted price changes is that the price communicates (correctly or not) to drivers just how hellish the alternative is. A low toll suggests that you don't really "need" to pay the toll, while a high toll suggests that you'd better pay it or you're going to be on a parking lot for awhile.

With phone traffic apps, people have other quick ways of getting information. Still, over some range, raising the price might actually increase the number of drivers.

Metro's algorithm modifies the per-mile toll as frequently as every five minutes, based on how many cars are using the lanes. Tolls range from 25 cents to $1.40 a mile, for a maximum one-way price of $15.40 along the 11-mile route. As cars enter the lanes, the price at that moment appears on overhead digital signs. In theory, a higher toll will discourage some drivers from using the lanes, freeing up space and speeds for the remaining users.

But that isn't always happening. Paying the maximum charge along some miles of the route is "almost a guarantee" during the 5 a.m.-to-9 a.m. rush hour, said Kathleen McCune, Metro's congestion reduction director. Even then, toll-lane traffic stays thick.