When they first brought these things to the DC area (the 495 express lanes in Virginia), the toll was capped at $10. It didn't take long before they were routinely hitting the cap and seeing traffic at a standstill in the "express" lanes, so they ditched it.

Since the whole point is to reduce congestion, implementing a cap (price ceiling) is absurd. When a price ceiling is set, a shortage occurs. In the case of road usage pricing, a shortage means a shortage of capacity.

In other words, you end up with traffic congestion and tolls, the worst of both worlds.

I read a similar thing about Houston where it's capped at $8 and has little effect on reducing congestion. The first course of action should be to remove the price cap. (And expand the number of paid lanes, which would decrease the cost paid by drivers by spreading it out over more lanes.)

You can't have your cake and expect it to eat it too by imposing usage pricing with price caps.

Economics 101: price ceilings cause shortages.

There's a proposal for an express lane on US 101 in California, and when they hit the cap the lane will become "HOV only".

I wonder if congestion will ever get so bad that they'll have to start adding tolls for HOV vehicles too.

Interesting system. That's effectively a sudden massive increase in price to whatever the fine is for an HOV violation. But the fact that it's a fine rather than a traditional price will change the way people think about it.

It would be fascinating to see a graph of historical price information for the 495 express lane tolls, even over just the last few days/weeks. A cursory examination of Google results didn't yield anything unfortunately. Maybe a fun weekend project?

It looks like the data is available for scraping:

https://www.expresslanes.com/historic-rates

You "just" have to pull it all in and present it nicely.

That expresslanes URL is for I-495. The I-66 historical data is here: https://vai66tolls.com/ And I too would love to see that data in a more convenient form, via an API, etc.