We're about to see a large-scale experiment of demand pricing in a major metropolitan area: Dallas, Texas is implementing this very thing as part of the LBJ Express project.[1] It is scheduled to be fully completed by the end of 2015, but portions of it are already open to traffic, with the demand pricing in place.
It will be interesting to see what happens. For the record, I can see the construction from my office window. I've used the express lanes a couple of times now, and traffic has always been clear on it when I did so. Whether this is due to pricing or simply because it is so new I am not sure. Either way, there was no traffic jams for me (during afternoon rush hour, mind) on the occasions I used them.
It will be interesting to see what happens. For the record, I can see the construction from my office window. I've used the express lanes a couple of times now, and traffic has always been clear on it when I did so. Whether this is due to pricing or simply because it is so new I am not sure. Either way, there was no traffic jams for me (during afternoon rush hour, mind) on the occasions I used them.
[1] http://www.lbjexpress.com/FAQs.asp