Other studies (one in New Jersey, I believe) have shown this as well. HOV lanes increase traffic congestion. This carpool lane thing was always more about social engineering than it was about improving traffic flow.

This is also no shocker:

A report released last year also shows that the most common form of HOV lane, where general and restricted traffic is not separated by a physical barrier, causes a fifty percent increase in accidents.

Car pool lanes with no barriers are nuts, and single-lane carpool lanes are pointless, because one slowpoke can hold up everyone behind. Get rid of them all. Now.