Comment by jbangert

At least in the east bay, one reason why HOV lanes might run more effectively is that they are also express lanes (limited points at which you can merge in and out). On the other lanes, passing on the right/not passing in the left lanes is ok which slows down merging considerably. Also HOV lanes by definition have twice the (passenger) usage per car, so 2 HOV lanes and 4 regular ones are moving the same amount of people.