Should Car Pool Lanes Require Three-to-a-Car?

Walker cites former Washington State Secretary of Transportation Douglas MacDonald on the beginnings of carpool lanes in Washington:

"Everyone involved at the time believed that later the rule would have to be, and could be, changed to three-to-a-car. Everyone was entirely up-front about this expectation. The trigger would be the growth of traffic in the carpool lanes to the point where access would have to be cut back so that they would still work. Didn't happen. Good luck today with that ticking time bomb for a political revolt."

"If your toll lane is still congested, you're not doing (de)congestion pricing, and your results say nothing about whether it's a good idea," writes Walker.