Advocates of London-style congestion pricing in New York ran into two roadblocks late last year.

One was politics. Mayor Michael Bloomberg surprised them by declaring after his November re-election that road pricing was not part of his second-term agenda. The other obstacle was the three-day strike by transit workers just before Christmas, which vividly demonstrated the problems that arise when limits are placed on traffic flowing into Manhattan. Strict rules imposed during the strike meant deliveries of everything from medical equipment to fresh flowers were delayed. And frustrating bottlenecks were created when the restrictions were lifted.