Rationing Can Backfire
研究发现墨西哥城限制每辆车每周停驶一天的禁令反而增加了总行驶量，因为家庭购买额外车辆并增加使用，导致福利损失和预期目标落空。
A ban restricting each car from on a specified weekday is found to have increased total in Mexico City. Because of the ban, cars effectively represent driving permits, and some households have bought an additional car and increased their driving. Greater use of old cars, congestion effects, and increased weekend may also have contributed to the disappointing results. The ban has high welfare costs and does not deliver the intended benefits of reduced driving—quite the contrary. The experience provides an interesting lesson in applied welfare economics. Theory indicates that this is a costly way of reducing traffic and pollution. But the finding that the strategy is counterproductive could be made only with applied quantitative analysis.