An Animated Argument For Congestion Pricing
In 1951, Milton Friedman coauthored a paper on road pricing. It would be a mere footnote in both Friedman’s career and in the intellectual history of road pricing, if not for one sci-fi flourish: The authors propose painting radioactive material alongside expressways, so that road operators can charge drivers using car-mounted geiger counters. Obviously, this suggestion was never heeded, but it says something about the economics profession’s hunger for pricing roads that a future Nobel laureate would set his imagination to Bradbury mode to advance the cause. Ken Livingstone, mayor of London, later credited Friedman with inspiring London’s pathbreaking congestion charge.
Since the 1920′s, economists have nurtured an elaborate theory of road pricing rules, but until recently, it has never been very practical to price roads on a per-mile, time-variable basis. The time and money wasted collecting the money weren’t worth it. The digital revolution, however, has recently given us E-ZPass, online bill-pay, database computing, and even plate-reading cameras. Putting a price on roads that varies according to demand, or “congestion pricing,” is suddenly practical.
To economists, the problem with congestion is that some drivers are harming other people to get something they don’t even need. It’s like if you were slightly hungry but you ate a starving child’s Thanksgiving dinner. For a congested road, an extra car harms travelers already on the road by slowing down their cars and buses. I’ve illustrated this time cost with the following cartoon:
Of course, it’s all right to consume other people’s time if your benefit from driving is sufficiently large. We just want to make sure your trip is “worth it,” and the way our society makes this determination in the division of other resources is by charging money.








