Are speeding tickets necessary?

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Tom Vanderbilt writes that the mere act of pulling people over could be enough to reduce traffic violations — without actually issuing fines:

[T]here is evidence that what often matters in reducing traffic violations is not punitive action per se, but simply the process of being pulled over and receiving the warning. This imparts the idea that the driver has violated some community norm, and reminds him (and other drivers who pass by) that there are police looking after those norms.

The effects can be dramatic and long-lasting. Take the example of a study in Miami Beach: after a two-week period in which drivers received police warnings for violating pedestrian right-of-way in crosswalks, the violation rate dropped drastically — and a year later, without enforcement, it was still down.

One worry is that a city that didn’t hand out tickets would lose revenue. Vanderbilt counters that figuring out ways to reduce traffic accidents is a much more efficient way to lower costs.