In 2003,officials in Garden Grove,California,a community of 170,000 people wedged amid the suburban sprawl of Orange County,set out to confront a problem that afflicts most every town in America:drivers speeding through school zones.

摘要

Local authorities had tried many tactics to get people to slow down. They replaced old speed limit signs with bright new ones to remind drivers of the 25-mile-an-hour limit during school hours. Police began ticketing speeding motorists during drop-off and pickup times. But these efforts had only limited success, and speeding cars continued to hit bicyclists and pedestrians in the school zones with depressing regularity. So city engineers decided to take another approach. In five Garden Grove school zones, they put up what are known as dynamic speed displays, or driver feedback signs: a speed limit posting coupled with a radar sensor attached to a huge digital readout announcing'TOUR SPEED."