1951: The first official zebra crossing starts protecting pedestrians at Slough, just west of London.

Postwar Britain had only 10 percent of its current road traffic, but fatalities were mounting. The typical pedestrian crossing was marked with nothing more than metal studs in the road: easy for pedestrians to see, but difficult for the motorist. By the time a driver felt the bumps under his tires, it was usually too late to stop or slow down.

The government’s Transport Research Laboratory ran visibility experiments on new types of crossings, using model roads at 1/24 scale (a half-inch to the ...