The designing of roads and road-furniture (bizarre phrase, but there you go) to discourage cars from speeding. The most common type of traffic calming device is the speed bump, or sleeping policeman (that's has to be a UK only phrase...), but twenty miles an hour signs, speed cameras, road narrowing and huge chevrons painted on roads are also used.
The phrase 'traffic calming', though, is naively hypallactic - and probably consciously so, too, suggesting that it's not the car drivers who are angry, or indeed speeding, but just the cars on their own regardless of the no doubt sober minded, rational driver. Bad cars - naughty cars. The upshot of all this, of course, is an implicit suggestion that car drivers are innocent.
So, 'they' reason, let us calm these aggressive, bad-tempered and strong willed cars with bumps and ramps, automatic fines, traffic lights and roundabouts... Cars may now be calm: the drivers, though, are anything but. It shouldn't be called 'traffic calming' - it should be called 'driver annoying'. Those people who stuck to the speed limit before the measures were taken invariably still drive conscientiously. And those who didn't, warranting the measures in the first place, use speed bumps to take off from, narrow roads to justify their mounting of the pavements, and traffic lights rather like those F1 race-car drivers use the lights system at the beginning of grand prix.
Leading to 'resident annoying'. I wonder how we could calm them?