早在古罗马时代,意大利庞培市的一些街道上,人、马、车在一起混行,往往造成交通堵塞。为了解决这个问题,人们把人行道加高,使人行道与车行道分开。然后又在适当的地段,砌起一块块凸出路面的石头——跳石,以此来作为行人通过车行道的标志。行人可以踩着跳石穿过马路,而跳石之 As early as in Roman times, some streets in Pompeii, Italy, where people, horses and cars were mixed together, often caused traffic jams. In order to solve this problem, people increase the sidewalks and make the sidewalks separate from the roadways. Then, again in the appropriate area, a block of rock protruding from the pavement - a stone jump - was used as a sign of pedestrians passing the roadway. Pedestrians can stepping stones to cross the road, while jumping the stone