Traffic police in China have come up with a cost effective way of slowing down speeding motorists - with a cardboard cut-out of a squad car.The cut-outs, which look like police vehicles from behind, are being used as a traffic calming technique in eastern China's Jiangsu Province.One motorist, Liu Yuan, said: "I spotted what I thought was a police vehicle parked on the hard shoulder so I hit the brakes."It when I went past it, I was stunned to see that it was just a thin piece of board painted to look like a cop car."It was so realistic. It even had a solar panel to power a flashing light to make it look even more realistic at night."A spokesman for the local police, in Wuxi City, confirmed that cardboard cut-outs of police vehicles were being used to slow traffic.