Road Markings

[cleedaub1]

Can someone explain the meaning of the occasional
sets of bars painted on the roads ? They seem to consist of 7 wide bars with sets of 5 narrow bars in between. I presume they are something to do with speed measurement.

[heathfield]

They're back-up for the speed cameras. The double flash from the camera when you pass at excessive speed is an indication that the camera has taken two photos of the back of your car. By comparing the time interval elapsed between the two photos and the position of your car relative to the white markings, the police can calculate your speed. In the case of a dispute, they can use this as confirmation that the speed measured by the camera is correct. Or not! To bring a prosocution, the police round my way have to use this confirmation method every time, (much to their disgust, as it takes up so much of their time).