It always amuses me when people say it is ridiculous that the speed limits are in place when there are no workmen actually working at any given time.
I attended an RTC on the M4 in the early hours of one Sunday morning in the section where there is road widening.
A stretched limousine driver had lost concentration whilst attempting to "put music on a particular radio station for the passengers" and suddenly realized that he was about to hit the rear of a car in front doing the legal 50 mph, he was doing around 80.
He slammed on his brakes, but unfortunately for him, his brakes were faulty and it pulled him across the line of cones into the contraflow where he hit a car coming in the opposite direction, also speeding. The result was two seriously injured in the other car, a limousine full of drunken girls with cuts and bruises (probably being saved from serious injury by being pizzed) and him getting banned for Dangerous driving and unroadworthy car.
(guess which patients I ended up treating?

So do the "temporary speed limits" matter when the roadworks is not manned?
I think so!