Do Speed Cameras work?

Do Speed Cameras work? This was the question posed this morning on BBC's Breakfast show and the answer is - yes, or possibly no. One area removed them and found no change in incidents, one area added them and noticed a reduction.

To my mind the problem is once again a focus on the event and not the cause; rather than stopping vehicles speeding - why are they speeding? To this end I propose a hypothesis tentatively titled "Compensation of speed".

"Compensation of speed" - Any vehicle when forced to slow down for whatever reason will automatically compensate for this as soon as they are able to do so.

Unfortunately compensate could mean over-compensate. Why does traffic blast up Dunley Road and Vale Road - because they've just been forced through the town. Lion Hill - through Mitton Street. Sutton Park Road and Sutton Road - because they've been stuck at the traffic lights. In all theses examples traffic is slowed down and then presented with the opportunity to speed up on these nice straight wide roads, an opportunity they accept.

The current tactic is to keep traffic at a slow rate, but what if it were possible to prevent the slow-down in the first place?

As I say hypothesis, but I'd be interested in seeing data from incident hotspots and examining the traffic flow of roads feeding it.