Merry Christmas Everybody!
We’re just back from having lunch with Mum and Dad, however on the way up, as is often the way over holiday weekends there were a couple of places on the trip where the motorway digital display signs had just been left for no apparent reason. Heading towards London on the M4, between Reading and Maidenhead the signs showed 60, then several 40’s, before an ‘End’ just before Maidenhead. Needless to say there was no problem at all. (It looked like the signs were still incorrectly set when we headed home.)
What was slightly more concerning was there was a repeat on the M25 between the M4 and M40. Firstly a 60, then a series of 40’s, again for no apparent reason. The big problem with the signs on that part of the M25 is that they are part of the variable speed limit system. For those who aren’t aware, the western part of the M25 has regular overhead gantries displaying the speed limit, which changes according to the prevailing traffic conditions (under the control of an operator – hence why they sometimes get left on). The key difference between these and the signs elsewhere on the motorway network is that the speed is enforced by speed cameras on the rear of some of the signs. It is actually possible to spot the live signs, as the system is entirely digital, and each live gantry has a short aerial on the end to transmit the snapshot of you driving past. It just so happened today that the last gantry showing 40 was live, and people could see the derestriction sign on the next gantry. I wonder how many people are going to get caught out?
It does highlight a pertinent point. The whole point of the signs is to allow the traffic flow to be managed, however because almost everybody has come across a situation where the signs have been left on, people tend to ignore them, so they quickly become ineffective. To address this, we now have speed cameras on the back, but we still get the signs being left on. The difference this time is that people end up slamming on their brakes when they realise that there is a camera!