I have asked them about this - I too think it an error.
I see to that they hint at (daring to) talking about average speed and 85% but they are failing to understand it properly or deliberately.
Speedcheck wrote:
Driver behaviour
Driver behaviour is noticeably better with average speed cameras, with compliance maintained throughout the speed restriction zone. Spot speed cameras often cause 'surfing' or sudden braking at the camera, followed by an increase in speed directly after the camera. This results in a wide distribution of speeds and erratic driver behaviour through the monitored area, promoting flow breakdown and congestion.
In contrast to this, average speed enforcement leads to only small speed variations which creates a smooth flow and safer, more consistent driver behaviour. Compliance is very high, with only a tiny fraction of a percentage of drivers receiving tickets. On a major motorway roadworks scheme, the number of tickets issued weekly is in the hundreds against a typical throughput of over one million vehicles, representing an extremely low violation level.
Traffic volumes change dramatically during any 24 hour period, but average and 85th%ile speeds change very little.
Well I can spend some time pulling this apart !
Of course people comply - who wants some ticket that will after 4 take your license away!
To try to use a forced speed limit area and state that 85% speed vary little - well of course they don't ! It is a totally enforced area with everyone trying to progress at the highest speed allowed, and within judgment ability.
Average camera areas, do cause 'surfing' and the resulting caterpillar after effects too, and this happens every time someone brakes and adjusts their speed by just a few mph, causing many drivers to over and under react, and that adds to the tailgating and near miss incidents within the 'zombie-like' driving styles that happen within these zones.
Speedcheck wrote:
Traffic flow improvements
Traffic flow through a SPECS speed control section improves considerably, resulting in a safer, smoother and more reliable journey. Vehicles can merge and diverge more easily, allowing drivers to enter or leave the carriageway without speeding up or slowing down to find a gap.
The overall result is a conveyor belt type flow, with uniform speeds, little braking, larger headways and fewer collisions. This delivers safer, more reliable journeys for all road users, whilst maximising throughput on roads with a high traffic volume.
They can go on saying this all they like but it is them they are trying to convince the public know that it is not like this. The consistency of bunched and braking traffic creates many difficulties for all those trying to access the Motorway network.
Asking people to drive like robots and remove their responsibility tugs at the very core of good driving abilities. The damage these systems do on drivers and the bad effects that they cause is a sad reflection on how little road safety is being taken by this Government. This sledge hammer to crack a nut shows an appalling lack of attitude and comprehension to this crucially important way to help road safety.