It looks to me as if they wasted their money here, either that or they have not learned to manage it yet.
If the traffic is unable to travel at the posted speed then the system isn't working and may as well not be there.
It should extend further north and slow traffic more as it approaches junction 10/10A so Jn 8/9 is able to cope with the traffic volumes arriving.
Today we have (apart from the roadworks at J10 a gantry set at 40 just before the M54 and then straight back to 60, at Jn 9 we have stationary traffic and stop start through to the M5 Junction . . .
Now if the speed from J10 down was lower the traffic would flow better to the M5, but when will they learn?
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As a profeshunal driver I go through at least a couple of stretches of managed motorway every day. By and large they work, as most drivers stick to the posted limits and don't continually keep changing lanes. The problems arise when some drivers speed up and slow down repeatedly, and jostle for a better position in the queue.
>> If traffic is unable to travel at the posted speed then the system isn't working and may as well not be there
40 is the lowest speed the gantries display. Certain stretches of road clog up at certain times of day regardless. It's unrealistic to expect the M6 at j10a-j8 to flow at 40mph+ ceaselessy 24/7.
>> Today we have a gantry set at 40 and then straight back to 60, [then] at Jn 9 we have stationary traffic
>> and stop start through to the M5
...when you came past there. If they set all the gantries to 40 too soon then the traffic before j10a will come to a halt. It's quite likely (almost certain in fact) that the M5 bottleneck was down to drivers changing lanes for the junction far too late, and baulking other vehicles in the process.
There's a reason lane splits are signposted on gantries 1 mile in advance, and it's not so drivers can move into the correct lane after the 100 yard marker.
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...down to drivers changing lanes for the junction far too late, and baulking other vehicles in the process.
Spot on, Dave - and not just there. That's the paradox that all traffic management measures come up against: if everyone behaves sensibly, holds back and leaves enough space to keep the traffic flow elastic, it works and one nervous brake dabber doesn't halt the whole procession.
Trouble is, one driver then sees a gap and spots an opportunity to get ahead. Another sees him and follows suit. Some others see drivers 'jumping the queue' and close up to the car in front to stop them. Then one driver panics and brakes unnecessarily, by now everyone's too close together and the shock wave propagates backwards until everyone shudders to a halt.
The only technological solution I can see is true active management, where we join the motorway and hook our car into a system that controls our speed and spacing. Dreadful impingement on personal liberties, of course - but we'd get there sooner.
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Have used the M42 section for years and it does not exhibit the problems that the M6 does. Before they put it in the M40/M42 junction was allways stationary around rush hour, not experienced that for a while.
The whole purpose fo the system is to allow traffic to flow, saying you can't expect the M5/M6 junction to flow is admitting that the system doesn't work but he M42/M40 junction shows that it can.
Last night it was showing 60 when I joined at J4 and traffic was flowing well, just before j5 the speed when down to 40 . . . No real reason as traffic was light. Speed went back up to 50 at the next gantry.
Approaching j5 there was definitely a problem with late lane changing that was causing a big backup but the 40 limit was about 2 miles further back.
Maybe I should wait for the roadworks to finish and see what it is like then.
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M6 Active Management - Jn 10-8 - Dave_
