See also
http://www.ukpoliceonline.co.uk/ind...-the-ha/?&p=419364&hl=Birmingham&fromsearch=1&
Thank you for your call to the Highways Agency Information LIne regarding the current works on the M6. I am responding on behalf of the Birmingham Box Managed Motorway (BBMM) Phases 1&2 scheme which is being implemented at Junctions 4 - 5 and J8 - 10A.
In response to your questions:
1) Junctions 4-5 is scheduled for completion and hard shoulder running by Dec 2009
Junction 8 - 10A is scheduled for completion Spring 2011
2) This is how the system works:
The main purpose is to manage congestion. It can however also be used to manage the traffic around incidents on the motorway.
The two main components are variable speed limits, or controlled motorways, and hard shoulder running.
During normal motorway conditions, with no incidents or congestion, all the electronic signs will be blank and all normal motorway rules apply.
As congestion begins to build up, or an incident is detected, the sensors underneath the road surface will detect slower moving traffic and the computer system calculates the most appropriate speed for the traffic. This speed limit will then appear on the overhead signals, with a red ring surrounding the number indicating that it is a mandatory speed limit. A red cross will appear over the hard shoulder indicating that the lane should not be used except in the event of an emergency or breakdown.
By reducing the speed on the motorway we are able to smooth the flow of the traffic, reducing stop-start driving conditions. Reducing speeds also helps prevent breakdown of traffic flow and increases traffic throughput. The uniform speed across all three lanes also reduces the need for drivers to change lanes.
If congestion continues to build up the sensors will alert operators in the regional control centre that hard shoulder running may now be appropriate. The operator will then be taken through a semi-automated system using CCTV cameras to check the hard shoulder is free of debris and vehicles. From the first alert the hard shoulder between any two junctions can be opened within minutes, giving an extra running lane to provide additional capacity at the busiest times of day.
When the hard shoulder is open to motorists a speed limit appears on the electronic signal above the hard shoulder. The speed limit will be the same across all four lanes, again reducing the need for drivers to change lanes. A message will also appear on the electronic driver information signs to inform motorists that the hard shoulder is available for use. In the event of an emergency or breakdown, you should use one the emergency refuge areas.
3) When the speed cameras are in operation there is a built in 60 second time delay from the switching of the sign/speed limit to when the cameras will actually enforce at the new speed.
More info on the scheme can be found at
http://www.highways....ledge/1356.aspx
If you have any other queries regarding this scheme please forward them to our project email at:
BBATM@highways.gsi.gov.uk
Regards
Persons name
Business & Information Manager
BBMM 1&2
C5 Broadway, Broad St
Birmingham
B15 1BL
All credit goes to the HA for a very efficient and highly professional response.