Dear Sir or Madam,

Can you please supply details of the publics need for M4 motorway matrix boards? I'd like to know who commissioned them , why they thought the need was there and why they are so badly maintained from a data point of view. In short, please justify the disruption to traffic versus the CURRENT benefit. Often the data is wrong, meaningless or just completely pointless.

Yours faithfully,

Steve Cox

VMS Doc Issue 3 (2).pdf
benefits of midas.pdf

Dear Sir

Thank you for your email concerning the matrix boards on the M4. As you will appreciate there are many different types of VMS on that route, and with regard to specific maintenance issues we would require greater detail about the problems you have observed.

Variable Message Signs (VMS) are highly visible tools which can relay safety messages and other information to drivers whilst on their journey. A high proportion of the legends are set automatically by the MIDAS system (as explained below) and this was the basis for the original business case. They are also used to display tactical (regional) information, strategic (longer distance) information and more recently travel and delay times between specific nodes on the network. Currently, we have 4 different sizes of VMS signs in use, displaying either 2 lines of 12 characters, 2 lines of 16 characters, or 3 lines of 18 characters each and one that is capable showing pictograms.

VMS are set from our National Traffic Control Centre (NTCC) and from our seven Regional Control Centres (RCCs). These centres continuously gather information from a variety of sources, and set messages accordingly. The criteria that are used to set electronic speed advisory signs on the motorway are contained in the Policy & Procedures for the use of Matrix Signals by the Regional Control Centres (See attached document) which has been agreed between the Highways Agency and the Association of Chief Police Officers (ACPO). These signs can be set automatically by the system software or manually by the HA RCC staff. The decision to set signals should be based on the information available and is the responsibility of the officer (Traffic Officer or police in charge of the incident at the scene) or the operator in the control room. Where an advisory speed limit sign is set manually by the operator, the decision on the advisory speed displayed is based upon information received from a number of sources including:
* CCTV
* Road users at the scene before a Traffic Officer or Police have arrived at the scene
* Traffic Officer or Police at the scene
* Outside bodies such as the Highways Agency Managing Agent Contractors
* Authorised organisations such as fire and ambulance service staff
* Automatic incident detection systems which raise awareness in the control room (these systems can be linked to CCTV)

The RCC operator should also take into consideration any specific local requirements that might apply. In addition, the operator will need to balance information and recommendations received from patrols against any situation that might have arisen elsewhere.

A RCC operator who has set signals manually has to monitor the situation to revise the signal setting as necessary, to prevent the setting of a misleading or contradictory series of signals and VMS messages and remove them when the incident has cleared. The automatic system will clear the signal once the incident has cleared.

In terms of benefit VMS signs are primarily for safety, to help prevent drivers from running into the back of a queue. The majority of settings on the VMS are set automatically by the Motorway Incident Detection and Automatic Signalling (MIDAS) system. It is designed to work without operator intervention as this enables an immediate response to the detection of a queue, warning motorists of slow or stationary traffic ahead.

MIDAS automatically sets advisory signs and signals to 40mph / QUEUE CAUTION to advise of the queue ahead, with further 50mph / QUEUE AHEAD and 60mph / QUEUE AHEAD warnings before that. The latest research shows that the MIDAS system, which is installed on over 1000 km of motorway, reduces injury accidents by 13% and congestion by 8%, leading to overall economic benefits of over £60M per year.

When traffic is moving at variable speeds MIDAS automatically adjusts any signals previously set to reflect changing traffic conditions. MIDAS is designed with a built in delay between traffic conditions returning to normal and the system switching off. This is to prevent MIDAS switching on and off at frequent intervals in stop/start conditions. A more detailed paper is attached.

Thank you again for your comments, which are helpful to us in identifying improvements. If you have any further questions or comments regarding variable message signs please contact the Highways Agency Information Line (HAIL) on 08457 50 40 30.

If you are unhappy with the way we have handled your request, you may ask for an internal review. A leaflet detailing our internal review process is available. If you require a copy, please phone the Highways Agency Information Line on 08457 50 40 30; or e-mail [Highways Agency request email]. You should contact me if you wish to complain.

Paul Whitehead, Senior Policy Advisor
Highways Agency | 5 Broadway | Broad Street | Birmingham | B15 1BL
Tel: +44 (0) 121 678 8000
Web: http://www.highways.gov.uk
Safe roads, Reliable journeys, Informed travellers
Highways Agency, an Executive Agency of the Departmen t for Transport

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