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Chapter 8: Motorway Communications and control

Having dealt in previous chapters with all those activities that contributed to the construction of the motorway network, we now come in this chapter to a consideration of the all-important communication and control systems needed to allow motorists to use the motorway safely and efficiently when it is opened to traffic.

The chapter has been compiled by Derek Clark, previously Chief Electrical Engineer in the Department and a former Head of Traffic Communications and Control Division.

The chapter begins with a brief look at early developments before moving on to a survey of more recent practice and a glimpse into the future, all as described in a contribution to the Archive by Aubrey Stannett, Head of Network Communications Operation and Maintenance in the Highways Agency. Another important contribution to the Archive came from Peter Poole, a senior engineer in the Department from 1964 to 1975.

The development of motorway communication and control systems involved the work of countless dedicated Department staff, contractors and consultants. It is clearly impossible to acknowledge them all individually but what must be recognised is that collectively they made an invaluable contribution to the safety and ease of travel on motorways. As Head of Traffic Engineering Division John Duff assisted by Ernest Walker and a small supporting team initiated the motorway communications development programme in the early 1960s. In 1974 the motorway part of the Division was merged with Traffic Control Division to form Traffic Communications and Control Division under the leadership of Brian Cobbe; in 1976 he was succeeded as Head of Division by Derek Clark, who was in turn succeeded in 1983 by Stan Wilson.

In the second part of this chapter, the ‘view from the centre’ is augmented by an example of traffic communication and control in action at the interface between a motorway and an urban network as exemplified by the Lagan Bridge in Belfast. The bridge provides an important cross-harbour road link and presented a considerable challenge in terms of traffic management because of the interaction between the control of traffic using the motorway and traffic in the surrounding urban area. This part of the chapter draws on a more comprehensive paper prepared for the Archive by Billy McCoubrey, formerly Chief Road Engineer in Northern Ireland with support from colleagues including in particular Brian Maxwell and Bernie Frayne.

In the third part of the chapter we address the traffic management problems arising when a motorway requires major maintenance. This part of the chapter draws on a contribution to the Archive by Doug Mathews who led the research team at TRRL that was responsible for this work. It shows how traffic control at roadworks requires careful consideration of road layouts designed to guide traffic safely through a restricted width of carriageway in particularly demanding circumstances. Handling of road traffic accidents and other incidents is particularly challenging in the confined space of the roadworks but we will demonstrate that by carefully planned and implemented research it was possible to carry out major roadworks while minimising delays to road users and adverse impact on safety. The chapter illustrates the importance of collaboration between all the stakeholders in the formulation, execution and implementation of research with special mention for Doug Maclean at TRRL, Bill Harlow in Traffic Engineering Division, Ken White of Staffordshire County Council and Geoff Stapleton of Hereford and Worcester County Council, along with others from Highway Maintenance Division, the Health and Safety Executive and the police.

Finally, we the Editors of this volume offer a piece of crystal ball gazing into the future of interurban motorways. We note some of the more significant factors driving the evolution of interurban road transport and attempt to assess the emerging problems and suggest ways in which the changes may be managed. The exercise is brief and we claim no specialist expertise in predicting the future but the volume would seem incomplete without this end piece.

But before turning to the main substance of the chapter, and the sources from which it was compiled, it may help the reader to briefly review the main channels of communication available for the control of motorway traffic. These channels of communication have been devised to enable the Department to deliver the best level of service to motorway users. Success may be judged by improvements under the following headings:

  • volume of traffic handled and throughput;
  • reliability in journey times;
  • comfort and safety;
  • provision of effective guidance on route selection;
  • reduced energy and pollution.

The channels of communication available to pursue these aims include:

Road design: The road itself can assist the driver through careful attention to geometric design, curvature and superelevation, line markings, cats eyes, fixed signing, lighting and so on. Road design is a major, passive contributor to the comfort and safety of motorway users.

Operator and police to driver: Better quality information can be passed to drivers through variable message signing and through the car radio; information to help advance planning of journeys can be disseminated through a wide variety of other media such as visual displays at Motorway Service Areas, radio and television, telephone helpline services and the Internet.

The network may be monitored for congestion and adverse weather. The information is of value to the operator and to drivers using the motorways as exemplified by the Trafficmaster system and the journey planning computer software and satellite navigation systems now widely available. Undoubtedly this is an area for future exploitation to the advantage of the operator and other service providers and motorway users alike.

Feedback from drivers: Feedback from drivers is a valuable source of information on, for example, problems due to congestion or accidents. At present the driver must relay messages through the telephone system but increasingly the time to disseminate information is being shortened by direct communication with local radio stations and other providers of travel information.

Directly control of traffic by the operator and police: Already, interactive mandatory speed limits or diversions can be imposed to manage traffic and minimise congestion or cope with road traffic accidents. For the future direct control of the speed of individual vehicle will make it feasible to increase motorway traffic flows by controlling entry and exit and making up convoys. One possible longer term future scenario could see the motorway network used to provide a premium service for vehicles merging into pre-booked slots and then operating under automatic control until the pre-booked exit is reached - the ultimate integrated transport system. Obviously this is but one of many possible visions of the long term future, all of which hold many uncertainties and problems.


The National Motorway Communication System (NMCS) is a computer-controlled network operating emergency roadside telephones, matrix signals, variable message signs and other devices on the Highways Agency’s core network; the core network comprises all motorways and trunk roads for which HA is the highway authority. Telephones positioned at regular intervals alongside all motorways and some trunk roads on the core network are used by drivers to report emergencies, breakdowns and accidents. Signals are positioned at regular intervals along motorways and a few trunk roads on the core network. If a hazard should arise, these signals display appropriate warnings to slow down or divert traffic. Normally, an operator from a Police Control Office (PCO) activates the information display.

Some sections of motorway are equipped with closed circuit television (CCTV) to monitor traffic at vulnerable sections such as motorway interchanges and bridge and tunnel approaches. Other equipment includes underground loop detectors for traffic monitoring or incident detection, variable message signs and fog warning devices. These are also connected to the local PCO.

As an executive agency of the Department, HA is responsible for the type approval of all traffic control systems and equipment. By way of this delegation, HA provides, operates and maintains the NMCS on all motorways and some trunk roads on its core network.

NMCS is provided on the motorway system to:

  • Ensure as far as possible the safety of roads users;
  • Enable assistance to be summoned in the event of an emergency, breakdown or other problem;
  • Give motorists information about hazards, traffic or weather problems together with suggested speeds or lane information;
  • Facilitate surveillance of critical points on the network and in some instances provide automatic warnings of congestion or other disturbance to the flow of traffic;
  • Display compulsory speed limits supported by speed enforcement systems in certain busy sections of motorway;
  • Make best use of the core network.

Motorway Communications and ControlThe design, operation and maintenance of NMCS aims to fulfil the undertakings set out in ‘The Road Users Charter’. The motorway communications equipment is installed through contracts let by HA. These contracts include public and private sector funded procurement; the latter arise by way of ‘design, build, finance and operate’ schemes and other Private Finance Initiative projects such as the proposed new National Traffic Control Centre. All motorway communications systems are designed and manufactured to specifications that ensure they meet all appropriate safety and reliability requirements. Rigorous standards for maintenance require that faults are rectified promptly to ensure a high level of availability of systems to the public. Motorway communications are operated by the police using a standardised set of equipment in the PCOs following a code of practice drawn up by the Association of Chief Police Officers in consultation with HA. Over the last 40 years various systems have been commissioned to meet the ever increasing demands on the core network.

The following subjects are covered in the printed document (Volume 2):


Signal and Signs
Closed Circuit Television
Accidents and Stationary Vehicles
Fog and High Winds


National Motorway Communication System: 1
National Motorway Communication System: 2
Motorway Equipment
Control Office Base System
Future Priorities


Control System Design
Interfaces and Interactions
Developing the system


The Early Years
Segregated Contraflow
Dissemination of Knowledge
Full Contraflow
M5 in Worcestershire
High Speed Crossovers
Mobile Lane Closures