Injury accidents on British roads would be reduced by 35% as a result of introducing a system that automatically limited the top speed of road vehicles to the prevailing speed limit road, while imposing lower speeds when road conditions demanded it. This is the major finding of Phase 1 of a three-year research project on "External Vehicle Speed Control". The project is being jointly carried out by the University of Leeds and the Motor Industry Research Association (MIRA), and is being funded by the Vehicle Standards and Engineering Division of the Department of the Environment, Transport and the Regions.
The prediction on accident savings is based on an analysis of the relationship between speed and the probability of accidents of various types and a calculation of how the new system would alter vehicle speeds, particularly those of the fastest drivers. The project leader Dr Oliver Carsten of the Institute for Transport Studies at the University of Leeds said: "It is hard to conceive of any other single intervention or system that would achieve comparable reductions in injuries and fatalities. The predicted reduction is far greater than that achieved by the compulsory wearing of seatbelts, perhaps the most successful single measure to date."
A less sophisticated system that merely limited top speed to the legal speed limit for the road in question would result in a 20 percent reduction in injury and fatal accidents. For nearly every configuration of intelligent speed limiter, the benefits in terms of accident savings are considerably greater than the cost of introducing the system for all vehicles. For many versions of the system, the benefits would outweigh the costs by a factor of more than 3 to 1.
The project found that urban residents are willing to pay approximately £15 a year through local taxes to have their streets equipped for automatic limitation of vehicle top speed. This could provide a cheaper and more effective alternative to current methods of traffic calming. Drivers are willing to pay £148 a year for speed limiters, provided the system is applied everywhere.
Considerable work has also been carried out on concepts for the communications so that the vehicle would "know" the permitted top speed and on various ways in which the engine, gearbox and perhaps brakes could be controlled to achieve the speed limitation. There are a number of alternatives both for the communications and for the control mechanism and these will be investigated further in the later phases of the project.
The next phase of the project will study driver behaviour with speed limited vehicles, both in the laboratory, on a driving simulator, and on real roads. It will also look at the potential side effects of the system in terms of fuel consumption, pollution and travel time. Mark Fowkes, manager of the EVSC project at MIRA, said: "The next stage of the project will seek to understand how the potential benefits of EVSC can be maximised whilst taking into account both driver acceptability and technical feasibility."