Driver response to a new, more informative, motorway signal has been measured over an 18 month period on the M1 motorway in Bedfordshire. The new signal has three panels. The top is the same as existing signals and can show an advised maximum speed or indicate a closed lane. A second panel shows one of twelve pictograms which represent the nature of the hazard and a third panel gives, where appropriate, the distance ahead. The added information resulted in improved response from drivers in that they slowed down more, speed distribution was reduced and there was an overall reduction in close following in reasonable visibility. The cost of supplying and installing the new signal was estimated at 5000 per kilometre in 1979 prices and their installation could be justified if one accident could be prevented each year on each 20 kilometres of motorway. (A)

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