The use made of the speedometer as an aid to driving.

This note describes a study of the use which drivers of motor vehicles make of the speedometer when making changes of speed, particularly in circumstances where an appropriate speed is likely to be important to safety. By the combined use of behavioural observation and questionnaire techniques a comparison was also made between what drivers say they do, and what they actually do, on the road. The behaviour of 30 subjects was observed while they drove over a route chosen to include most situations where a speedometer might reasonably be considered helpful to safe driving. The results showed that there were wide differences in the use made of the speed-ometer by different drivers and that the drivers thought they used a speedometer far more than they did. The only exceptions were on a motorway or in towns. Asked whether they thought they would drive loss safely without a speedometer, 22 drivers (70 per cent) said they thought not