The number of VMS signs on English motorways has increased substantially in the last few years. Many of these can display text messages and can be used for a number of different purposes. They can, for example, give warning of hazards with greater detail than previously possible, or display a congestion warning that offers drivers the opportunity to choose an alternative route. In principle, non-traffic messages unrelated to immediate traffic conditions can be used to give information about future road works or safety messages, either general or related to particular campaigns. Evidence concerning driver attitudes to non-traffic messages on VMS, indicates that a large number of drivers are in favour of the wider use of safety-related non-traffic messages on VMS. Traffic data indicate that these messages are likely to have some effect on driving behaviour, at least in the short term. A study investigating the effect of VMS message format and content on the efficiency of message recall found that there was little effect on recall ability when information was presented in different orders. The effect on recall of adding extra information was investigated and also the information content of delay / journey time messages. A subsequent investigation was designed to measure the effect of displaying various types of VMS message on the speed and accuracy of route choice decisions. Three types of message were used: non-traffic, tactical and strategic. The presence of contradictory messages on VMS was also investigated. A further study measured the time to locate a target destination and the accuracy of a navigation decision for eight different sign-sequence combinations of VMS and ADS. These included VMS mounted on gantries with ADS, verge-mounted as opposed to gantry-mounted VMS, and sequences with only one BMS. The final study looked at three of the eight sign sequences and used the main TRL Advanced Driving Simulator. The effect on driving behaviour as well as response time and accuracy was measured. (A)

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