Variable message signs (VMS) are becoming an increasingly attractive way of providing useful traffic information to drivers; when appropriately sited, they can substantially affect traffic distribution within a road network. For example, this effect is recognised in Southampton, England, where new VMS are being installed at key urban locations, as part of the ROMANSE and ENTRANCE projects. In relation to the ROMANSE project, several factors are discussed, which are likely to influence the effectiveness of VMS; they include: (1) the proportion of drivers reacting to the VMS message; (2) timely implementation of that message; (3) the `normal' level of congestion within the road network; and (4) whether pre-trip information, for example via broadcast media, is also available. Some findings are reported of new research, aiming to develop better understanding of issues related to the effectiveness of VMS information. Modelling was conducted, using the `single day' (SD) version of Route Guidance CONTRAM (RGCONTRAM), based on the CONTRAM CONtinuous TRaffic Assignment Model. A radial `test' network was developed, for which an artificial origin - destination (O-D) matrix was also created. Four factors, influencing VMS benefits, are discussed, and several findings from the modelling exercise are outlined.
Abstract