This article discusses the many factors relevant to variable message sign (VMS) implementation, and how they can be applied to implementing individual VMSs. The original basic VMS technologies - lamp bank, reflective disk, and rotating drum - are now considered mature, and are still used throughout the VMS industry. However, the rising demand for VMSs, as an integral part of the expanding Intelligent Transport System (ITS) industry, has stimulated the development of new display technologies. At the same time, users - including departments of transportation and highway, bridge, and tunnel authorities - have gained more sophisticated knowledge of VMSs. They need to realise that drivers' minds are focused on the quality of the VMSs. Common issues facing authors and users of VMS specifications are various aspects of display type, display size, reliability, software, and service. General criteria for selecting a VMS company are expertise, reliability, compliance, stability, reputation, leadership, commitment, value, integration, and ability to handle hybrid VMS capabilities. A VMS company needs to `come up to speed' very quickly, because most ITS projects are likely to involve catch-up situations where specifications have already been laid down.
Samenvatting