The acronym VMS stands for Variable Message Sign. It is a sign for the purpose of displaying one of a number of messages that may be changed or switched on or off as required (CEN, 2005). This literature review is primarily aimed at describing studies that deal with the interaction between driver behaviour and VMS. The collected references are, for the most part, published in Europe or studies about European conditions, published during the years of 2000 2005. Areas treated in the study are effects on driver behaviour, driver attitudes, design, understanding and recall of VMS, accidents and regulations concerning VMS. Some of the studies are referred to below. In a research project it was concluded that variable speed limit signs were most often obeyed, but display of extra information justifying the speed limit led to higher compliance. A warning sign alone was less effective than the combination of speed limit sign and additional information. An English study describes a warning system for fog on motorways in London. When the fog messages were shown, there was a significant speed decrease. The conclusions of the investigation indicate that the fog warnings caught the attention of the drivers for fog ahead and that the drivers were better prepared to drive safely through the fog. The expectations of the driver and the reliability of the information are two important factors to consider when showing a VMS. The system must work and show correct messages because the drivers expect to get updated information and the information has to be reliable to be obeyed. A Finnish study states that drivers accept VMS and rely on the system. Almost all drivers consider VMS based on real-weather and road condition data to be necessary. The most common advantages mentioned with VMS are improved traffic flow and increased traffic safety. In another Finnish study, drivers declare that with VMS their attention is focused on searching for potential hazards, they test the road for slipperiness and are more careful when overtaking. Most drivers accepted lowered speed limits and found variable speed limits valuable. It is concluded that an effective variable message sign may draw attention from other, fixed signs. This leads to recommending slippery road signs only at critical spots, and variable speed limits for longer road sections. The literature review is supplemented by a behavioural background and recommendations from a behavioural science perspective. (Author/publisher) This document is also available at http://www.vti.se/EPiBrowser/Publikationer%20-%20English/R570A.pdf
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