MS4: a sign of the times

The latest type of Variable Message Sign (VMS) developed by the Highways Agency is the MS4 (Motorway Signal Type 4). It is intended to optimise roadside information delivery in the early 21st Century. A prototype has been built and encouraging results have been obtained from an Off-Road Trial and plans for an On-Road Trial are well advanced. This article outlines the MS4´s development process. A number of different influences led to the development of the MS4: the quicker comprehension afforded by pictograms compared with text; the fact that existing central-reserve matrix signals will not meet the expected levels of driver information; the desire to minimise the visual intrusion and a desire to minimise whole life costs