Japan Highways conducted tests on the visibility of VMSs at the testing course of the Public Works Research Institute of the Ministry of Land, Infrastructure and Traffic on the assumption that road users drive at a speed of 140 km/h on New Tomei Meishin Expressway. It is possible to use three-coloured LED elements in the form of symbols for the current VMS. Because it is necessary to use symbols that anyone can recognise including the elderly and foreign drivers, it is thought to be more effective to use traffic control signs that are already recognisable instead of unique symbols. Results indicated that visibility could be improved by utilising traffic control signs that drivers are already familiar with and improving the coloration of symbols on the current VMS. Therefore, the best solution is to provide a space that is exclusively designated for the display of symbols on VMSs and to always display the symbols related to the letter information. As a measure to improve visibility at night, adding white frames is effective, as is often the case for many road signs in Europe. The white frames are also effective in improving visibility during the day regardless of the type of background, such as mountains or the sky. For the covering abstract see ITRD E209471.
Samenvatting