Conspicuity of Flashing Warning Lights at Dutch Open-Level Railroad Crossings

This study addresses the questions of whether it is possible to enhance, with relatively simple means, the visual conspicuity of open-level crossings with automatic flashing lights. Slides of AKI-crossings, with various modifications, shown in their natural surroundings, were used as stimuli. Subjects had to identify the color of the signal light as fast as possible, while at the same time performing a tracking task. The main result was that conspicuity of the signal lights could be enhanced significantly by either of the following modifications: a threefold increase in luminance, a larger background screen, or a more abrupt transition of the lights. Neither a change in the color of the various parts of the AKI (from red-white to black-yellow), nor doubling flash frequency was effective in raising the conspicuity of the signal lights.