Light test warning lights

A feasibility study on the visibility of warning lights on road work vehicles.

In a feasibility study, the visibility of three different so-called warning and stop lights was analyzed and compared, both individually and in combination, under varying conditions on a straight line, curve, crest and dip, and in daylight and darkness. The lights were mounted on a mowing vehicle, a grader.

The study was carried out along two stretches of road with a good mix of alignment with hilly and curvy terrain, long straight stretches and nearby forest landscape. The assessment of the lanterns was documented and resulted in a total of 866 observations. The lights had different beam angles, which affected visibility in curves, crests and hollows. One of the lights was so bright that in some cases it dazzled in the dark.

The flash pattern considered to give the best detectability under all conditions was a rapid double flash with a (short) pause in between. In comparison, the parallel flash provided by the cut-off lights, at a frequency of 60 g/min, was considered to be rather monotonous and "sleepy".

The assessment is that only one ramp of the type tested, with double flash, provides very good visibility that works well in all the situations tested except for darkness, when it dazzles at short distances.

The assembly and connection instructions supplied with all the lights were inadequate and may lead to incorrect installation of the lights.