Variable message signs are used to provide en route driver information on road and traffic conditions. To perform effectively, variable message signs must provide adequate target value and legibility and have satisfactory viewing comfort. The objective of the study was to evaluate three different technologies for variable message signs in terms of target value, legibility distance, and viewing comfort. The three technologies evaluated were flip disk, light emitting diode and fibre-optic. Two light emitting diode, four fibre-optic, and four flip-disk signs were evaluated in the field in a human factors study, utilising 62 hired observers. One half of the observers were younger (ages 18 to 31) and one half were older (ages 60 to Observers measured target value and legibility distance from a moving vehicle on the freeway and also subjectively evaluated viewing comfort. Observations were made under four lighting conditions: mid-day, night, washout, and backlight. For target value, legibility distance and viewing comfort, fibre-optic signs performed better than light emitting diode (LED) signs for most conditions. However, both fibre-optic and LED signs have acceptable performance overall. The effects of observer age were identified and documented. (A)
Abstract