Abstract
Retroreflectivity is known to be correlated to levels of traffic capacity or uniformity of vehicle speeds. The present paper uses the nation wide data base of freeway retroreflectivity then tries to single out the characteristics of retroreflectivity according to levels of influencing factors. Currently, the ergonomic and allowable minimum retroreflectivity for Korean freeway is 110 and 90 mcd/m2/lux for the white and the yellow pavement marking, respectively. It was resulted that observed values do not satisfy the minimum value uniformly. Following levels of influencing factors such as changes by 12 months, annual daily traffic, and material characteristics such as thermoplastic, durable, epoxy, water-borne, and solvent-borne paint, the observed values shows gaps from the minimum values. Consequent conclusions maybe be inferred. First, as observed shows gaps from the minimum values, there should be ergonomic and materialistic study performed for narrowing the gaps. Secondly, for the higher traffic volume road section, there should be countermeasures to maintain uniformity of retroreflectivity. Thirdly, as it is found out there is gaps between observed and ergonomic minimum retroreflectivity, there should be proper ways case by case to choose the materials of pavement markings before painting works. Fourth, as standard deviations of observed retroreflectivity for all influencing factors are considerable, ways to sustain uniformity as one of traffic control devices should be studied.