ESTABLISHING RELATIONSHIPS BETWEEN PAVEMENT ROUGHNESS AND PERCEPTIONS OF ACCEPTABILITY (WITH DISCUSSION AND CLOSURE)

A psychological scaling experiment was conducted in Wisconsin to establish relationships between pavement roughness and users' perceived need to improve the road. A total of 32 road segments were selected for user evaluation. Except for their surface, they had very similar characteristics (speed limit, length, terrain, traffic volumes, scenery, etc.). Physical roughness was measured with both a response-type instrument (roadmeter) and a profilometer. Fifty paid subjects were selected randomly from the general population. They were asked to rate ride quality on both the traditional Weaver/AASHO categorical scale and on a newly designed magnitude estimation scale. In addition, subjects were asked, using a Likert scale, about their willingness to resurface and were asked to estimate the amount of extra time they would be willing to spend to avoid a particular segment, considering its roughness. The experiment yielded several useful mathematical relations between physical roughness and users' willingness to resurface. It was found that the magnitude estimation scale was preferable to the Weaver/AASHO scale for measuring subjective roughness. Surprisingly, the roadmeter was better than the profilometer for measuring physical roughness.