Developing Roadway Standards for Ride Quality from the Customer's Perspective (05-0081)
Theodore H. Poister, Georgia State University
Philip M. Garvey, Pennsylvania State University
Martin T. Pietrucha, Pennsylvania State University

This paper reports the findings of research conducted for the Pennsylvania Department of Transportation to develop customer based standards for ride quality on four functional classes of highway including interstate highways, other national highway system (NHS) roads, secondary roads with over 2,000 average annual daily traffic (AADT), and secondary roads with under 2,000 AADT. The field work, in which subjects evaluated the ride quality of predetermined test sections of pavements, was conducted in six Pennsylvania counties in order to incorporate a variety of settings across the state. These subjective ratings were regressed on International Roughness Index (IIRI) values for each of the four highway classes, revealing a fan shaped pattern in which motorist satisfaction with ride quality dropped off most sharply on Interstate highways, less so for other NHS roads, and still less for secondary roads. PennDOT’s current standards for what constitutes “good” ride quality for each of the four road types equates closely with the 70 percent level of motorist satisfaction, while the standards for “excellent” ride quality coincide with the 90 percent motorist satisfaction level for all but the lower volume secondary roads. The results also suggest that motorist satisfaction with ride quality is extremely sensitive to IRI in rural settings, moderately sensitive to IRI in urban settings, and less so in major metropolitan suburban areas. This pattern is the reverse with respect to NHS roads, and for secondary roads motorist satisfaction is very sensitive to IRI in rural areas and less so in urban and suburban areas.