Factors Affecting Maintenance Overlay Ride Quality: 1996 Rideability Status

About the report:

In early 1996, the Virginia Transportation Research Council initiated a formal analysis of the factors affecting overlay ride quality. As part of that effort, a statewide, multi-year survey of the ride quality for both new overlays and pavement awaiting overlays was initiated. Also, during the 1996 construction season, the Virginia Department of Transportation began to pilot a special provision for pavement smoothness. This new provision is somewhat unique in that it replaces the California type Profilograph with a South Dakota style road profiler. Correspondingly, ride quality targets and pay adjustments, previously established in terms of the Profile Index (PI), are expressed in terms of the International Roughness Index (IRI). This interim report presents a summary of the ride quality of Virginia's maintenance overlays as observed for the 1996 construction season. The information covers nearly 1,600 lane-kilometers (990 miles) of overlay in 61 counties of eight construction districts. The findings suggest that the achievable smoothness of an overlay is highly influenced by functional classification. For example, the average smoothness of overlays on interstates was well below the specified target while most overlays on two-lane primary highways would have fallen just short. In general, current targets for ride quality (in terms of IRI) appear to be well within the capabilities of most of Virginia's paving contractors. Preliminary results of the pilot study indicate that the presence of a smoothness specification can have a distinctly positive influence on overlay ride quality.

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