EXAMINATION OF PAVEMENT DETERIORATION IN THE PRESENCE OF AUTOMOBILE TRAFFIC

In recent years, and particularly in association with discussions of the federal highway cost-allocation study reported to Congress in 1982, a variety of statements and reports have surfaced alleging that automobile traffic, such as that on the Merritt Parkway in Connecticut and the Baltimore/ Washington (B/W) Parkway in Maryland, causes as much overall pavement damage over the long term as does mixed truck and automobile traffic on highways of the same design in the same areas. A study was undertaken at the request of the Association of American Railroads to perform on-the-spot condition surveys of the Merritt Parkway, the B/W Parkway, and adjacent Interstate highways in both areas. In addition, intensive searches were made of records of the Connecticut Department of Transportation (which constructed and maintains the Merritt Parkway), FHWA (which built the B/W Parkway), and the U.S. Park Service (which maintains the B/W Parkway). The records of construction details and maintenance costs associated with the pavements under consideration were incomplete; nevertheless, a significant amount of information was obtained on which certain conclusions could be made. Basically, the results of the study clearly demonstrate that under the weather conditions, environment, construction materials, and pavement design and time frame involved in these cases, the damaging effect of trucks on heavy-duty highways is indeed greater than the damaging effect of automobiles. The data available and the scope of the study did not make it possible to derive quantitative relationships from these findings; however, they clearly refute the assertions that pavements deteriorate as rapidly under automobile traffic alone as they do under mixed truck and automobile traffic.