The condition of the U.S. highway system has been and continues to be a major concern of both the highway and trucking communities. This is understandable given the fact that in 1990, combination vehicles with five or more axles accounted for 91 percent of the 18,000 pound equivalent axle loads (ESALs) on rural Interstate highways. This heavy vehicle traffic and the pavement system it travels on combine to generate a perpetual cycle of pavement deterioration and rehabilitation. Increasing truck traffic leads to predictable pavement damage that in turn contributes to potentially increasing dynamic loading of the pavement. This cycle continues until some form of pavement rehabilitation is undertaken. The trucking community alters the design and operation of their vehicles largely due to economic considerations (profit) but also in response to the ride quality (or lack thereof) of the infrastructure to which they are bound. On the other hand, the pavement community is constantly updating design and construction practice to improve pavement performance. Unfortunately, both parties develop a form of "technical tunnel vision" and work to resolve some of the same concerns without the benefit of a possible mutual effort. As such it was recognized that there was a need to improve our mutual understanding of truck pavement interaction. Often, but not always, a beneficial change in one community (such as smoother pavements) benefits the other (less truck/cargo damage).
This report is part of a multiphased research project entitled "Truck/Pavement Interaction" conducted jointly by the University of Washington, University of California-Berkeley, Washington State Department of Transportation (WSDOT), California Department of Transportation (Caltrans), and PACCAR, Inc. This is an attempt to promulgate a mutually beneficial dialog between the pavement and trucking communities. The objective of the research is to investigate how different truck suspensions, tire/axle combinations, tire loads, and tire pressures affect pavement response and conversely how pavement condition affects truck performance and damage. These objectives will be accomplished by operating instrumented trucks over an instrumented pavement section.