The purpose of this document is to report on the performance and various distresses on the MnROAD Mainline HMA sections. Other than simple observations and conclusions, this report will not delve into the causations of the distresses. It is expected that future reports will do so. One observation though is clear; unlike some other test tracks and accelerated test facilities, MnROAD, now eight years old, in a harsh environment, shows that performance is governed as much by the interaction of environment, traffic and material properties as by the interaction of traffic and structural design. It is clear that any proper pavement design must integrate not only structural design but also material properties appropriate to the environment, for all elements of the pavement are under attack, not only by traffic but also the environment, and the environment coupled with traffic.
The Minnesota Department of Transportation along with other partners, constructed forty 500-foot test sections from 1992 to 1994. The site, known as Mn/ROAD, is located along 1-94, 40 miles northwest of the Twin Cities. Since the test sections are located at the same site, they are all subject to the same environmental conditions and traffic load. This makes direct comparisons of the pavement condition of the various cells possible. To accomplish this task, this paper will rely primarily on the use of computer graphics, due to the volume of the data collected and the number of test sections involved, to illustrate the changes in pavement condition that have occurred. Corresponding observations will be very general in nature and should be considered preliminary at this stage. More detailed analyses will be done on a cell by cell basis after all testing and final forensics have been completed. This paper will include a history of rutting, thermal cracking, fatigue cracking, ride, faulting, friction numbers, and construction costs.
