The tunnel road pavement performance study: final report

This paper reports the results from a full scale test road built in christchurch, New Zealand. The test road was approximately 610 m in length and contained 11 test sections. Seven different basecourse materials were used in the experiment; tar, cement and bitumen treated basecourses, two unbound granular basecourses, and loess soil cement. The performance of the test sections was assessed from measurements of surface distress and the amount of permanent deformation of the pavement surface. The performance of the test sections was also monitored by use of the benkelman beam. All of the test sections with treated basecourse materials failed within the first four years of traffic, with the exception of the 203 mm (8 in) depth of the cement treated basecourse. The performance of the cement treated and soil cement basecourses was especially poor. Three of the four test sections with unbound granular basecourse also failed within the first four years of traffic. From a theoretical analysis, it was deduced that the unbound granular basecourse materials were subject to decompaction during the period of testing. The performance of the granular basecourse sections was closely related to the magnitude of the benkelman beam deflections (a).