Thirty hot mix asphalt (HMA) test sections were constructedin Michigan (1992), Wisconsin (1992), Colorado (1994), and Pennsylvania(1995) to evaluate the effectiveness of twelve different longitudinaljoint construction techniques. The performance of these test sectionswas evaluated in 1996 after one to four years in service.

The joints with high densities generally show better performancethan those with relatively low densities. The Michigan joint technique(12.5 mm vertical offset and 12:1 taper) appears to have the bestpotential of obtaining a satisfactory longitudinal joint. Thecutting wheel and the edge restraining device techniques havegood potential but are too much operator dependent to obtain consistentresults. Among the three different joint rolling techniques usedin all four projects, rolling the joint from hot side generallygave the best performance followed by rolling from hot side 152mm away from the joint. Paver manufacturers should consider modifyingthe paver design to obtain a Michigan type, high density unconfinedwedge in the lane paved first. Highway agencies should specifyminimum compaction levels to be achieved at the longitudinal joint