In the summer of 2003, Minnesota’s Department of Transportation (Mn/DOT) conducted a series of preventative maintenance activities to the hot mix asphalt (HMA) test cells at its MnROAD test facility. The activities took place on MnROAD’s mainline test road, which consists of 3 miles (4.8 km) of two lane, westbound Interstate Highway 94 with an average daily traffic (ADT) level of 25,000.
Open to traffic in 1994, the fourteen HMA test cells were in need of maintenance to address rutting, top-down cracking, and cupped transverse cracks. Each cell is 500 feet (150 m) long and is designed as a 5-year or 10-year pavement with a variety of mixtures and bases.
Mn/DOT applied a series of maintenance activities either alone or in combination for re-sealing sealed transverse cracks, leveling out cupped transverse cracks and filling rutted wheelpaths. Two control cells, one 5-year and one 10-year, were left alone to compare the restored cells against. The goal was to restore the ride quality of the mainline cells, measured by International Roughness Index (IRI).
The ride quality improved 48% four months after the application of the maintenance work. Early results showed leveling of the cupped transverse cracks prior to applying a thin maintenance surface (TMS) provides better ride quality results, as does a double application of the TMS compared to a single application. The results gathered are early in the life of the treatments and they will change in time.
