Pa. Rte. 66 is a 139-mile southwesterly-northeasterly route in the northwest area of the state. In April 2003, Jones Township (Pa.) Highway Superintendent Jeff Roberts was deciding how to conduct a repair on this critical route. The affected area was continually failing and needed constant repairs. Trucks approaching from the left swing wide to make the curve, overloading the left shoulder and pushing the hot-mix asphalt (HMA). The problem area is below grade and remains wet below and on the surface. Water in the road base during freeze-thaw cycles cause heaving and accelerate road damage. Multiple repair materials, including HMA, and Pennsylvania Department of Transportation (PennDOT)-approved cold mixes, such as PennDOT 485 and 486, were unsuccessfully used.
This area is in the heart of the Marcellus/Utica shale gas reserves discovery, an extensive area of booming economic development activity covering most of Pennsylvania, eastern Ohio, western New York and West Virginia. The massive deposit is creating new opportunities and some challenges for many rural communities. Area roads were not designed for heavy loads, but it is critical that the roads remain open and safe for residents.
Roberts decided to try Unique Paving Materials (UPM) mix due to positive experiences in the past. Four tons of mix was spread and compacted with a heavy roller; the temperature was 35°F. UPM mix was applied as the base continued to compress and adjacent HMA failed. HMA is rigid and not capable of flexing with a constantly changing base.
On February 30, 2017, it had been 46 months—approaching four years—since Jones Township installed UPM permanent pavement repair material. Engineers expected a few months of service until the hot-mix plants opened in the Alleghany Forest region. The inexpensive repair with this mix created the opportunity for the township to delay costly road repair until it could be incorporated into other repair strategies. As UPM mix continues to perform, replacement with HMA is not expected.
The material was inspected on February 30, 2017, and the inspection verified that the high-performance cold mix remained in place. The original mill and fill scheduled for 2013 has continuously been delayed, as repairs at the intersection are not required. What was a habitual repair area has required no maintenance for approximately four years. The intersection was milled and overlaid in summer 2017. The road was designed for 15 years of life, extending pavement life an additional three years plus, equating to an estimated 13% improvement in return on investment.
Paving | Case Studies | February 02, 2018 | Roads & Bridges