AASHTO Journal, 19 September 2014
Experts examine an “ultrathin bonded wearing course” during an SHRP2-hosted implementation workshop in Minnesota recently. Photo courtesy David Peshkin.
More than 165 transportation professionals from 30 states and Canada participated in a three-day workshop earlier this month to explore strategies for preserving high-traffic volume roadways, including new guidance developed through the second Strategic Highway Research Program (SHRP2). The Minnesota Department of Transportation hosted the September 3–5 workshop, which featured presentations, discussions, and a site visit on successful strategies for extending the life of asphalt and concrete high-traffic roads.
“There are many preservation techniques to use, if you understand what it takes to build the project and how it can improve the life of your roads and stretch your transportation budget,” said Jerry Geib, MnDOT Pavement and Materials Engineer.
MnDOT is one of 14 transportation agencies that received funding from the Federal Highway Administration/AASHTO SHRP2 Implementation Assistance Program to test, implement, and share results on pavement preservation treatments using the Guidelines for the Preservation of High-Traffic-Volume Roadways (also referred to as R26). The guidelines and its companion report, Preservation Approaches for High-Traffic-Volume Roadways, are the first systematic and comprehensive resources designed to expand use of pavement preservation on high-traffic roads. These resources provide the technical background and decision-making framework needed to bring preservation strategies widely into play for high-traffic roads.
The Minnesota workshop included a visit to MnROAD, a MnDOT-operated cold-region testing facility and laboratory located 40 miles northwest of Minneapolis–St. Paul. Originally constructed in 1994 using state and federal funding, MnROAD consists of three unique road segments divided into 60, 500-foot test sections:
- A 3.5-mile mainline interstate roadway that carries 29,000 vehicles per day with 13 percent trucks;
- A 3.5-mile bypass interstate for live traffic diverted off the mainline when it is undergoing treatment and testing; and
- A 2.5-mile closed-loop low-volume roadway loaded with an 80,000-pound five-axle tractor-trailer.
Workshop participants walked test segments on the mainline Interstate to examine and discuss the preservation treatments in use with members of the MnDOT research team. Treatments on display included flexible microsurfacing, ultra-thin bonding wearing course, and chip seal. MnDOT’s shop also displayed construction and performance monitoring equipment used to apply treatments and assess results.
Additional real-life examples of pavement preservation treatments on high-traffic roads are mapped out in a new SHRP2 brochure that highlights the work of the 14 agencies that received FHWA funds to apply treatments using the Guidelines. Approximately 13 different preservation treatments are being tested on more than 30 roads with average daily traffic ranging from 5,000 to more than 50,000 vehicles.