By Bob Horan, P.E.
An article entitled “West Virginia High Performance Intersection Project” was published in the Fall 2002 issue of Asphalt Magazine. That article told the story of how the West Virginia Department of Highways (WVDOH) had used polymer modified asphalt (PMA) meeting the requirements of PG 76-22 to develop a rut resistant hot mix asphalt (HMA) material for the first time in that state. The project site was an intersection of two major coal haul routes, US 52 and WV 37, at Fort Gay, West Virginia. The project included full depth rehabilitation of the areas where rutting was the worst with a 37.5 mm base mix and a 12.5 mm surface mix and a two inch “mill and fill” inlay using 12.5 mm surface mix for the remainder of the intersection.
In July 2008, Larry Barker and Stuart Groves of WVDOH and I visited the intersection to evaluate the success of a “high performance” HMA intersection after six years of coal-haul traffic. We observed only minimal rutting despite the pavement being subjected to hundreds of very heavily loaded coal haul (slow moving or stopped) trucks on a daily basis. We estimated that the rutting was no deeper than ¼ to ½ inch. Larry Barker, Asphalt Technical Section Leader for the WVDOH Materials Division, is the lead technical person in the state when it comes to asphalt materials and pavements. Larry was involved with the mix design and construction of the original project and was quoted in the original article.
After seeing the intersection’s performance, Barker said, “WVDOH has been very pleased with the performance of the Fort Gay intersection. Where standard mixes used in previous mill and overlay applications were severely rutting within 6 months at this location, there has been minimal rutting over a six year period since the rehabilitation using the rut resistant HMA materials, which includes a PG 76-22 binder. Some cracks have developed out in the middle of the intersection, but this particular area consists of only a 2-inch overlay of 12.5 mm polymer-modified asphalt mix.”
Barker continued, “As a result of the success of the Fort Gay project, we have since constructed nine additional PMA projects throughout the state. None of them were intersection-only projects like Fort Gay, but all of them included problem intersections and/or slow moving heavy traffic lanes. Tough economical times and the cost of PMA may limit the number of projects that we construct in the future, but we at least now have a tool for dealing with extreme heavy traffic roads.”
Jeff Rutherford of Marathon Petroleum Company, the supplier of the PG 76-22 binder for the intersection project, is very pleased with the performance of the pavement. Rutherford said, “The Fort Gay intersection is a perfect example of how paying for durability up front can save state agencies money in the long run. All construction costs are continuing to escalate. Even with the initial cost of polymer modified asphalt being higher than conventional grades, states need to be looking at modified asphalts more now than ever as a long-term investment. We’re confident that no other construction material would have performed this well under the rigorous conditions of this intersection.”
|Bob Horan is a Regional Engineer for the Asphalt Institute.|