VAA Virginia Asphalt Spring/Summer 2021

18 SPRING/SUMMER 2021 Excellent and a CCI of 70–89 as good. Only one small section less than one mile long on the southbound side has a rating barely in the poor category (59), while 5 of the 15 sections still have ratings in the excellent category. As numerous research projects have shown, smooth pavements typically last longer. VDOT considers interstate ride quality to be excellent when the IRI is less than 60 in/mi. Despite the thin application, the placement contractors improved initial ride quality (i.e., 2008) by 18–35 percent over the original surface, with final surface IRI values ranging between 40 and 50 in/mi. Today, this smoothness continues with 2020 IRI values ranging from 46 to 76 in/mi and an average IRI of 56. Still in the excellent ride category! What Can We Learn? While real estate is all about “location, location, location,” pave- ment preservation is all about “timing, timing, timing” with the proper application. This project application represented a proactive departure from VDOT’s traditional overlay or “mill and fill” approach by intervening with an effective preservation treatment just before end-of-life indicators had developed. By VDOT’s CCI criteria, the existing pavement in 2007 was still in good condition and did not need a more traditional pavement maintenance treatment. Working from a structurally sound existing platform facilitated the placement of an extremely safe and smooth new wearing course that would effectively seal and preserve a substan- tial in-place investment. Today we have methods that make THMACO even more attractive as a preservation treatment. Alternative materials, such as high- performance tacks and newer paver systems, allow placement of these treatments with or without a true spray bar paver. While THMACO will not completely replace the more traditional pavement preservation treatments (i.e., thin surface seals, crack sealing, etc.), clearly this project proves it is a great tool when used correctly. In a letter to VDOT management in 2009, Michael Sprinkel, Associate Director with the Virginia Transportation Research Council (VTRC), summarized it this way, “…We can see no reason to be anything but optimistic about the prospects for the THMACO system for preserving high-priority pavements in Virginia.” Moving Forward So why haven’t we see more THMACO as a preservation treatment in Virginia? One reason is the overwhelming systemic issues surrounding the lack of appropriate funding levels for pavement maintenance in the past. Today $400M to $450M is programmed to be spent each year on pavement maintenance paving. These projects are spread over 120,000 lane miles—the third-largest state-maintained system in the US. And while a significant annual I-95 THMACO March 2009 Near Rte. 631 Overpass THMACO EXCEEDS EXPECTATIONS This project and others show that VDOT is willing to pursue methods to appropriately spend available funds in a prudent and effective manner. △ continued from page 17