PERPETUAL PAVEMENT BY DESIGN: EXCELLENCE IN VIRGINIA of three general-purpose lanes and one auxiliary lane with fullwidth shoulders in each direction. Anyone traveling through this area of Northern Virginia can attest to the extremely high traffic volumes. Estimated 2023 traffic volumes in this section of I-66 can exceed 200,000 vehicles per day, with around 7% of those vehicles being trucks. From a pavement loading perspective, this equates to nearly 4.0 million Equivalent Single Axle Loads (ESAL) per year. For these reasons alone, designing a long-lasting pavement structure is critical not only to the long-term performance of the pavement but also to ensure minimal disruption to the users of this heavily traveled roadway. David Shiells, VDOT Northern Virginia District Materials Engineer and pavement design engineer of record, states, “I-66 is a major commuter and commercial artery in Northern Virginia, so it was extremely important that the pavement design requires minimal maintenance. This pavement structure will only require resurfacing on a periodic basis, and the use of a high-quality surface mix will ensure that disruption to the traveling public is minimized.” VDOT began developing a design from the subgrade up. Further supporting the need for a robust pavement design, this area is plagued with poor soils, with an average subgrade modulus of 3,000 psi. The pavement structure was designed to consist of 12 inches of a highly drainable open-graded aggregate (VDOT #2/#3) wrapped in geotextile drainage fabric and connected to a UD-4 edge drain for all new construction and widening sections. Asphalt layers consist of 14 inches of Base (VDOT BM-25.0A), 2 inches of intermediate (SMA 12.5 used for traffic during construction) and 1.5 inches of final surface (SMA 9.5). Both the intermediate and surface layers utilized a polymer modified 64E-22 (PG76-22). As noted, perpetual pavement concepts represent a forward-thinking approach to road construction, focusing on long-term durability and minimal maintenance. By leveraging advanced design principles, high-quality materials, and strategic maintenance practices, perpetual pavements offer a sustainable and cost-effective solution for roadway infrastructure needs. While the initial investment and technical requirements may be higher, the long-term benefits in terms of reduced lifecycle costs, enhanced performance, and sustainability make it an attractive option for highway and urban road projects. The APA and the Virginia Asphalt Association (VAA) proudly recognize VDOT and the I-66 Outside the Beltway Express Lanes project with this Perpetual Pavement by Design award. VAASPHALT.ORG 21
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