C+S July 2020 Vol. 6 Issue 7 (web)

Reinforced Earth Walls Support Northern Virginia’s First Diverging-Diamond Interchange Reinforced Earth | www.reinforcedearth.com

About 40 miles west of Washing- ton, DC along the I-66 corridor, PrinceWilliam County, Virginia has been experiencing rapid growth. In Haymarket, VDOT implemented Northern Virginia's first Diverging- Diamond Interchange (DDI) to alleviate congestion and accom- modate future growth in the area. The project included the construc- tion of two parallel bridges for RT 15 to cross I-66. Both bridges used Reinforced Earth® MSE walls at the pile-supported abutments, for a total of four walls. The square con- crete facing panels were cast with a dry-stack stone architectural finish, then painted in the field to match the cast-in-place traffic bar- rier on the bridge deck. The design-build team included Rinker Design Associates as the lead designer, with Lane Construc- tion as the general contractor.

Parallel bridges carry traffic in the opposite direction, crossing over beyond the abutment on each side.

The DDI was chosen for its innovative method of improving capacity and safety. The design moves traffic over the bridge to the opposite side of the road. The traffic light system reduces wait time, and the crossing pattern eliminates left turns into oncoming traffic. According to VDOT, the system has twice the capacity of a traditional diamond interchange. In 2018, the project won the DBIA Design Build Project of the Year as well as the VTCA Transporta- tion Engineering Award for design-build.

The southwest MSE wall abutment shown, with precast concrete facing to match the bridge parapet.



july 2020

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