I-66/Route 15 Interchange Reconstruction

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Prince William County, Virginia

RDA served as the Lead Designer in providing professional engineering services while LANE served as the Design-Builder/Lead Contractor on this Design-Build project for the Virginia Department of Transportation.

This project reconstructed the Interstate 66 (I-66)/Route 15 (James Madison Highway) interchange located in Prince William County, Virginia, to relieve congestion, enhance public safety, improve operations, bolster capacity, and accommodate forecasted traffic demand in the project area. RDA redesigned the reconstructed interchange as a Diverging Diamond Interchange (DDI)—the first of its kind in the region—to best accommodate the projected traffic volumes as well as critical pedestrian movements in the interchange area. An update to the Interchange Modification Report through extensive analysis by RDA validated an alternate interchange design that would best accommodate traffic demand, reduce the project footprint and environmental impacts, improve constructability and shorten overall construction duration when compared to previously considered alternatives while reducing overall project cost resulted in selection of the DDI.

The project also encompassed widening U.S. Route 15, widening VA Route 55 (John Marshall Highway/Washington Street), construction of a new service road, and replacement of northbound and southbound bridges carrying Route 15 over I-66 in a DDI configuration.

• Survey
• Data collection, studies and/or analyses (traffic, environmental, noise, etc.)
• Developing and completing the design
• Acquiring the necessary environmental permits
• Acquiring rights of way
• Coordinating and performing, or causing to be performed, required utility relocations, additions, and adjustments
• Roadway construction
• Milling and overlaying of existing pavement
• Bridge demolition and bridge construction
• Guardrail/barrier
• Retaining walls
• Sound barrier walls
• Landscaping
• Signs, sign structures, and foundations
• Traffic signals and modifications/Temporary Traffic signals/New Traffic Signals
• Lighting

Project Type

Interchange Reconstruction





Roadway Design


Hydraulic & Hydrologic Analysis

Public Involvement/Relations

Quality Assurance & Quality Control

Signal Plans

Signage & Marking Plans

Stormdrain & SWM

Utility Relocation & Coordination



2018 DBIA Design Build Project of the Year

 2018 VTCA Transportation Engineering Awards – Design Build Winner

2017 HCCA Excellence in Infrastructure