A roadway construction site with an overpass over a highway.

Transform I-66 Outside the Beltway Project


Our Client’s Challenge

Providing access to the District of Columbia, Interstate 66 (I-66) is a key east-west interstate highway in Northern Virginia. The corridor outside of the Capital Beltway (I-495) includes general-purpose lanes, high-occupancy vehicle (HOV) lanes, heavy rail transit (Metrorail’s Orange Line), local and regional bus service, and bicycle and pedestrian facilities.

Traffic jams along the I-66 corridor are intensifying, particularly in the eastern section where peak congestion now grips the highway for four to five hours daily in both directions. Experts predict that by 2040, traffic volume could surge by 10% to 66%. This spike will likely extend peak congestion times to eight to 10 hours daily each way, severely disrupting personal cars, freight haulers, emergency services, and bus transit operations. Meanwhile, ridership on the Orange Line is anticipated to surpass its capacity, further complicating regional travel demands.

Our Client's Solution

The Virginia Department of Transportation (VDOT) selected I-66 Express Mobility Partners (I-66 EMP) to design, build, operate, and maintain the renovated interstate. I-66 EMP will recoup its investment over the life of the 50-year contract via managed lane toll revenue. With a total value of $3.6 billion, the project is one of the largest public-private partnership (P3) projects underway in the U.S.

The concession agreement required I-66 EMP to pay $500 million upfront to fund corridor enhancements recommended by the Northern Virginia Transportation Authority. The private partner must also pay a net present value of $800 million for transit services and $350 million for additional corridor improvements, such as highway expansions and pedestrian projects, over 50 years.

Private sector financing improves heavy civil roadway building, and the project includes $579 million in direct investment for other regional multimodal projects. Multimodal enhancements include mixed-use paths, Virginia Railway Express Manassas Line enhancements, and new bus and maintenance facilities. By 2066, transportation and operational enhancements along the I-66 corridor will cost an additional $800 million.

Construction Services

I-66 EMP selected Gannett Fleming to be their technical advisor and provide independent construction oversight of the design-builder, including:

  • Quality oversight inspection.
  • Independent testing of on- and off-site construction materials and comparing those results to the design-build quality assurance/quality control (QA/QC) plan.
  • Periodic review of materials and testing records, evaluating materials testing rates for compliance with VDOT frequency requirements.

Additional responsibilities included performing QA/QC audits of the design-build quality processes for compliance with governing specifications, standards, laws, and contract requirements. Each constructed project asset was maintained and provided an asset classification, which was then “inventoried” as part of an ESRI®-compatible, geographic information system (GIS)-based mapping of all project assets for future maintenance and identification purposes.


The Transform I-66 Outside the Beltway project involved renovating and expanding 22.5 miles of express lanes from the Capital Beltway (I-495) to the western terminus in Gainesville, Va. Expansion of the tolled lanes required various intelligent transportation system (ITS) devices connected via fiber optic cabling. Construction included miles of duct bank construction, conduit, and fiber optic installation. Gannett Fleming provided preliminary design for tolling, ITS, and communications, including:

  • Dynamic message signs, closed-circuit television (CCTV) cameras, vehicle detectors, toll gantries, and hundreds of ITS junction boxes.
  • Fiber optic communications infrastructure to support the ITS and tolling system.
  • Directional drilling and boring for ITS conduits.
  • Plans to maintain the existing ITS systems during construction.

Construction included two new I-66 express lanes and three reconstructed general-purpose lanes with dedicated access ramps and extra median space for future transit infrastructure. An advanced dynamic-tolling system monitors existing vehicle volume and adjusts rates in real-time, managing demand and keeping traffic moving.


I-66 EMP needed to effectively coordinate and manage the myriad project components, including the electrical work, ITS devices, bridge construction, paving, noise walls, and drainage. These parts all had different timelines and were in various stages of development. GeoDecisions — Gannett Fleming’s GIS, data management, and technology division — built a web-based, mobile-friendly, interactive project dashboard and map that allowed field users to leverage the Esri ArcGIS Collector to enter status information for real-time project updates on each construction asset phase.

This up-to-date stream of information was organized and displayed on the ArcGIS Online web map and dashboard, providing construction analytics on project progress and summarizing construction data. These tools provided real-time updates to VDOT, I-66 EMP, and the construction team. In addition, the platform’s visualization and data analysis functions enabled stakeholders to identify issues, manage risks, inform decision-making, and facilitate clear communication. GeoDecisions used key technology, including:

  • Esri ArcGIS Dashboards.
  • Esri ArcGIS Experience Builder.
  • Esri ArcGIS Pro.
  • Python.
  • Esri ArcGIS Online.

GeoDecisions added more than 200 data layers, with multiple variations at each level, such as dirt movement, stormwater, noise abatement, drainage molding, line painting, and signage. In some cases, certain project elements — 60 total bridges, pavement, drainage, and retaining walls — directly impacted each other, making tracking these layers particularly critical. Using the dashboard, stakeholders readily tracked the progress of each project element, making it easier to plan subsequent activities.

Key Features

  • 22.5 miles of new express lanes alongside three regular lanes on I-66 from I-495 to University Boulevard in Gainesville.
  • 63 renovated or newly constructed bridges, including 11 at the I-495 interchange and 13 at the Route 28 interchange.
  • New and improved bus service and transit routes.
  • New and expanded park-and-ride lots provide convenient access to the express lanes and more than 4,000 new park-and-ride spaces.
  • 18 miles of new bike and pedestrian trails, including shared-use trails along I-66 that integrate with local trails, and new crossings of I-66 to improve and expand bicycle and pedestrian routes.


  • More reliable and faster trips on I-66 due to dynamically tolled express lanes — available to solo drivers choosing to pay a toll and free to vehicles with three or more people.
  • Safety and capacity enhancements at key interchanges.
  • Expanded commuter bus service to help meet the growing demand for public transit options while decreasing road congestion.

Awards & Recognition

  • Awards. This web part is hidden.


Virginia Department of Transportation (VDOT)


Fairfax and Prince William Counties, Va.


Technical Advisor and Construction Services

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