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Under Construction

I-66 and Route 15 Interchange Reconstruction

Constructing a new interchange in Prince William County

Project at a Glance

Begin Date
September 2015

Est Completion Date
Fall 2017

$59 million

Lane Construction Corp.

Prince William

Northern Virginia

Christiana Briganti-Dunn, P.E., CCM
Bill Atkins, CCM

About the Project

On May 14, 2014 the CTB awarded a $36 million contract to Lane Construction Corp. of Chantilly to design and build a diverging-diamond interchange (DDI) on U.S. 15 at I-66 to relieve congestion, enhance public safety, operations and capacity, and accommodate forecasted traffic demand in the area.

Diverging-diamond interchanges shift vehicles to the opposite side of the road and eliminate left turns that cross into oncoming traffic, improving safety. Traffic signals at each end of the interchange feature only two phases, reducing “red light” time for motorists and enhancing mobility. VDOT recently completed its first DDI on U.S. 15 where it crosses Interstate 64 at Zion Crossroads in Louisa County and has two more in the works in Roanoke and Blacksburg.

As part of this diverging-diamond interchange, the project will include constructing:

• Two longer bridges to carry U.S. 15 over I-66 with two crossover intersections;
• Ramp improvements (including a spur ramp to ease traffic flow from westbound I-66 to northbound U.S. 15 to westbound Heathcote Boulevard);
• Improvements on U.S. 15 from just north of the railroad tracks to just south of Heathcote Boulevard;
• Wider intersections on U.S. 15 at Heathcote Boulevard and Route 55, adding turn lanes to both; and
• A 10-foot-wide shared-use path on the east side of U.S. 15 for pedestrians and bicyclists.

The project also includes improvements to the Rte.15 intersections at Heathcote Boulevard and Route 55, and a shared-use path along the eastern side of Rte. 15.

Preliminary designs for the project included a Semi-Directional Ramp concept (See 2013 project brochure). When the project was advertised in September 2013, Design-Build teams had the option to offer alternate designs that address the project’s purpose and need. The concept proposed by Lane Construction/Rinker Design Associates is the Diverging-Diamond interchange.  

Video Simulation - Morning Peak Period

Video Simulation - Afternoon Peak Period


Project cost

Preliminary Engineering: $3 million
Right of Way acquisition and Relocation Assistance: $8 million
Design/Build Contract (Final Design, Utility Relocation & Construction), Contingency and VDOT oversight: $48 million
Total: $59 million

This project is being financed with federal and state funds. Costs are subject to change.

Anticipated Schedule

  • Public hearing on preliminary design - Spring 2013
  • Advertise project (Request for Proposals) - Sept. 24, 2013
  • Commonwealth Transportation Board project award - May 14, 2014
  • Citizen Information Meeting - Oct. 29, 2014
  • End of comment period - Nov. 17, 2014
  • Final Design - Winter 2014
  • Right-of-way acquisition - Winter 2014
  • Begin construction - September 2015
  • Complete construction - Fall 2017


Pardon our dust meeting presentation (Aug. 2015)
Revised Environmental Assessment (June 2015) and Appendices: 
    Appendix I - 2013 Environmental Assessment
Appendix II - U.S Dept. of Agriculture, Natural Resources Conservation Service Farmland     Conservation Impact Rating for Corridor Type Projects (Form NRCS-CPA-106)
    Appendix III - 2014 Final Design Noise Analysis

Information meeting (Oct. 2014)
    Presentation, brochure and insert
    FHWA Video - Diverging Diamond Interchange
    Comments and responses executive summary and detailed summary

PIM =Exhibits: Overall Project, Traffic Flow, and Peak Hour Volumes 2036
Comparison Table - DDI vs. Fly-over, and Traffic Operations - DDI vs. SDR

Contract Award (May 2014)
Public hearing brochure, comment summary (March 2013) 
Information meeting brochure (March 2012)
UPC: 100566
State Project: (FO) 0066-076-074, P101, R201, C501
Federal Project: IM-066-1 (341)

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Page last modified: June 13, 2016