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I-66 and Route 15 Interchange Reconstruction

Constructing a new Diverging Diamond Interchange in Prince William County

Project Photos

Project at a Glance

Begin Date
Sept. 2015

Est Completion Date
Completed Aug. 2017

$59 million

Lane Construction Corp.

Prince William

Northern Virginia

Christiana Briganti-Dunn, P.E., CCM

Note: A ribbon-cutting was held Tuesday, Aug. 22, 2017.

View larger image of DDI

Latest information

UPDATE: All three lanes of the diverging-diamond interchange's (DDI) configuration have opened!

Learn about the DDI

Diverging-diamond interchanges (DDI) 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 reduce “red light” time for motorists.


Simulation of I-66 and Route 15 DDI

About the project

» Meetings were held Dec. 7 and 13, 2016, to discuss the opening of the DDI. View the meeting presentation online.

As part of this DDI, the project included constructing:

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


In May 2014, the Commonwealth Transportation Board warded a $36 million contract to Lane Construction Corp. of Chantilly to design and build DDI on Route 15 at I-66 to relieve congestion, enhance public safety, operations and capacity, and accommodate forecasted traffic demand in the area.

The Virginia Department of Transportation (VDOT) completed its first two DDIs in Louisa and Roanoke. Two more are under construction in Blacksburg and Stafford.

Estimated costs

Preliminary engineering: $3 million
Right of way acquisition and relocation assistance: $8 million
Design / Build contract (Final design, utility relocation and construction), contingency and VDOT oversight: $48 million
Total: $59 million


"Pardon our dust" meeting presentation (August 2015) || Revised Environmental Assessment (June 2015) and appendices || Information meeting (October 2014) || FHWA video - Diverging Diamond Interchange || Displays: Overall project, traffic flow, peak hour volumes 2036 || Comparison table - DDI vs. flyover  || Traffic operations - DDI vs. SDR || Public hearing brochure, comment summary (March 2013) || Information meeting brochure (March 2012)
Project Numbers
UPC: 100566 || State: (FO) 0066-076-074, P101, R201, C501 || Federal: IM-066-1 (341)

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Page last modified: Jan. 17, 2018