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I-64 Interchange at Route 15, Zion Crossroads

Construction of a diverging diamond interchange (DDI)

Project at a Glance

Begin Date
Design work October 2012; construction June 2013

Est Completion Date
April 15, 2014

$6.883 million design-build contract

Lengths and Limits
0.49 mile

Design: Parsons Corporation / Construction: Corman Construction Inc.



Greg Cooley

New Traffic Pattern Now in Effect

VDOT conducted an overnight traffic switch Feb. 21 on the Zion Crossroads diverging diamond interchange (DDI) project.

When driving the new DDI configuration, motorists will proceed through a traffic signal at the interchange and follow their lane to the opposite side of the roadway. Vehicles needing to access Interstate 64 will merge left using an on-ramp without having to stop or wait for oncoming traffic to pass. Through traffic proceeds to a second traffic signal and follows their lane back to the right side of the road.

Construction activity on the DDI will continue through mid-April. Until the project is finished, Route 15 will be reduced to one lane in each direction; once open, Route 15 will be returned to four lanes.

Project Purpose

The purpose of this project is to improve the I-64 interchange on Route 15 at Zion Crossroads (exit 136).

In 2007, VDOT identified a need to increase the capacity of the I-64 off-ramps at the Route 15 interchange, which—combined with a forecasted increase of traffic due to the area’s commercial growth—prompted a study of potential interchange options. 

In addition to the diverging diamond interchange (DDI), VDOT analyzed the construction of a single-point urban interchange, improvements to the existing diamond interchange, and a no-build alternative. The clover-leaf interchange was not included based on the amount of land acquisition it would require. 

Overall, the diverging diamond interchange produced the best results based on today’s traffic volumes as well as those projected for 2035.

What is Proposed?

VDOT proposes to reconstruct the 0.49-mile stretch where Route 15 meets I-64 (exit 136) as a diverging diamond interchange (DDI). By briefly shifting vehicles to the opposite side of the road, this innovative interchange design eliminates traditional left turns that must cross over oncoming traffic. The DDI improves safety by reducing the number of spots where vehicles could collide and can handle more than 600 left-turn movements per hour, twice the capacity of a conventional interchange.

This is the first diverging diamond interchange in Virginia. Two others are in the design phase in the Roanoke area.

The diverging diamond interchange is new to the U.S. Though the design originally appeared in the 1970s in Versailles, France, America’s first DDI was built in 2009 in Springfield, Missouri. There are now approximately 30 DDIs in operation nationwide.



Flyer on DDI operation and background:
   8.5x11" size, one-sided Adobe Acrobat PDF (142 KB)
   8.5x5.5" size, two-sided, prints two per sheet Adobe Acrobat PDF (149 KB)

News release: Diverging Diamond Now Open on Rt. 15 at Zion Crossroads

News release: REMINDER: Traffic Switch at Zion Crossroads Feb. 21

News release: Diverging Diamond at Zion Crossroads Opening Feb. 21

News release: VDOT Plans for New Traffic Pattern at Zion Crossroads

News release: Zion Crossroads Construction Begins May 29

News release: Construction to Start at Zion Crossroads in May

YouTube video simulation of proposed interchange design

Diagram of proposed interchange design Adobe Acrobat PDF (321 KB)

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Page last modified: April 18, 2014