1:56 am - Friday September 22, 2017

CDOT, City of Grand Junction Partner on State’s First Diverging Diamond Interchange

Traffic switch Monday to accommodate construction at I-70 and US 6/50
The Colorado Department of Transportation and the City of Grand Junction
have partnered to bring the state its first Diverging Diamond Interchange (DDI) – an innovative
interchange design that improves efficiency by eliminating some wait time for left-hand turn
movements. This project represents a partnership between CDOT and the City of Grand Junction to
improve safety and traffic flow on I-70 at Exit 26 (at US 6 & 50). The contractor began mobilizing
equipment to the area on July 8, and traffic impacts will begin this Monday, July 15 (see Traffic
Impacts, below).
The I-70 DDI is the first in the state—some 15-plus DDIs have been built in the US, the first being in
Springfield, MO. The I-70 DDI project, which will continue through November 2013, was designed by
the City of Grand Junction and is being constructed by CDOT.
A DDI eliminates traditional left-hand turns by crossing lanes and shifting drivers to the left side of
the road. This gives drivers direct access to a left-hand ramp to access the interstate without waiting
at a traffic signal. The lanes then shift drivers back to the right side.
Diverging Diamond Interchanges can carry much more traffic than conventional diamond
interchanges, and the capacity for left-turn movements is twice that of a conventional diamond.
Safety has been shown to increase at interchanges and intersections built as diverging diamonds.
The amount of crashes is reduced, as are the severity of crashes. The accidents that do occur are at
angles that eliminate the dangerous “T-bone” that can happen at a traditional signalized intersection.
The cost of the I-70 DDI is $4 million,* whereas other alternatives for interchange reconstruction are
between $10 and $15 million. Minimal right-of-way acquisition is required for this type of intersection.
“This is a first-of-a-kind project for us, and we are very excited to implement this DDI in an area
where traffic and commerce are growing rapidly,” CDOT Chief Engineer Tim Harris said. “This
“Taking Care To Get You There”
project represents a successful public-public partnership—and one that capitalizes on efficient and
effective use of tax-payers’ dollars.
TRAFFIC IMPACTS: Starting at 7 p.m., this Monday, July 15, motorists on US 6/US 50 will be
switched to the eastbound lanes, with a single lane in both directions (the turn lanes onto the I-70
ramps will remain). The speed limit will be reduced from 45 mph down to 35 mph. This traffic switch
will remain in place 24/7 until the work in the westbound lanes is completed—likely early September.
Then, all traffic will be switched onto the newly configured westbound lanes. The project is scheduled
for completion in late 2013.
The City also has an adjacent project underway at 22 Road (see below); CDOT and the City are
working together on the timing of these two projects at 22 Road and at the I-70 DDI to minimize
impacts to travel through this area.
CITY PROJECT – City of Grand Junction – 22 Road Improvements, March 2013 through August
2013: The City is realigning the 22 Road and US 6 intersection, moving it 500 feet west. This
lengthens the intersection spacing with the I-70 interchange ramps, which will improve traffic
efficiency and safety. A new connecting street will link Valley Court to 22 Road. Traffic will be able to
access US 6 via the signalized intersection at 22 Road, eliminating the need for left turns out of
Valley Court and improving safety.
PROJECT INFORMATION – Additional information on these two projects is available via the
following:
• Colorado Department of Transportation at
http://www.coloradodot.info/projects/i70exit26grandjunctionddi, call the project information line
at (970) 618-9805 or write to I70B@npri.co.
• City of Grand Junction at http://www.gjcity.org/PublicWorksProjectsPage.aspx, call Paul
Jagim at (970) 244-1542 or write to paulj@gjcity.org.
*CDOT’s DDI will be paid for, in part, with FASTER funds. Funding Advancements for Surface
Treatment and Economic Recovery was established by the Colorado General assembly via Senate
Bill 09-108 (www.coloradodot.info/projects/faster) to fund the repair or replacement of Colorado’s
poor-rated bridges and make safety improvements to Colorado’s key corridors

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