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Elk City's Diverging Diamond Interchange atI-40& SH-6

Oklahoma's first DDI

I-40 and SH-6 Interchange in Elk City now OPEN in final DDI configuration marking a state first

Drivers should be aware of the new traffic configuration at the I-40 and SH-6/Main St. interchange in Elk City with the opening of the state's first Diverging Diamond Interchange:

  • SH-6 traffic is now in its final DDI configuration. Drivers should use caution as they enter the reconfigured interchange for the first few times.
  • Motorists need to pay additional attention to all traffic control devices, including the new traffic signals, pavement markings and signage as well as follow the speed limit.
  • This area remains an active construction zone through winter 2020. Motorists are urged to use caution as traffic adjusts to the new configuration.
  • Drivers on I-40 lanes and ramps as well as SH-6 lanes may experience intermittent closures as final work continues.The project is set to complete in winter 2020.

Drivers should begin thinking about how to safely navigate the DDI. Here are several safety tips to consider before driving through the new interchange:

  • As you approach the interchange, drive for the conditions by following the speed limit. Pay attention to traffic control devices and pavement markings.
  • As you enter the interchange, follow the signs, signals and pavement markings to cross through the intersection at the first set of traffic lights. Traffic will appear as if on a one-way street as it crosses above I-40.
  • Vehicles continuing straight on SH-6 after crossing I-40 simply proceed through a second set of traffic lights.
  • All left turns onto the interstate are free flow, meaning vehicles do not have to stop to access the ramp.

In2015, the existing twin bridges onSH-6overI-40were deemed structurallydeficient, meaning the roadway is safe for travel but in dire need of repair. Starting in May 2019, ODOTbegan a project todemolish the existingSH-6 bridges over I-40and replace them with a new type of interchange - a Diverging Diamond Interchange.

Watch: A step-by-stepvideo of how to use a Diverging Diamond Interchange

Watch: See what I-40and SH-6 will look like once the DDIis completed

Courtesy: CEC Corporation

(Edit: Plans are to also place stop lights on the ramps.)

Elk City is a growing community. Sitting along the famous "Mother Road" Route 66, the town experiences high traffic volumes on both I-40and SH-6. The last survey completed in 2017shows 8,500vehicles travel SH-6 on average per day.

About the Project

Construction of Oklahoma's first Diverging Diamond Interchangebeganin May2019atI-40andSH-6in Elk City. The innovative design offers aprovensolution for improving traffic flow and safety at the interchange.

  • Reconstruct SH-6and I-40 on-and-off-ramps.
  • Construction is estimated to cost $16 million.
  • Construction is expected to last about a year, with a substantial completion date of summer2020, weather permitting.

About Diverging Diamond Interchanges

The definition of a Diverging Diamond Interchange: Two directions of traffic on the non-freewayroad cross to the opposite sides of the bridge at the freeway.

  • Currently, there are just under 100DDIsnationwide.
  • The first was constructed in Springfield, MO in 2009.
  • DDIscreate safer, less congested intersections.
  • DDIsallow for fewer conflict (accident) points.
  • DDIsgive drivers better sight distance at turns.
  • DDIspedestrian crossings are shorter.
  • DDIsaim to eliminate the left turn and thereby increase safety
  • DDIsgive "free-flowing" or simple left and right-handturns from all directions.
  • Wrong way entry to ramps become extremely difficult.

Traffic Impact During the Project

  • I-40and SH-6will remain open to the traveling public.
  • I-40will be narrowed to one lane in each direction at times throughout the project.
  • I-40will have minimal ramp closures at SH-6.
  • Crews will have minimal nighttime closures of I-40and SH-6to demolish the existing bridges.

Stay updated

During the project, drivers should use the following sources to stay connected about changing traffic conditions:

  • ODOT'straffic advisories athttp://ow.ly/3GMU30nwdjE
  • ODOT'sTwitter and Facebookaccounts
  • ODOT'sapp on the Apple and Android App Stores
Last Modified on Oct 21, 2020
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