Diverging Diamond Interchange coming to Johnstown as part of the I-25 North Express Lanes Project

News Release

September 30, 2022 - Starting Oct. 3, 2022, CDOT will reopen the Colorado Highway 60 and I-25 interchange, and traffic will follow a single lane Diverging Diamond Interchange traffic pattern.

Weld County — By Monday, Oct. 3, 2022, the Colorado Department of Transportation and the I-25 North Express Lanes Project will reopen the Colorado Highway 60 and I-25 interchange, and traffic will follow a single lane Diverging Diamond Interchange (DDI) traffic pattern. 

The CO 60 and I-25 interchange will be closed no longer than 21 days so crews can safely realign the roadway from a standard interchange into the new DDI configuration.

When the interchange is complete, which is expected in mid-2023, there will be two lanes in each direction with a 10-foot-wide sidewalk, and upgraded landscaping and aesthetics. Upon reopening the interchange in early October, CO 60 over I-25 will be in a one lane in each direction DDI configuration to finish landscaping, irrigation and concrete work. Motorists are encouraged to use caution after the interchange reopens, as the traffic pattern will be significantly different and construction vehicles will be parked in the closed lanes (shown in red shading below). 

Diverging Diamon interchange I-25 North Express Lanes project map

“Diverging Diamond Interchanges are newer to interchange design and construction, but they provide significant safety and traffic flow benefits to areas with heavy directional traffic volumes, like the CO 60 and I-25 interchange,” said I-25 North Express Lanes Project Director Abra Geissler.

When driving a DDI, motorists proceed through a traffic signal upon entering the interchange and simply follow their lane to the opposite side of the roadway. Drivers needing to access I-25 from CO 60 will turn left at the on-ramp without having to stop again or wait for oncoming traffic to pass. Through traffic proceeds to a second traffic signal and follows the lane back to the customary side of the road. 

In addition, left-turn movements, which are a typical challenge with standard interchanges, are eliminated with a DDI, which minimizes T-bone type accidents. 

Drivers can view the video below on how to drive a DDI for more detailed information:

Diverging Diamond Interchange Video on Youtube

Additional benefits of a Diverging Diamond Interchange:

  • Reduces delays using a two-phase signal as opposed to a traditional four or six-phase signal. 
  • Requires fewer lanes but can handle more traffic capacity. 
  • Reduces conflict points at intersections. 
  • Improves pedestrian crossing safety with easier access to medians. 
  • Increases left-turn capacity. 
  • Eliminates wrong-way entry to ramps. 
  • Costs less than a typical free-flow interchange utilizing single directional flyover ramps. 

Please visit www.codot.gov/projects/north-i-25, for the most current travel updates. The I-25 North Express Lanes Project: Berthoud to Johnstown section will increase highway capacity by adding an Express Lane in each direction, rebuild interchanges, replace aging bridges, straighten highway curves to improve safety, make major utility and drainage improvements, and add carpool and transit facilities. During construction on the I-25 North Express Lanes Project, motorists should expect speed reductions to 65 mph, minor lane shifts, temporary concrete barriers and median bridge work. Motorists should also expect delays during the scheduled work hours. Construction on the Berthoud to Johnstown segment is expected to be complete in early 2024.

Project Contact Information

  • Project hotline: 720-593-1996
  • Project email – [email protected]
  • Project webpage - www.codot.gov/projects/north-i-25
  • Sign up for weekly project updates by logging onto the project web site and filling out the right-side form to “Subscribe to Project Updates.”