Work Begins on McCaslin Diverging Diamond Interchange

March 26, 2014 - Metro Denver Colorado/CDOT Region 1 - BROOMFIELD – Work is starting on the US 36 Express Lanes Project’s Diverging Diamond Interchange (DDI), a traffic management design that enables free left turns at the ramp intersections. Part of Phase 2 of the project, the new DDI will replace the current McCaslin Boulevard intersection to extend the operational life of the interchange.

With a DDI, traffic is crossed to the opposite side of the road across an interchange, allowing vehicles to have unimpeded movements onto the freeway ramps. This reduces delays because the left-turn phase of the signal is eliminated, allowing for additional time for through traffic, which minimizes conflict points at intersections and increases left-turn capacity.

“Left-turn movements across traffic are typically a challenge at standard four-way interchanges but are completely eliminated with a DDI,” said CDOT Project Director Mark Gosselin.

In addition to the new traffic design, the interchange will also include a new pedestrian underpass in Superior, widening of the existing bridge, new bus loading stations and new aesthetic features including an arch on the bridge.

From April to August 2014, the following activities are scheduled for McCaslin Boulevard:

  • Barrier placement
  • Concrete removal
  • Roadway removal
  • Realigning traffic to the southbound side of McCaslin
  • Temporary sign installations
  • Asphalt paving

Currently, crews are continuing earthwork and temporary paving, as well as completing temporary pipe installation and right-of-way fencing. During the week of March 31, there will be single daytime and nighttime lane restrictions on McCaslin Boulevard from 8:30 a.m. to 3:30 p.m. and from 9 p.m. to 5:30 a.m. the next morning. The DDI will be complete in early 2016.

The US 36 Express Lanes Project is a multi-modal project that will build an express lane in each direction on US 36. The lanes will accommodate High Occupancy Vehicles (HOV), Bus Rapid Transit and tolled Single Occupancy Vehicles. In addition, the project will replace several bridges, build a commuter bikeway, add Bus Rapid Transit improvements, and install Intelligent Transportation Systems (ITS) for tolling, transit and traveler information, and incident management. Phase 1 is currently under construction from Federal Boulevard to 88th Street in Louisville/Superior and will open to the public in 2015. Phase 2 from 88th Street to Table Mesa Drive in Broomfield recently began construction and will open in 2016.

For more information about the project, please visit or our mobile website at To receive free email updates during the project, click on the cell phone icon in the upper right corner. You can then subscribe to a variety of lists including “US 36 Express Lanes Project.”