Construction Overview

The longest construction zone in the state, the I-25 South Gap work zone stretches 18 miles between Monument and Castle Rock.

The project is split into three geographic regions:

  • North: Castle Rock to Tomah Road
  • South: Greenland Road to Monument
  • Middle: Tomah Road to Greenland Road

Splitting up the project allowed construction to begin on one section, while design was finalized on another. This means construction could begin much sooner than anticipated. Scroll down to learn about traffic impacts in each section. The project is expected to be completed in 2022.

Glare Mitigation on Frontage Roads

CDOT and contractor partner, Kraemer North America, took steps to improve safety along the frontage roads during construction of the I-25 South Gap project. During the month of February 2019, weather permitting, crews installed vehicle headlight glare mitigation. Along the frontage road at Tomah and Territorial roads, concrete barrier with headlight glare screen mounted on top was installed. Along the frontage road at Crystal Valley Parkway and Bell Mountain Road, fencing with headlight glare slats, which act similarly to window blinds, was installed. The goal is to shade vehicle headlight glare from motorists on local roads facing the highway.

Where crews are working – in the northern and southern sections of the project – the interstate speed limit is 65 mph. Speed limits along frontage roads between Castle Rock and Larkspur are 45 mph. In areas where flaggers are present, speeds are 40 mph. Remember – fines are doubled in work zones.

North: Castle Rock to Tomah Road

Construction on the I-25 South Gap began in September 2018 in this 5-mile section. Throughout construction, crews will shift traffic three times:

  • Traffic Shift No. 1
    • Crews have already shifted traffic to the outside shoulders to work on the I-25 median, where the new Express Lanes and wider shoulders will be built.
  • Traffic Shift No. 2
    • Then, traffic will move to the newly constructed area, so crews can work on the outside lanes. This is expected in spring 2019.
  • Traffic Shift No. 3
    • Finally, traffic will move back to the outside, so crews can place the final overlay and striping.

South: Greenland Road to Monument

Crews are placing a barrier to protect a 7-mile work zone between Greenland Road and Monument. Here’s what to expect from construction between Monument and Greenland Road:

Monument to County Line Road: Similar to work on the northern end of the project, construction in this area will begin in the median, with traffic shifted to the outside shoulders. Then, the configuration will switch. Construction includes widening, earthwork, asphalt paving, storm sewer pipes, a new wildlife crossing and new median barrier and retaining walls. View illustration.

County Line Road to Greenland Road: Work in this area will begin on the outside shoulders, so traffic will be shifted to the middle. Construction includes a new wildlife crossing, widening, storm sewer pipes and median barrier and retaining walls. View illustration.

Greenland Road Crossover: The Greenland Road interchange will be completely rebuilt and include a new wildlife crossing. For crews to safely work, a major traffic shift is necessary. Northbound I-25 traffic will crossover and ride head-to-head on southbound I-25. Traffic will be separated by a temporary concrete barrier. Then, both driving directions will switch to the northbound side. View illustration.

Monument Hill Road: To build a new wildlife crossing, crews will need to close Monument Hill Road for up to four months, starting later in 2019.

Temporary pavement will allow crews to maintain two driving lanes in each direction during peak travel times, though some extended ramp closures at Greenland and County Line roads will be necessary.

Middle: Tomah Road to Greenland Road

This section is the most complex. Construction on this 6-mile section will include bridge replacements at Upper Lake Gulch, Spruce Mountain Road and Plum Creek and two new wildlife underpasses.

Design on this section is continuing, and work is expected to begin in 2019. Watch this page for more details on construction.

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