Construction Overview

The I-25 South Gap work zone stretched 18 miles between Monument and Castle Rock. The project was split into three geographic regions:

  • North: Castle Rock to Sky View Lane (Tomah Road)
  • Middle: Sky View Lane (Tomah Road) to Greenland Road
  • South: Greenland Road to Monument

Splitting up the project allowed construction to begin on one section, while design was finalized on another. Scroll down to learn the construction elements in each section.

North: Castle Rock to Sky View Lane (Tomah Road)

This section received an Express Lane, wider shoulders and new pavement in both directions.

South: Greenland Road to Monument

Here’s what to expect from construction between Monument and Greenland Road:

Monument to County Line Road: Construction included widening, earthwork, asphalt paving, storm sewer pipes, a new wildlife crossing, median barrier and retaining walls. View construction phasing illustration.

County Line Road to Greenland Road: Construction included a new wildlife crossing, widening, storm sewer pipes, median barrier and retaining walls. In 2019, CDOT added funding to replace the County Line Road bridge. View construction phasing illustration.

Greenland Road: The Greenland Road interchange was completely rebuilt from a single lane box culvert, which was originally built in 1948, to a two lane underpass. Construction in this area also included a new wildlife crossing. View construction phasing illustration.

Monument Hill Frontage Road: Construction of a new wildlife crossing.

County Line Road bridge: Reconstruction of the County Line Road bridge. The bridge doubled in size to accommodate one through-lane in each direction, a turn-lane in each direction and wider shoulders.  Learn more

Middle: Tomah Road to Greenland Road

This 6-mile section was the most complex. Construction included new Express Lanes, wider shoulders, a new wildlife underpass and bridge replacements at Upper Lake Gulch Road, Spruce Mountain Road and Plum Creek.

Download the middle section construction fact sheet.