I-25 (US 36 to 104th Avenue) Safety & Operations Improvements Study

About the Project

This project is in the study phase to evaluate improvements to traffic operations and safety on I-25 between US 36 and 104th Avenue. This stretch of I-25 has seen a steady increase in crashes since 2012 – most of these rear-end crashes that are typically associated with congestion.

Project Area

The project area is approximately a 5-mile segment of I-25 from US-36/I-270 to the south and 104th Avenue to the north. This urban corridor is located in Adams County and surrounded by the local communities of Sherrelwood, Welby, Federal Heights, Thornton and Northglenn.

Schedule & Important Dates

  • Open House Meeting: Wednesday, July 24, 2024
  • NEPA process: Spring 2024 - Spring 2026
  • Project Design: Spring 2024 - Summer 2026 (approximately)
  • Construction: Fall 2026 (tentative)

  • Improve transit and traffic operations and safety.
  • Minimize environmental, community, and climate impacts caused by the project, and provide the ability for CDOT's intercity Bustang service to serve RTD's Park-n-Ride at 88th Avenue in the future.
  • Wider shoulders along I-25 would improve safety by providing more space for emergency responders and drivers when needed.
  • Wider Express Lane buffer would allow more time for drivers to react to other drivers entering and exiting the Express Lanes.
  • Barrier separated Collector-Distributor (C/D) road system from westbound I-270 to 84th Avenue would improve northbound I-25 traffic flow. CD roads move vehicle-lane-changing away from high-speed traffic.
  • Moving transit loading and unloading operations to the center of I-25 would enhance transit operations.
  • A pedestrian overpass or underpass connecting the Mobility Hub in the center of I-25 to parking facilities along the highway would improve pedestrian safety.
  • Full 88th Avenue bridge replacement would accommodate the full width of the Thornton Park-n-Ride median transit station, standard shoulder and Express Lane buffer improvements, climbing lane and auxiliary lanes.
  • Adding auxiliary lanes in both directions between 84th Avenue and 104th Avenue would improve traffic flow between interchanges.
  • Providing a northbound climbing lane from 84th to 104th avenues would assist heavy trucks ascend steep grades.
  • Adding a fourth general-purpose lane on southbound I-25 between 84th Avenue and Thornton Parkway.
  • Buses servicing the Thornton Park-n-Ride cause safety and operational issues when weaving to and from the outer slip ramps to access the I-25 North Express Lanes.
  • Existing and growing traffic volumes combined with increasing population and employment growth will exceed capacity and increase travel demand by 2050.
  • The crash rate in this corridor has steadily increased since 2012 with the predominant crash type being rear-end collisions that are typically associated with congestion.