I-25 (US 36 to 104th Avenue) Safety 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

  • NEPA process: Spring 2024 - Spring 2026
  • Project Design: Spring 2024 - Summer 2026 (approximately)
  • Construction: Fall 2026 (tentative)

  • Improve transit and traffic operations and safety.
  • Improve the transit experience at the existing Thornton Park-n-Ride.
  • Maximize use of existing infrastructure.
  • Minimize impacts to residents and neighboring communities.
  • Improve bicycle and pedestrian connections.
  • Wider shoulders along I-25 will provide space for drivers to maneuver to avoid crashes and provide a safe space for law enforcement and emergency vehicles to operate.
  • Wider Express Lane buffer will allow more time for drivers to react to other drivers entering and exiting the Express Lanes unexpectedly.
  • Barrier separated Collector-Distributor (C/D) road system from westbound I-270 to 84th Avenue to improve northbound I-25 traffic flow and eliminate weaving movements. 
  • Moving transit loading and unloading operations to the center of I-25 will enhance transit operations.
  • A pedestrian overpass or underpass connecting the Mobility Hub in the center of I-25 to parking facilities along the highway will improve pedestrian safety.
  • Full 88th Avenue bridge replacement will 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 will improve traffic flow between interchanges.
  • Providing a northbound climbing lane from 84th Ave to 104th Avenue will assist heavy trucks ascend steep grades while improve traffic operations and safety.
  • Realigning Niver Creek Trails will connect to Thornton Park-n-Ride median transit station, 88th Avenue Bridge and RTD parking facilities.
  • 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.
  • I-25 is a barrier in the east-west movement for pedestrian and bicyclist connections.