Iliff Avenue Corridor Construction Project

The Iliff Avenue corridor construction project is now underway. This $25.64 million project will take 21 months to complete and greatly improve this important two-mile thoroughfare in Arapahoe County between South Parker Road and Quebec Street. Work will begin at South Parker Road and will move west toward Quebec Street. Project completion is anticipated late Spring 2023. Concrete Express, Inc. is the contractor for this project. 

View the most recent work schedule and travel impacts

A full closure of southbound Syracuse Way from eastbound Iliff Avenue will be in place from through late June. With the closure, crews will perform underground drainage replacements, reconstruct the median and sidewalks and fully repave the Syracuse Way and Iliff Avenue intersection. Detours are in place. Motorists will either detour south on Quebec Street to Harvard Avenue and turn east to access Syracuse Way or continue east on Iliff Avenue to Trenton Way, turn south. Continue south to Harvard Avenue, turn west to access Syracuse Way.

Northbound Syracuse Way traffic to eastbound Iliff Avenue will remain open.

Crews will reduce Trenton Way to one lane in each direction at Iliff Avenue to perform underground utility and roadway work. The lane reduction will be in place through early June. 

Intermittent full closure of the Cherry Creek Trail continues. A detour is in place. Trail user detour from the trail to Cherry Creek Drive at Iliff Avenue. Go east on Iliff Avenue to Valentia Street and use the crosswalk to the south side of Iliff Avenue. Go west to join the trail on the east side of the bridge. Always use signalized pedestrian crossings to cross Iliff Avenue.

Throughout the corridor project, travelers can expect daytime and night traffic impacts as the project progresses. Intermittent lane closures should be expected. Minor impacts to bicycle and pedestrian access will be required. Access to transit stops will be maintained throughout construction. Check out the updated RTD bus stop closures

For inquiries or to receive project and construction updates please email the project team at

As part of the project, two dilapidated buildings at the corner of Parker Road and Iliff Avenue were demolished in the first week of November 2021. This property, which included the old Barn Store, was purchased by the County in December of 2020 for $1.76M to make improvements to corridor. Check out pictures of the demolition.

Project Background

A Corridor Study was completed in February 2015 for the Iliff Avenue Corridor between Quebec Street and Parker Road. This study evaluated and identified improvements to transportation system mobility, safety, and reliability along the corridor. Water quality enhancements and storm water conveyance needs associated with the roadway infrastructure improvements were also evaluated and recommended. 

Planned Improvements

Following the Corridor Study, Arapahoe County secured Federal funding for the design and construction of the recommended operational improvements along the corridor, some of which include:

  • Four-lane Iliff Avenue corridor with acceleration/deceleration lanes
  • Intersection modification
  • Bike lanes and sidewalks between Rosemary Street and Dayton Way; multiuse path at east and west ends of corridor
  • Transit stop enhancements
  • Sidewalk/multi-use paths/crosswalk improvements
  • Transit supportive programs
  • Traffic signal progression optimization
  • Signal detection/video monitoring
  • Signal communication/equipment upgrades

For more details regarding the plans, see the list of corridor improvements.  

Iliff Project Design Opens in new window

View a scalable, detailed PDF of the map

Project History & Schedule  

  • Beginning of design phase: May 2016 
  • Data gathering: Spring/Summer 2016 
  • Preliminary design: Summer/Fall 2016 
  • Final design and environmental clearance: 2017-2018 
  • Right-of-Way Plans and Acquisitions: 2019-2021 
  • Construction: July 2021 to late Spring 2023  

Submit Comments and Questions

We appreciate your interest in the Iliff Avenue Corridor Construction Project. Comments and questions are welcome at any time and can be submitted by calling 720-239-2283 or email: