The Colorado Department of Transportation broke ground Oct. 19 on its $806 million reconstruction of I-270 north of Denver, a six-mile interstate that opened between 1965 and 1970 and has never had a major upgrade. Kiewit is the contractor for the first phase. CDOT lists the contractors for Phases 2 and 3 as to be determined.
The project replaces 12 bridges, rebuilds the mainline between I-25 and I-70, adds one tolled express lane in each direction alongside two general-purpose lanes and rebuilds the Vasquez Boulevard interchange. CDOT’s schedule runs to 2033, ENR reported.
Kiewit’s I-270 Phase 1 starts with the worst bridges
Phase 1 runs through early 2030 and targets eight critical bridges, over the South Platte River, the Burlington Ditch, Brighton Boulevard and the Union Pacific and BNSF tracks, and 60th Avenue and another BNSF line. It also rebuilds the mainline from the South Platte to the start of the Vasquez ramps. Bridge reconstruction starts next spring.
The condition numbers explain the order. Over the past decade CDOT logged 160 planned maintenance activities and 65 emergency repairs on the corridor’s bridges, and six of the eight critical structures got preventive repairs in 2023. “There are places that feel precarious, there are joints that shake when you drive over them,” CDOT executive director Shoshana Lew told ENR.
Building it won’t be simple. The bridge work sits beside active Union Pacific and BNSF lines. River work needs temporary diversions, floodplain crane pads and possibly stream crossings, and new piers will go where the old ones stand so the channel keeps its hydraulic capacity. Westbound I-270 gets elevated between East 60th Avenue and the South Platte River Trail. More than 100,000 vehicles use the corridor daily, and CDOT plans overnight single-lane closures with no daytime mainline closures.
Funding the I-270 reconstruction
Money comes from state and federal sources, including about $170 million in federal funds. CDOT says express lane tolls, run by the Colorado Transportation Investment Office, could also help pay capital costs. The express lanes will be free for buses, motorcycles and carpools of three or more.
The project cleared its last federal hurdle Sept. 8, when FHWA published the final environmental impact statement and record of decision. That ended a six-year review.
Phases 2 and 3, from early 2030 through 2033, cover the rest of the mainline, the Vasquez interchange, the York Street and 56th Avenue bridges, the Vasquez bridge over Sand Creek and a new bike and pedestrian overpass. CDOT’s project page doesn’t show who will build them.
What to watch on the $806 million figure
That’s the open question. An $806 million total set in 2026 covers two phases that won’t be bid for years, at a time when construction input costs are up 11.9% from a year ago. Kiewit’s Phase 1 price will be the only hard number for a while. Colorado isn’t the only state pairing bridge replacement with toll lanes either; Georgia just picked a Ferrovial team for the I-285 East express lanes, though there the concession pays the state. When CDOT solicits Phases 2 and 3 around 2030, the bids will show whether $806 million still holds.