Crews working on Littleton's $21.4 million Santa Fe Drive and Mineral Avenue overhaul have reached the halfway mark, and the most jarring change for drivers is still ahead: every left-turn arrow at the intersection is going away for good. The project is reshaping the busiest and most dangerous crossing in the city, where roughly 90,000 vehicles pass through each day.
According to Denver7, Santa Fe Drive alone carries about 60,000 cars daily while Mineral Avenue handles roughly 30,000, and the City of Littleton has been working with the Colorado Department of Transportation to redesign how that traffic moves through the junction. Between 2021 and 2025, the intersection recorded 183 crashes, including 28 serious injuries and one death, making it the site of more collisions than any other intersection in Littleton, per the station's reporting. Left-turn movements were tied to the highest number of those incidents, according to Denver7's reporting, which cited city traffic official Matuszewski.
Why Left Turns Are Disappearing
Once construction wraps, drivers will no longer be able to turn left directly at Santa Fe and Mineral. Instead, the station reports that motorists will be rerouted through a quadrant road, a roundabout, and connecting side streets to complete those movements. Southbound Santa Fe drivers headed for Mineral, for instance, will turn left on Nichols Avenue, loop around a roundabout, head north on Flat River Parkway, then turn left onto Mineral Avenue, per the same account.
City officials broke ground on the project on November 19, 2025, building what amounts to the Denver metro area's first quadrant roadway interchange, according to the City of Littleton. Quadrant roadways are designed to pull left-turning traffic off the main intersection entirely, which frees up more green-light time for through traffic on the primary corridors.
The Payoff: Faster Commutes, Despite the Detours
The rerouted turns may add time to any single movement, but Denver7's reporting notes that traffic studies and simulations point to a dramatically faster system overall, with total travel time through the intersection expected to drop by up to 50 percent once the project is finished. The gains vary by direction and time of day. Westbound Mineral Avenue drivers could see evening peak-hour travel times fall by as much as 30 percent, while eastbound Mineral drivers might cut morning peak travel by up to 50 percent, the station reports. Northbound Santa Fe drivers are projected to save up to 15 percent during the morning rush, and southbound Santa Fe drivers could see evening rush-hour times drop by up to 50 percent as well.
The city is sharing videos explaining the new traffic pattern to help drivers adjust before the full configuration goes live, according to Denver7's reporting. Full completion is expected in 2027.
Regional Growth Is Driving the Redesign
The timing is no coincidence. The Denver Regional Council of Governments projects that traffic at Santa Fe and Mineral will climb from today's roughly 90,000 vehicles per day to approximately 115,000 by 2040, driven by continued development across Arapahoe, Douglas, and Jefferson counties, as detailed in a DRCOG support letter. The corridor is one of the primary arteries linking southern metro suburbs to Denver, and DRCOG's Metro Vision Regional Transportation Plan classifies South Santa Fe Drive, also known as US 85, as a major congested arterial where cutting down idling time is also seen as a way to help regional air quality.
The intersection isn't just a vehicle chokepoint. It sits beside RTD's Littleton/Mineral Light Rail Station and bus transfer facility, as well as the Mary Carter Greenway and South Platte River Trail network, both heavily used by cyclists and pedestrians, according to the same DRCOG letter. Nearby commercial growth is adding to the pressure: Littleton City Council approved 1st Street Farms, a $28 million Peyton Manning-backed restaurant and venue development, in the adjacent River Park zone this past June, as reported by CBS News.
How the City Is Paying for It
Littleton's $2.8 million share of the project, after federal grants and developer contributions, comes from 2021 Ballot Issue 3A, a 0.75 percentage point sales tax increase that voters approved by a 59% margin to address a backlog of municipal infrastructure needs, according to Patch. That measure marked the city's first municipal sales tax rate increase in half a century. The project also secured federal Highway Infrastructure Program grant funding through a FY 2025 Community Project Funding application backed by U.S. Representative Jason Crow and DRCOG, which reduced the direct cost to city taxpayers.
What Drivers Are Dealing With Right Now
In the meantime, the construction zone is already reshaping daily commutes. As of this month, Mineral Avenue west of Santa Fe Drive has been narrowed to a single lane in each direction, with permanent traffic signals removed and a 45-foot vehicle length restriction placed on right turns, according to the city's project update. The work is part of a broader push toward multi-modal upgrades in the area: Littleton finished Phase 1 of the adjacent Mineral Mobility East project this past spring, adding buffered bike lanes, upgraded pedestrian paths along the Mineral Avenue Trail, and improved High Line Canal Trail crossings leading toward Santa Fe Drive.
Just south of the construction zone, the Colorado Department of Transportation separately completed a $2.5 million repair on the southbound Santa Fe Drive flyover bridge to eastbound C-470 between February and July of this year, addressing bridge pier caps and columns near Pier 7. City officials continue to frame the quadrant road design as a lower-cost alternative to building a full grade-separated interchange, while acknowledging that commuters, light rail riders, and trail users will keep dealing with short-term detours until the project's expected 2027 completion.
