County Line Road reopens after 100-day closure in Douglas County

County Line Road is moving traffic again between University Boulevard and Broadway, giving Douglas County drivers back one of the corridor’s main east-west links after a 100-day closure that forced detours onto C-470 and rerouted daily trips to University and Broadway.

The reopening on Thursday, April 16, marked a major milestone in the County Line Road Widening and Reconstruction Project, but it did not end the disruption entirely. Douglas County said crews still had striping work to finish between Clarkson Street and University Boulevard, and drivers should expect mobile lane closures, traffic shifts and intermittent single-lane travel as the next phase advances.

County officials said the closure, which began Tuesday, Jan. 6, was needed so crews could safely import, move and place dirt at Lee Gulch and remove the roadway dip there. The fill effort was substantial: the county said the work involved 30,000 cubic yards of dirt, an amount it compared to filling 40,000 washing machines, along with 1,500 feet of Denver Water pipe, more than 3,000 feet of concrete wall and 3,000 feet of concrete storm pipe.

The county said the project stayed on time and on budget during the closure, a key point for commuters, deliveries and emergency access in the County Line corridor. Business access remained open throughout the shutdown, with University Boulevard serving businesses east of the closure and Broadway serving businesses west of it. Residential access to Clarkson Street stayed in place via Dry Creek Road and County Line Road.

The wider project, being built by JHL Constructors, is a roughly $30 million effort that Douglas County has been developing since 2019 with final design work, right-of-way acquisition and utility relocation planning. It will add one travel lane in each direction, install a new traffic signal at Clarkson Street and County Line Road, add sidewalks, and include mill and overlay work on the Littleton segment between Phillips Avenue and Broadway.

Centennial has described County Line Road as the final segment in the corridor that still needed widening from two to four through lanes for full reconstruction. That means the April 16 reopening should improve access right away, but the biggest travel-time gains are still ahead, when the remaining work is complete and the corridor can function with its added capacity. Douglas County has said completion is expected in September 2027.

The roadway project also ties into broader mobility work in south metro Denver. Littleton’s County Line Trail Connections project is designed to improve safety and connectivity for pedestrians and bicyclists along County Line Road and the High Line Canal Trail, with coordination among Douglas County, the High Line Canal Conservancy, South Suburban Parks and Recreation, the Highlands Ranch Metro District and Denver Water.