RS&H has acquired the Colorado Springs-based architecture and planning firm HB&A! Learn more. 

Interstate 25/Colorado State Highway 402 Interchange Design-Build

Project Details

Client/Owner

Colorado Department of Transportation

Focus Areas & Services

Location

Loveland, CO

Reconstructing I-25: a massive undertaking

The design-build project aimed at reconstructing 14 miles of Interstate 25 (I-25), including overhauling three full interchanges. The Colorado State Highway 402 (CO 402) interchange was critical, acting as the main gateway from I-25 to the City of Loveland and enduring substantial truck traffic.

The challenge of CO 402 interchange

The existing CO 402 interchange presented a unique set of challenges. It was a tight diamond configuration with I-25 passing over it and a frontage road on the east side, immediately adjacent to the interchange. This compact layout was further complicated by substandard horizontal and vertical curves on I-25, which raised significant safety concerns.

Safety and traffic operation improvements

The project required a complete reconstruction of the interchange to enhance safety by standardizing the curves of I-25 and improving traffic flow at the three intersections involving the southbound ramps, northbound ramps, and the frontage road. The timeline was constrained by a strict 120-day closure of CO 402, with no closures permitted for I-25 or the ramp connections from CO 402.

Innovative solution by RS&H

In a display of innovative thinking, RS&H proposed completely flipping the interchange, having CO 402 pass over I-25. This strategic change, combined with the adaptable nature of roundabout geometry, allowed the team to shift the roundabouts and the crossroad southward. This shift facilitated the construction of a perpendicular bridge crossing over I-25 that could be built offline, thus avoiding a full closure of I-25.

The revised design enabled the construction of a single-span bridge, which was completed swiftly, reopening CO 402 well within the 120-day limit. Implementing free-flowing roundabouts further enhanced traffic operations, even with the challenging constraints of the interchange and frontage road configurations.

Explore Exciting Career Opportunities with Us!

Related Projects

The Davidson River Village Connector is a new location roadway in the City of Brevard connecting US 64/276 and US 64.

Transportation

RS&H designed a new roundabout for the Hardscrabble Green Loop, a segment of the City’s Roswell Loop.

Transportation

RS&H is providing on-call services for toll operations on the Triangle Expressway, Monroe Expressway, I-77 Express Lanes, and future tolled and managed lanes projects.

Transportation