Construction crews begin rail welding at Kalamath Street crossing

During the week of Oct. 6, construction crews with RTD began rail welding work at the Kalamath Street crossing as part of the agency’s Downtown Rail Reconstruction Project (DRRP).

Launched in May 2024, the DRRP is the first large-scale reconstruction of RTD’s oldest light rail infrastructure. The work ensures the long-term reliability of the downtown rail network, much of which has been in continuous service since light rail operations began in 1994.

Part of a multi-year, $152 million project to reconstruct miles of light rail track in downtown Denver, this year’s work focuses on replacing aging rail and reconstructing key track intersections at the Kalamath Street and Colfax Avenue crossings. Work began Sept. 2 and is scheduled to continue through Nov. 27. Throughout construction, crews are coordinating activities to maintain alternate transit connections and minimize service disruptions.

Click here to watch video highlighting the rail welding process at Kalamath Street

As of Oct. 16, crews had completed 62 of 81 thermite welds at the site. Welding teams and RTD inspectors documented quality and process information for each weld to ensure long-term durability.

Using a process known as thermite welding, crews fuse long sections of rail by igniting a mixture of aluminum powder and iron oxide to create molten steel, which bonds the rails together. Once cooled, the joints are ground to match the rail’s profile, resulting in a smooth, continuous track.

"Continuously welded rail has a benefit to customers by significantly reducing the amount of noise and vibration in the ride,” said Matt Druffel, RTD Construction Manager for Capital Programs.

The Kalamath Street work remains on schedule, with Phase 3 now roughly 37% complete. The milestone highlights RTD’s continued progress in modernizing its downtown light rail infrastructure for the next generation of customers.

For the latest project information, including maps, timelines and detours, visit rtd-denver.com/railproject. Weekly status reports are posted on Fridays and include photos, maps and illustrations. Questions can be directed to [email protected] or by calling the project hotline at 720-902-8817. Customers can also find details about Service Changes and sign up for Service Alerts to stay informed about construction-related impacts.