The new 12-mile West Rail Line opened in May, 2013 giving light rail passengers more access to the Denver metro area than ever before. The new line between Denver, Lakewood, and Golden, Colorado on the W line provides 11 new stations and 6 new Park-n-Rides. The crown jewel of the line is the 6th Avenue Arch Bridge. This ballasted light rail arch bridge carries double track service over the 6th Avenue Freeway and is the signature bridge of the West Corridor. The 280’ “basket-handle” arch is fabricated from high-strength, weathering steel. Known as a specialty steel that naturally “rusts” to a dark purple-brown color and forms a protective oxide coating, this steel eliminates the need and expense of painting, now or in the future. The arch was designed to span the entire 6th Avenue Freeway.
The arch is part of a 5-span elevated structure. The two 81’ approach spans on each side of the arch are comprised of concrete bulb-T girders. The challenge was to erect the arch span over an existing freeway with minimal impacts to the traveling public.
Summit Engineering (Summit) developed an innovative, accelerated construction method that required a short duration closure of the freeway to completely construct the arch. Initially, the arch was fully assembled on-site near its final location. With all lanes of 6th Avenue closed on a Saturday morning, the fully-assembled arch was rolled across 6th Avenue. The transporters that guided the arch across the highway consisted of two 35’ transport platforms with 8 axles each. Both of the transport trailers contained hydraulic rams to keep the platforms level. The arch’s southern end traveled on guided rollers pushed by hydraulic rams, which were the main driving force. Fourteen hours later, the steel arch came to its final resting place spanning all lanes of 6th Avenue.
This was the first time in the United States that a basket-handle, tied arch was “rolled out” using this method. Thanks to the efforts of Summit’s engineers, the “roll out” procedure went off without a hitch and the freeway was reopened ahead of schedule.
This was the first time in the United States that a basket-handle, tied arch was “rolled out” using this method. - Gregg A. Reese, PE, President, Summit Engineering Group
Gregg A. Reese, PE (Project Principal)