Enerpac Launches 3,420t Alaska Bridge Across 283m Canyon

Enerpac hydraulic systems have been used to launch the 3,420-tonne Juneau Creek Bridge across a 283-metre canyon in Alaska, completing the crossing over an eight-day operation.

The bridge, located at Cooper Landing on the Kenai Peninsula, stands 86 metres above the canyon and is now Alaska’s highest highway crossing. It also represents the state’s longest continuous-span bridge built in more than 40 years.

Rather than erect temporary supports within the canyon, Traylor Bros. constructed the complete steel girder bridge on one side and pushed the structure across using a custom Enerpac Bridge Launching System developed for KWH Constructors.

The system used four 100-tonne hydraulic cylinders with 3-metre strokes, positioned in pairs on two of the bridge’s five girders. Operating at a maximum pressure of 160 bar, the cylinders delivered a standard launching speed of 12 m/h and up to 18 m/h in fast mode.

A grip-push-grip sequence moved the bridge forward in 3-metre increments. Four 250-tonne clamping cylinders, operating at 700 bar, alternately gripped and released the girders while the launch cylinders extended and retracted.

The hydraulic power unit also integrated the systems used for launching, clamping, levelling and guiding the bridge.

Position sensors and pressure transducers on the launch cylinders fed information to a master controller, allowing operators to monitor cylinder position and load throughout the operation and run the system manually or automatically.

“By combining all the bridge launching actions in a single, integrated and containerised HPU we were able to accurately monitor and control the bridge launch at every stage,” said Justin Sieg, Launch Director at KWH Constructors.

The Juneau Creek Bridge forms a key part of the more than $500 million Cooper Landing Bypass project, which is intended to improve safety and traffic flow along a 16 km section of Alaska’s Sterling Highway.

The project is being managed by the Alaska Department of Transportation & Public Facilities in partnership with Traylor Bros. and Quality Asphalt Paving.