The bridge is part of the North Metro Rail Line project, which is an 18.5 mile electric commuter rail system that will connect Denver’s Union Station with many of the city’s northern suburbs. Ten miles of the track have been completed so far, along with six of the train line’s eight stations.

Though construction of the Skyway Bridge will extend into 2017, one of the most difficult phases of the project has already been completed. A stretch of bridge runs in between the properties of an oil refinery and a large wastewater treatment plant, which provided little space for a crane to maneuver. 

The contractor Ralph L. Wadsworth Construction Company (RLW) rented the Grove GHC75 for the project from Colorado-based Honnen Equipment.

Lee Adams, construction manager for RLW, said that the maneuverability of the GHC75, along with its compact footprint, was crucial in completing construction. Adjacent (pre-existing) railroad tracks and a water-filled canal constrained space at one point on the job site, and on another, a retaining wall and fence flanked the skyway’s path.  

Adams said: “There was a very narrow alleyway to work with in between the two properties—it was a tight space that offered little more than the width of the train tracks themselves. There wouldn’t have been room for a standard, outrigger-equipped hydraulic crane. The GHC75 gave us the capacity we needed in a frame that was small and agile enough to traverse the narrow job site.”

The 118ft 1 in telescoping boom of the GHC75 combined with the crane’s ability to travel over rough terrain with its crawler tracks, performed some challenging pick-and-carry lifts.

“First we had to drive the crane over a railroad crossing and down beneath power lines to get it in position for the lifts,” Adams said. “Then we needed to pick up a load, boom down and navigate beneath the power lines without a hitch to place the load.”

The GHC75 lifted 9USt concrete gang forms to a height of 40ft, which enabled workers to bolt the forms together in an interlocking formation to construct the elevated bridge. The crane also hoisted 16USt rebar cages to heights of 72ft and released concrete on top of pier caps using a bucket system. 

Overall construction of the North Metro Rail Line began in October of 2015, and is on track for completion in fall of 2017.