Reprinted from DCC at Work May 2015
The Sergeant Ralph Bridge at 5th Canadian Division Support Base Gagetown (formerly known as Canadian Forces Base Gagetown) is one of the most frequently travelled thoroughfares on the entire base. Troops and tanks on their way to the base’s massive range and training area, which covers approximately one eighth of New Brunswick, travel across the bridge pretty much every day.
The specifications of the Sgt Ralph Bridge had been more than satisfactory, up until recently when the Canadian Armed Forces acquired Leopard 2A4 tanks for the Canadian Army. Simply put, the Leopard 2A4 tank is a much heavier armoured battle tank with an optimal combination of firepower, protection, mobility and controllability. In other words, the new Leopard 2A4 tank at more than 67 tons is too heavy to cross the Sgt Ralph Bridge, which was never built to withstand the weight of such a heavy vehicle.
Whereas military engineers would have normally been the ones to dismantle and construct the new bridge, operational requirements did not allow for that to happen, so DCC has been working diligently with contractors to complete the job. Base personnel continue to be briefed on the progress of the project and so far everything is on time and on target.
“Up until now, this whole project has existed on paper so I am quite excited to see the crews disassemble the old bridge and the new bridge get launched,” says Nathan Stewart, DCC Coordinator, Construction Services.
“When you talk about engineering everyone thinks of bridges. It’s the stereotypical thing you think of. So the fact I’m working on a bridge capable of supporting these massive tanks, it doesn’t get any better than that.” One of the more unusual aspects of the bridge replacement is the way it is being done. Unlike other bridge construction methods, where workers are suspended over the bridge continuously building it in place using equipment that can be invasive to nearby land, water and sanitation systems, the Sgt Ralph Bridge is being built in a far more efficient, less disruptive way.
The process, known as an Incremental Bridge Launch, has been used by military engineers for more than a century. Although it is a tried and true bridge building method, it is still rather unique for non-military type bridges. The process is safer, less disruptive, less invasive, more cost-efficient and greener. With this method, bridges such as the Sgt Ralph Bridge are built on site, adjacent to the new bridge span, and then nudged into place an inch at a time, using massive industrial rollers.
The bridge launch is of course the final phase of a much longer design and site preparation process, which involves reinforcing the new abutment to hold a longer, wider bridge. The new bridge is 10m wide and 60m long, significantly larger than the old bridge.
In the spirit of environmental stewardship, the base provided the rock used to reinforce the new bridge abutment by blasting rock from an existing quarry on base property. That allowed the project team to save the client time and money by sourcing the rock internally.
The new Sgt Ralph Bridge is expected to be finished in late fall 2015.
From: DCC Newsletter May 2015
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