On May 23 of this year, a span of the Skagit River Bridge on I-5 in Washington collapsed. A tall truck struck the bridge, causing structural failure. This despite the fact that the bridge was judged safe in 2010. Similar bridges are found across the Pacific Northwest. Why, in Oregon alone there are 65 steel truss bridges that will one day require demolition. Portland’s Steel Bridge is one of the oldest, at 101 years old. Steel bridges service state highways, country roads, and city streets across the Beaver State. Regardless of whether these bridges collapse or are replaced, they will all require demolition at some point. And when demolition does occur, industrial demolition contractors will be called upon to take down these steel bridges safely and effectively, using some of the methods we outline below.
Best Practices for Selective Bridge Demolition
Outline Bridge Materials and Corresponding Demolition Methods. Taking down any enormous structure requires careful planning. Different techniques are required for different materials. Concrete, for instance, can be demolished using explosives, jackhammers, and bursting—a process that involves applying pressure or injecting chemicals to break apart concrete. Steel, on the other hand, must be dismantled through dismantling.
Dismantle Steel Through Sawing, Water Jetting, or Thermic Lance. Demolition contractors may use enormous saws and cranes to cut through and remove bridge steel. Oftentimes, demolition saws sport diamonds, which are harder than nearly all other materials on earth. Water jetting is similar, except that it uses extremely high pressures (50,000 PSI or more) to dismantle bridge materials. This approach minimizes fire hazard, dust accumulation, and damage to surrounding materials. A third method is thermic lancing, in which specialized torches melt through steel, cutting it into smaller chunks that can be hauled away later.
Sort and Salvage Materials. Once the bridge has been dismantled, its materials must be sorted into piles of similar substances, and then sold to salvaging firms or sent to landfills.
Industrial demolition contractors who dismantle steel bridges often specialize in scrap metal demolition. Steel is a lucrative salvage material, since it can be recycled repeatedly without losing its structural strength. Today’s bridges can be recycled into the bridges and buildings of the future.