Fifty years after careful planning and step-by-step construction opened the old Port Mann Bridge outside of Vancouver, B.C., those same building blueprints define its dismantling.

With a new 10-lane bridge partially opening in 2012 and steadily gaining momentum as crews wrap up construction on the widest cable-stayed bridge in the world, the focus has turned to removing the old Port Mann Bridge.

According to Transportation Investment Corporation, the group in charge of the Port Mann project, removing the 1964-opened bridge required a return to how it was built originally.

Crews dredged up the original blueprints for the arched steel bridge to dismantle the structure in the exact reverse order of how it was constructed. The teardown works from the middle out and even requires braces and stay towers similar to those use during original construction, reports Vancouver’s Journal of Commerce.

Crews must cut out the defining orange steel arches using thermal lances and then use cranes to drop the pieces to waiting barges. The steel is shipped off for recycling.

The in-water work offers up some other challenges, as explosives are required to remove those supporting pedestals. Crews will use bubble curtains to surround the blast area and the process starts with smaller blasts to scare away any marine wildlife in the area before the big explosions puncture the water.

While the final lanes of the new Port Mann Bridge get completed, crews will continue to dismantle the old bridge, with all remnants of the orange steel likely gone by summer 2015, erasing 50 years of British Columbia transportation history.

Tim Newcomb is Engineering News-Record’s Pacific Northwest contributor. He also writes for Popular Mechanics, Sports Illustrated and more. You can follow him on Twitter at @tdnewcomb or visit his website here.