Instructional Video of the Day: How to Build Skyscrapers Over Moving Trains

There are construction obstacles, and then there's building towering skyscrapers above the open-air tracks of the busiest passenger transportation facility in America.

That's what mega-developer Brookfield is trying to do on a block of the West 30s between 9th and Dyer Avenues, where it broke ground on the Manhattan West project last week. The company intends to develop two 60-story towers without interrupting train traffic, though a dozen tracks connecting Penn Station to the New Jersey tunnels run right through the site

How is this possible? With an ingenious decking system of interlocking concrete bridges, moved into place by giant machines.

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