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