The 9/11 memorial closed Wednesday morning when a beam crashed through a window at 4 World Trade, raining shards of glass and construction debris on passersby. The beam was being lifted by a crane at the building, when a gust of wind sent it swinging into a large glass panel. Luckily, nobody was hurt, but the construction team is exerting caution. “We have suspended steel lifts pending an investigation, are inspecting the entire façade of the building, and are reviewing protocols for evaluating weather conditions,” said John Gallagher, a spokesman for Tishman Construction. A day earlier, a worker was impaled by a piece of steel at the same site, but survived the injury.