An employee of Balfour Beatty was partway up a 12-foot A-frame ladder, working with a crew to put up steel canopies on a rail corridor expansion. A tack weld broke on the steel post that was being used to push a canopy up into position. The post struck the employee's ladder, causing him to fall about 5 feet. He hit his head in falling, suffering a possible concussion; he also suffered a fractured wrist and a cut on the neck from the post.