clack" sound of a train, but when the camera  shows the deck of the bridge behind and in front of the "train" you  can see that there are no tracks (the Hawthorne Bridge carries cars,  not trains). Tracks are only shown when the "train" makes an  emergency stop before Aaron climbs up the bridge. Even then, the  tracks are merely shiny strips of metal unevenly laid upon the  bridges metal grating, with no grooves for the wheels at all in the  surface.