I rewatched the video and with regards to traffic on the bridge - you can see clearly the headlights of vehicles going in both directions. From what I can tell there were no vehicles on the bridge when it got hit. If they truly got a message sent and the bridge closed down in the 4-5 minutes leading up to the strike, then that is excellent work by USCG and MD DOT or whoever was responsible for it. Bridge appeared empty of traffic at time of impact.