abdullahi halakhe, thank you so much. baltimore after being hit by a container ship, it's emerged that most bridges in the united states do not have impact protection that could prevent similar incidents. our us news partner cbs news says it's found thatjust over a third of the more than 4,000 bridges that allow ships to pass under them are vulnerable. bridges built after 1991 have increased protection, but the rules didn't require upgrades for older ones. for more on the situation, i spoke to dan su, the associate professor of civil engineering at embry—riddle aeronatuical university. it can be said that accidents happen quickly and recovery is so slow. talk to us about the barriers facing people before try to begin rebuilding. i think there are some barriers, i wouldn't even say barriers, but some issues that need to be taken care of before rebuilding. first of all, we have to get to the bottom of this, the experts need to do forensic study, to understand what happened. we know there's some power issue that may have cau