I recently found out that the twinspan that was damaged during Katrina has to be checked and joints rewelded EVERY NIGHT! Gives me the heebies. It's a very long temporary bridge made of metal, and the stress of the day causes bolts to break free. That being said, it is a very necessary bridge and it will take a few years to complete repairs. Not to mention that the thing was erected in about a month. Fairly impressive.