SAN RAFAEL, Calif. (KGO) -- Repairs on the Richmond-San Rafael Bridge started Friday night around 9 PM after concrete fell on to the lower level on the eastbound side, backing up traffic for two hours.Caltrans said the reason why the piece of concrete fell today is apparently not the same reason as last time this happened.Richmond Mayor Tom Butt said, "The concrete part of it is the real problem. It's not necessarily the steel part, it's the concrete part. It apparently is basically reaching the end of its useful life."The Mayor of Richmond is an architect on the side and says this bridge need to be replaced. Tony Tavares, Caltrans Director for district 4, says that's the long term plan."Developing a study for a bridge replacement and this year we will request the fund from MTC Data to do that study."Tavares mentioned that unlike in February when a piece of concrete fell on a vehicle. Friday's incident is not the same."They were doing demolition work on one of the sliding plate expansion joints and some of the concrete fell on that barrier system."There were no injures but some Richmond resident are planning to avoid the bridge"I'm worried about something dropping on me or maybe something happening on the bridge itself," said resident Don Cota.Ironically, for April fools, Richmond's mayor joked about the bridge closing on April 15."The Richmond bridge, more stuff is falling off and they are gonna have to shut it down forever. I hope that didn't come true I meant it as a joke."It was a joke or a prediction of the future.Caltrans did mentioned over the phone that the bridge is safe for drivers and they will continue repair work.