I recall several years ago a ship damaged the Chesapeake Bay Bridge by plowing through it and taking out several sections. I have always wondered how they fixed the piling that supports the structure. Since both ends of the damaged portion of the bridge remained, the pilings in the damaged area would have to be driven in the same location as the ones sheared off in the accident. Can they do that? Are the damaged ends squared up and a new piling driven in the same spot? Or can they just put forms on the damaged end and pour concrete and extend the existing ones? How do they affix the rebar, and also, once salt water contacts the damaged portion of the concrete piling, isn't there a problem with the chloride in the fracture area a potential problem in the future? Or, can they just vary the locations of the replacement pilings to avoid the damaged ones and put the bridge back together with a bit of variation in the span length? It's an amazing bridge, I've never been able to drive over it however.