Per the Wikipedia article that is linked to, under the disadvantages section, “Weathering steel is sensitive to humid subtropical climates. In such environments, it is possible that the protective patina may not stabilize but instead continue to corrode. The same thing can happen in environments laden with sea salt.” Paint will help, but not prevent the eventual decay of the structure. Sing steel in such a location was a poor choice the first time around, and will be proven to be a poor choice on the replacement bridge, unless costly and time consuming maintenance is performed at regular intervals (repainting being the biggest). Although it is nice for historical purposes to have the new bridge be built the same as the old one, al all concrete bridge would have been much better suited to the environment and will cost much less to maintain in the long run.