An old wood-piling bridge in southern Maine is shutting down for a year to be replaced with a new span. The Sewall’s Bridge over the York River in York is closing on Tuesday. The new bridge will replicate the features of the existing bridge, with 13 pier structures and a 30-foot navigational channel for marine traffic. It will be about 250 feet long and cost about $3.4 million to build. During construction, traffic will be detoured about four miles to cross the river.