Workers are constructing temporary supports to lay concrete for an arch bridge on the Naples Causeway on Route 302. The new bridge will replace the 60-year-old swing bridge that was cemented shut last fall. Craig Hurd, resident engineer for the Maine Department of Transportation, said the project is on track for allowing traffic to shift onto the new bridge in the middle of May, so the shorter swing bridge can be removed and boats can travel between Long Lake and Brandy Pond by Memorial Day weekend.