Part of Hood Road is scheduled to close for about four months as the state replaces a 36-year-old bridge over Rocky River.Hood Road will be closed to traffic starting July 30 between The Plaza Extension and Robinson Church Road.Steel pilings were added in March 2002 to reinforce the bulkheads, the vertical walls underneath the bridge. That was a temporary solution. Now N.C. Department of Transportation has decided to replace the bridge rather than do temporary fixes, despite the bridges relative youth. The new bridge is expected to last at least 60 years, although there are no guarantees. Bridges are like people, said Garland Haywood, N.C. DOT bridge engineer. They age at different rates.The bridge is on a suburban two-lane road that serves as a cut-through between Robinson Church and Rocky River roads.Hood Road carries a relatively light traffic load. It had about 3,600 cars a day on average in 2008, the most recent count available, Haywood said.Yet the bridge has an efficiency rating of 11.5 (where 100 is the best score) on its most recent inspection in 2010. We have some rust on the beams, Haywood said. We have rust on the underside of the steel-plank floor. For a bridge that old, its not uncommon.Dane Construction of Mooresville won a $602,000 contract to remove the bridge and its supports, put up a new one, install guard rails and build up the shoulders of the road on the approaches to the bridge.Utilities have already been moved in the construction area. Construction is scheduled to be complete by Nov. 26.Detours around the project will be posted, from Hood Road to Plaza Road Extension to Harris Boulevard to Robinson Church Road back to Hood Road. The old bridge is about 27 feet wide and 45 feet long. The new bridge will be 30 feet wide, 60 feet long and made of concrete with an asphalt surface. The height of the bridge will remain the same, but the additional length is expected to allow more space for water to flow over the river banks during heavy rains.Planners expect to do hydraulic modeling to help assure that increased water flow under the bridge would not be too much to handle for areas downstream.We have to look out for flooding issues, Haywood said. We want to know that we havent restricted water or allowed too much.