THE BRONX - The Alexander Hamilton Bridge is undergoing the biggest single contract change in U.S. history with a budget of $407 million.

The project is expected to take four and a half years to complete. It will be done just in time for the bridge?s 50th anniversary.

Built in 1963, the steel on the massive structure is in need of refurbishing. Approximately 190,000 cars travel over the Hamilton Bridge every day.

Four travel lanes will stay open during construction with some overnight and weekend closures on connecting ramps. The project is expected to create more than 9,700 jobs.