Phase-I was initiated in 1980, and consisted of field inspections of 52 highway bridges. In 1988, the FHWA convened a forum where more than 130 federal and state government and industry representatives met to discuss their experiences with the performances of weathering steel in bridges. In 1993, AISI began Phase-III of this project. This included revisiting the 52 bridges that were initially inspected in 1980 as part of Phase-I, and following 13 more years of exposure. As a result, over 2,300 bridges in the United States have been built with this material over the last 30 years.
Studies show that using weathering steel reduces both initial and life cycle costs.
Current highway legislation in the United States mandates the consideration of life-cycle cost analysis in the highway materials selection process. The primary conclusion of this report confirms that uncoated weathering steel bridges are all performing well throughout the United States and Puerto Rico, with the exception of metropolitan Detroit. It suspected that material problems found in Michigan are caused by the amount and frequency of salts used in inclement weather, the chemical composition of these deicing salts, or a combination of these factors. The result of this study demonstrated that uncoated weathering steel bridges designed and detailed in accordance with the recommendations outlined in the FHWA Technical Advisory will perform well. The study focused on 63 bridges in 11 states and the commonwealth of Puerto Rico that have been in service between 18 and 30 years.