CORROSION OF HIGHWAY BRIDGES: ECONOMIC IMPACT AND CONTROL METHODOLOGIES

This paper reports on results of research to determine the cost of corrosion with respect to reinforced concrete highway bridges. In 1998, 9% of conventional reinforced concrete bridges and 3% of prestressed concrete bridges in the United States were found to be structurally deficient. The overall area of structurally deficient bridges is 370 million sq ft, with these structural deficiencies largely attributable to corrosion. The annual direct cost of corrosion for highway bridges is estimated to be between $64.3 billion and $10.15 billion. Life-cycle analysis estimates indirect costs due to traffic delays and lost productivity at more than 10 times the direct costs of corrosion. Employing best maintenance practices is estimated to save 45% of the annual corrosion costs of a bridge deck reinforced with black steel. A significant portion of corrosion can be attributed to deicing salts. To avoid corrosion from the chloride, bridge designers should choose reinforcement resistant to corrosion, make the concrete less corrosive at specific chloride levels or prevent chlorides from reaching the steel surface by coating the reinforcement or providing physical barriers at the concrete surface. Surface barriers, cathodic protection and electrochemical chloride removal can reduce corrosion and extend service life for existing bridges. Summaries of costs and resulting life expectancy for these methods are provided. Increased funding and greater awareness of new construction materials and corrosion control methodologies should be utilized to extend bridge life expectancy.