Life-cycle cost comparison of duplex stainless, weathering and carbon steel composite highway bridges

Durable highway bridges are required to achieve long service lives with minimal maintenance, particularly where access for inspection and repair is difficult or disruptive. While previous life-cycle cost (LCC) studies indicate that stainless steel can provide long-term economic benefits, the influence of bridge location, maintenance constraints and extended service lives remains insufficiently defined. This paper presents a comparative LCC assessment of a typical highway bridge with main girders fabricated in painted carbon steel, weathering steel and duplex stainless steel. Construction and maintenance costs are evaluated over service lives of 60 years and 120 years for four representative locations using updated UK-based cost and deterioration data. The results show that although duplex stainless steel bridges have higher initial construction costs, these can be offset over the service life by eliminating periodic steelwork repainting. This is particularly the case for bridges spanning over a railway, for which the cost associated with having to close the rail network for maintenance is particularly high. Weathering steel was found to be the most cost-effective solution where environmental conditions permit; however, its use is generally considered unsuitable for coastal environments or where exposure to de-icing salts occurs.