Bridges are the most important and most expensive elements of a road system. In spite of their importance, bridges form only a small proportion of a road system. Hong Kong has a relatively large number of bridges, but comprise only about 12% of the highway. The relative cost of bridges varies according to conditions, but is always many times the cost of ordinary carriageway. Hong Kong experience indicates that bridges cost, area for area, at least ten times as much as ordinary carriageway. Being so costly, bridges should clearly be fully serviceable for as high a proportion of their operational lives as possible. Maintenance should be required only infrequently, and should be cheap and easy to carry out. This paper discusses how design considerations can help to keep a bridge serviceable at minimum cost throughout its operational life. Some practical recommendations for low-maintenance design are given. (A) For the covering abstract see IRRD 882313.