Cost Comparison of Timber, Steel, and Prestressed Concrete Bridges

Abstract

This study was undertaken to investigate the economics of timber bridge superstructures versus traditional steel/concrete and prestressed concrete alternatives in the short‐span range of 20 to 60 ft (6.1–18.3 m). Only superstructure costs were considered because substructure and abutment costs are highly site‐specific. A lack of definitive data regarding service lives and maintenance costs precluded a life‐cycle cost study; thus, only initial costs were compared. Representative superstructure designs were obtained for timber, steel/concrete, and prestressed concrete bridges at 20‐, 40‐, and 60‐ft spans. Five to six northern New England general contractors performed cost estimates on these designs. Also, nine timber bridge designs, three at each span length, received cost estimates from three timber bridge suppliers. Results from general contractors indicated that timber was cost competitive with steel/concrete and was less expensive than prestressed concrete. Results from timber bridge suppliers showed more impressive distinct initial cost advantages for timber over both steel/concrete and prestressed concrete. The study indicated the initial cost effectiveness of modern, short‐span timber bridges in northern New England.