This paper describes the design, manufacture and construction of a buried precast, prestressed concrete arch, with a span length of 19.6 m (64.3 ft) and an overall length of 173 m (566ft), which carries highway traffic over railway tracks near Obed in Alberta, Canada. In design, a nonlinear finite element analysiswas undertaken to account for the interaction between the structure and surrounding soil, as the arch was subjected to back fill and highway loadings. This allowed the arch wall thicknesses to be reduced substantially when compared to the thicknesses used in conventional designs. The arch was erected over a Canadian National Rail main line without disturbing railway traffic. The structure was designed to provide Alberta Transportation and Utilities years of service, with maintenance costs lower than those normally associated with highway bridges.
