The New Brunswick Department of Transportation (NBDOT) has about 475 culvert type bridges constructed of galvanized corrugated steel pipe materials (soil-steel structures). Since 1987, about 25 % have been rehabilitated by installing a concrete invert. A further 8 % of these steel pipe bridges have been replaced. Completed project costs for both rehabilitation and replacement have been tracked and compared. The comparison shows that rehabilitation of soil-steel structures is much more cost effective than replacement and less difficult to undertake. Steel pipe rehabilitation is achieved by placing a structurally connected reinforced concrete layer on the deteriorated metal section. Usually this extends over the bottom half of the pipe. In addition, flow velocity and fish passage features are incorporated in the concrete invert as required by site conditions. A hybrid bridge structure with an extended service life is the result. The paper addresses the following aspects of NBDOT experience: (1) history and material durability problems, (2) bridge inspection and condition assessment, (3) rationale for rehabilitation, (4) the current rehabilitation program and (5) typical rehabilitation. For the covering abstract of this conference see ITRD number E216511. (Author/publisher).
Abstract