Old Skeena Bridge Rehabilitation

Client: The BC Ministry of Transportation

McElhanney was retained to provide engineering services to rehabilitate the Old Skeena Bridge (#0473) in Terrace, BC, which was originally opened to the public in 1925. The original bridge was constructed at a different location than the current position, which was constructed in 1953. The new bridge reused some of the spans from the 1925 construction. The bridge had gone through some renovations in the past, notably the deck was changed from cast in place concrete to timber and more recently to an open grated steel deck in 2001. Foundation for the superstructure was provided by mass concrete abutments and piers. The bridge was restricted to a maximum 4 tonne load limit.

The objective of this assignment was to rehabilitate select bridge elements to allow the client's inspection truck to safely access the bridge while maintaining the existing 4 tonne GVW load posting and provide a 25 year service life. Specific professional services that were provided included:

• visual inspection to supplement previous inspection,
• structural evaluation for live loads,
• detailed rehabilitation designs,
• preparation of tender documents and project supervision during construction (summer of ‘06).

Our bridge engineers free climbed the superstructure for the visual inspection to keep access costs to a minimum. The final rehabilitation design established which specific members required replacement to achieve the project objective and included bearing replacements for all the expansion bearings. Our design focused on constructability, including specifying jacking procedures for bearing and member replacement.