This paper was presented at the `Strategic investments in structures' session. An important large bridge structure carrying traffic under the main line CPR rail lines in Sudbury, Ontario, was severely deteriorated due to the expansive effects of the alkali-silica reactive aggregates used in the original concrete mix and the effects of freeze-thaw disintegration and reinforcement corrosion. The primary objective for the rehabilitation of this structure was to provide a cost effective solution to extend the safe service life for a further 20 years. From 1993 to 1995, detailed investigations and a feasibility strudy were conducted to compare three options for the structure, i.e., replacement of the structure to the existing geometry, replacement of the structure to accommodate additional traffic lanes and pedestrian movement and, rehabilitation of the exisisting structure. It was concluded that the rehabilitation scheme was the most cost effective and sensible solution to meet the objective. Detailed specifications and contract deocuments were prepared in 1996-7 followed by construction in 1998 for a total construction cost of $3.53 million. This paper discusses the investigative procedures used to determine the condition of the structure, the overall findings and the recommended solution to attain the desired objective to increase the service life. A brief outline of the technical specifications and construction restrictions is provided followed by a review of the construction procedures and techniques employed by the contractor. (A)
Abstract