Idylwyld Drive Overpass at Ruth Street Rehabilitation
In 2013, the City of Saskatoon commissioned ISL to perform initial baseline testing and inspection of Idylwyld Drive Overpass to determine the extent of deterioration and offer recommendations for rehabilitation. After reviewing these recommendations, the City reengaged ISL in 2014 to conduct detailed testing and to design the rehabilitation.
Evaluating Every Option
To ensure the most effective strategy was chosen, ISL investigated, modeled and evaluated several options, pinpointing two potential solutions: a 100 mm staged (transverse strip) concrete deck removal of the negative moment region, followed by the removal of the positive moment region to limit long-term deflections (Option A); and spot repairs combined with impressed current cathodic protection (Option B).
Designing for the Unknown
Since the bridge components were built decades ago, some conditions could only be assumed until construction. Understanding this uncertainty, ISL designed both options to provide flexibility once the bridge’s true condition was revealed. Option A was selected based on contractor availability and pricing.
Unique Hybrid Approach
To further protect from deterioration, the team planned to eliminate the joint by adopting a semi-integral abutment conversion. Standard practices coupled with the length of the bridge and thermal movement made this impossible. Taking an innovative approach, ISL moved the joint off of the bridge and incorporated a sliding surface under each approach slab, ultimately offering a unique hybrid approach to semi-integral abutments.
ISL kept sustainability in mind from predesign through construction. Designing to minimize waste, the team contacted suppliers to determine standard sizes to ensure elements were fit around these sizes wherever possible. For instance, to ensure no lengths of rebar went unused, ISL accommodated the standard 9 m reinforcing steel into the design by specifying 6 m lengths in some spots and 3 m lengths in others. The same concept was applied to form work and all other construction materials.
Meeting the Client’s Needs
Not only was the project completed on schedule and approximately $600,000 under budget, but ISL also aligned it with Saskatoon’s Core Bridge Strategy and Strategic Goals of Asset and Financial Sustainability, Quality of Life and Moving Around.