The Big Bob Channel bridge and two neighbouring Little Bob Channel bridges span the Trent-Severn Waterway, a 386-kilometer canal of lakes and rivers that connects Lake Ontario and Lake Huron. Part of City of Kawartha Lakes Road 36, the three bridges lie within Bobcaygeon—the Hub of the Kawarthas—along one of the main links between southern and northern Ontario. After many decades of use, the deck tops, asphalt wearing surfaces, railings, parapet walls, sidewalks, and drainage systems of the 174-meter, steel-girder Big Bob Channel bridge and the two boat-girder, rigid-frame Little Bob Channel bridges had severely deteriorated, so CFA completed the preliminary and detailed designs for the rehabilitation of the three structures. A key element of both projects was that traffic on the heavily travelled tourist route be maintained throughout construction, which occurred in summer, at the height of the tourist season.
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- Rehabilitation of Little Bob Channel North and South Bridges on Kawartha Lakes Road 36 in the Village of Bobcaygeon
- Twin concrete “Boat” girder rigid frame bridges spanning the Little Bob Channel
- Replacement of concrete handrails and sidewalks, concrete repairs to decks
- Required support of suspended sanitary sewer and forcemain during construction
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Tim’s Writeups
Chisholm, Fleming and Associates (CFA) was retained by the City of Kawartha Lakes to provide detailed design and contract administration services for the rehabilitation of the Little Bob Channel North and South Bridges on East Street South (Regional Road 36) in the heart of Bobcaygeon.
The twin bridges, originally constructed in 1960, are 23.9 m single-span reinforced concrete rigid-frame bridges featuring a concrete deck and an asphalt wearing surface. Each deck is supported by concrete abutments set normal to the road alignment. A key project complexity was the presence of active water and sanitary mains suspended from the east side of both structures, requiring continuous protection and careful coordination throughout the project.
Our Challenges
- Aging structures with significant deck and concrete deterioration
- Coordination with active water and sewer utilities attached to the bridges
- Limited working space between twin structures and adjacent sidewalks
- Upgrading to meet current barrier and guide-rail standards
Our Approach
CFA conducted a detailed condition assessment and developed several rehabilitation alternatives, evaluating constructability, long-term durability, and community impact.
The chosen design provided a sustainable and cost-effective solution, ensuring minimal disruption to local traffic and uninterrupted utility service during construction.
Scope of Work
- Sidewalk Renewal: Removed and replaced concrete sidewalks on both bridge decks.
- Utility Protection: Temporarily supported water and sewer mains, removed and reinstated their protection systems.
- Barrier Replacement: Installed new box-beam barrier systems meeting modern safety standards.
- At-Grade Improvements: Built a new west-side sidewalk between the bridges and replaced the east-side sidewalk.
- Deck Rehabilitation: Removed asphalt wearing surface, repaired concrete, waterproofed, and repaved decks and approaches.
- Concrete Restoration: Repaired deck fasciae and wingwalls.
- Guide-Rail Upgrades: Installed new steel beam guide rails with compliant end treatments at all four quadrants.
Project Outcome
CFA’s integrated design and construction management approach delivered a safe, modern, and long-lasting solution while preserving the character of Bobcaygeon’s historic core.
The rehabilitated bridges now serve residents, travelers, and infrastructure systems with renewed reliability and extended service life.