Bridges connect communities to other communities, and for some areas, a bridge might be the only connection to the outside world.
Located in Bayfield, Ontario, in Huron County, the old Bayfield River Bridge was constructed in 1949 and was a 60.9 m long two-span modified warren deck-truss. As with most bridges built last century, it had undergone several rehabilitation and strengthening repairs, and exhibited advancing deterioration. It also had insufficient hydraulic clearance. In short, it was showing its age. For the growing community, the bridge was functionally obsolete and needed to be replaced.
The Ministry of Transportation (MTO) retained Egis to help with this project. We acted as Total Project Management to provide detailed design services and to assess the environment around the bridge, known as a Class Environmental Assessment (Class EA) Group ‘C’. Egis assessed the bridge and oversaw the design and construction of the new bridge.
Challenges Faced and Overcome
Constraints are inevitable in any construction project. With our decades of experience, we’ve learned it’s necessary to always be prepared and to work within any limitations and not against them.
With a project of this size and with a bridge this old, there was bound to be some project challenges. The first set were related to the environment – there were Species-At-Risk present near the bridge. Species-At-Risk (SAR) need to be dealt with carefully as any change could upset the ecosystem. At Highway 21 Bayfield Bridge there with Mapeleaf Mussels, with other (SAR) mussels possible. This posed a challenge as mussel restrictions are in effect all year and can only be re-located once the water temperature is above 16 degrees Celsius. There was other wildlife in the area, including Northern Brook Lamprey, Barn Swallows, Bats, and Turtles – all of which had to be accounted for. Another challenge was that in-water work was only permitted from August 16 to September 14, which impacted the project schedule.
The other major challenge was site access. During the construction phase, the site had a limited construction area and unreliable barge access, adding another layer of difficulty. The bridge was adjacent to a marina, which meant boat traffic. With the new bridge planned to be constructed in the same location as the existing bridge, both vehicular and pedestrian traffic had to be maintained during construction to ensure traffic flow of the community was not adversely impacted. To help with this, a 118 m long Temporary Modular Bridge with a 76.2 m span across the river was placed next to the existing bridge, and the road was temporarily shifted.
Integrated Project Solution
The main objective of this project was to replace the aging bridge, but there were additional objectives. These included minimizing grade and alignment offset, reducing overall structure length while providing a clear span across the river, and maintaining open views through the structure in a natural and recreational setting. This project also involved high-risk in-water work, and heavy lift parallel offline construction, both of which present a unique set of challenges
The Devil Is in The Design Details
Every bridge design has the most Crucial Stage. Using the right tools to test different designs can help reveal the best, most cost-effective choice, and lead to saving time and materials.
The Transportation Structures team at Egis worked on the following Design Details:
- Substructure and Thrust Block
- Caisson frame socketed 4m into bedrock
- Permanent composite steel liners
- Post-tensioned high-strength thread bars
- ‘Blind’ connection with bar couplers in grouted sleeves
- Alignment corbels for precision fit-up
The bridge is notable for it’s Arch Ribs, which has a conventional prismatic trapezoidal shape and hidden access hatch at the crown. The bridge has a Deck Steel Grillage and Hanger Arrangement, with hangers at 4m C/C spacing and vertical hangers with fork-and-pin connection and adjustable turnbuckle anchorage.
It Takes a Village to Build a Bridge
Every construction project is a team effort, and for this bridge, the construction was reviewed with the help of a General Contractor, a Specialist Erection Engineer, Heavy Lift Contractors, and others. Egis coordinated between all the project stakeholders to ensure the client’s and communities needs were met.
Full trial assembly was required and was completed a single rib lift during the process. To overcome the challenges posed by the water, the design was based on stick-building to avoid the need for any in-water works.
Building A Bridge That Endures
Replacing a bridge this old means we need to design and build one that will last even longer. Here are some highlights of the bridge’s durability:
- The bridge is made of Steel Deck Grillage – Metallized coating with premium topcoat.
- The Arch – ACR Steel with Metallized exterior surface with a premium topcoat
- The Hanger Type has a Parallel Strand System (PSS)
- Have Galvanized strands, waxed, and individually sheathed
- High-density polyethylene (HDPE) pipe external barrier
- The galvanized coating on exposed forks, pins, and accessories.
- Semi-integral abutments
- Full fixity connection between arch and thrust block
- Galvanized Post-Tension (PT) Bars
- Free-standing arches with no overhead bracing
- TL-5 barrier system with offset to arch ribs/hangers
Turning Possibilities Into Reality for our Clients and our Communities
The new Bayfield River Bridge design meets modern structural, functional, and performance requirements. The new bridge has a superior aesthetic design, and it provides pedestrian, cyclist, and vehicular access across the river, with a cantilevered sidewalk overlooking the town marina. The new bridge will help the people of the community for decades to come.