The Kanaka Creek is designated as a Major Route structure and forms part of the BCMoTI’s critical route in response to a disaster. There are five lanes of traffic, two northbound lanes to Maple Ridge and three southbound lanes to Albion.

Built in 1984, the Bridge consists of three simply-supported spans for a total bridge length of about 42 m. The superstructure consists of 600 mm deep BCMoTI prestressed twin cell box stringers and concrete deck overlay. Expansion joints are located over the piers. Each substructure unit consists of a conventional concrete pier cap with one row of 305 mm diameter vertical steel pipe piles. Steel pipe piles are filled with concrete to the riverbed and the rest of the piles are filled with sand. The bridge deck can engage in diaphragm action longitudinally from North to South Abutment. Dowels between the superstructure and substructures will need to resist the seismic inertial force demands.

Bridge is more than 35-years old. SNCL’s structural group recommended two good value retrofit solutions: i) additional dowels at abutments, and ii) installation of link slab above pier. Proposed solutions are much less expensive than other retrofitting options but significantly reduce the risk of collapse, providing a great increase in overall safety at a lower cost. As a result of our excellent technical expertise and innovation the client was able to find a solution that represented good value and the objectives it set out to achieve.

During the design process, the Project Manager and SNCL’s structural group worked closely with other inhouse discipline leads and the client to resolve issues such as geotechnical liquefaction, environmental impact on the creek and wildlife, traffic demand for highway users, construction staging and feasibility and more. Both the design and construction phases of the project were successfully executed on schedule and within budget, benefiting the local communities of Kanaka Creek and Maple Ridge

The structural team evaluated four different seismic performance options. Detailed comparison was done to recommend the one with the best value. Environmental sensitivity was a key issue for this structure as it is situated in a water creek. Project manager’s direct and frequent communication with each discipline leads and the client played a major role in the successful execution of the project. Throughout the design process, SNCL multi-disciplinary design team had internal weekly progress meetings to discuss design issues and solutions. This allow the team to identify issues and changes early so that they can be resolved or brought to the client’s attention promptly. This also allows inter-discipline coordination and review to happen throughout the design phase.The project manager also kept close and direct communication with the client, the proactive liaison helps each discipline to understand the needs and preferences of the client so that they can incorporate these details in the design. This reduced the cycles of review and comments between the design team and the client. The retrofit design involves drilling deep holes through the superstructures into the substructures. The technology to avoid existing rebars and other embedment during these deep drillings are critical to the success of the retrofit construction. The structural team consulted with several industry experts and came up with the plan of using combined drilling and coring of small diameter holes.

The project was completed by SNCL’s inhouse multi-discipline team (structural, traffic, geotechnical and environmental). Their combined experience contributed to the communication efficiency and overall success of the project. The seismic retrofit achieves the goal of improving seismic withstand capacity. The scheme chosen was designed to be simple, safe and easy to construct; to minimize the impact to the environment and the travelling public and provide the best value to the client.