Category: Transportation

Schreyer Award and Award of Excellence Winners: Harbourside Engineering Consultants and gbi

The original Champlain Bridge joining Montreal and Brossard, Que., was one of Canada’s busiest vehicular crossings until its closure in 2019. Nouvel Horizon Saint-Laurent (NHSL), the contractor designated to deconstruct the structure, in turn engaged Harbourside Engineering Consultants to serve as the project’s deconstruction engineer.

Under this arrangement, Harbourside and subconsultant gbi were responsible for all phasing, sequencing, temporary works, means and methods for the bridge’s deconstruction, which required meticulous planning and adherence to environmental, site and community constraints.

The project team’s ideas and methods for the deconstruction process helped minimize environmental impacts and ensure this historic and high-profile project’s success.

The decision to replace

Operating from 1962 to 2019, the original Champlain Bridge was a 3.4-km long, six-lane structure. Situated over the Saint Lawrence Seaway, it faced ongoing structural deterioration, which eventually rendered its maintenance economically unfeasible.

Consequently, Jacques Cartier and Champlain Bridges Incorporated (JCCBI), a federal Crown corporation, opted to replace the aging structure with the new, cable-stayed Samuel De Champlain Bridge. The corporation selected NHSL, a partnership between construction company Pomerleau and demolition contractor Delsan AIM, for this undertaking.

The project was divided into three zones:

• Section 5, including the concrete approach spans west of the steel structure to the abutment on Nun’s Island.
• Section 6, comprising the steel superstructure (i.e. trusses) located near and above the Saint Lawrence Seaway.
• Section 7, including the concrete approach spans east of the steel structure to the abutment on the Brossard side of the river.

Tools for the job

The process required both innovative thinking and detailed knowledge of existing deconstruction methods and structural engineering theory, so as to ensure an efficient process and uphold the project’s objectives.

The project team incorporated sophisticated jacks in the lifting and lowering of concrete spans, as well as real-time monitoring of load distribution and barge deflection, movement and rotations, using a variety of sensors that allowed for a high level of control throughout critical operations.

The suspended span deconstruction—being located over the economically vital Saint Lawrence Seaway, where disruptions were not permissible—required exceptionally careful planning. The work was completed in January, under the most difficult environmental conditions during the seaway’s yearly closure. The span was lowered as a single segment with six strand jacks to a pair of barges.

Detailed jacking and piece-by-piece dismantling procedures for the truss cantilever and anchor arm spans facilitated the safe and efficient deconstruction of the steel superstructure. Harbourside’s contributions enabled this process to be completed safely and effectively.

The well-controlled and meticulous nature by which the deconstruction was completed also helped to advance the image of the engineering profession in the eyes of the public. Further, the successful execution of the methods developed during this project will allow for similar methods to be considered for future projects.

Challenges countered

This was a unique, high-risk engineering project with many challenges, in part due to the structure’s degraded condition. The means, methods and temporary works design had to ensure the safety of workers and the public, protect the environment and mitigate site constraints.

One of the main challenges was practically and economically removing elements of the bridge without compromising the structural integrity of the remaining structure. The suspended span lowering process and the anchor arm’s deconstruction, by way of example, called for the ability to control the load between trusses, to prevent elements in the system from becoming overloaded and to ensure the remaining truss members remained stable.

Other specific challenges included:

• protecting the new, adjacent Samuel de Champlain Bridge, which opened in 2019.
• the inability to disrupt Saint Lawrence Seaway vessel traffic, which meant contingency plans were required to mitigate risks (such as mechanical equipment failure) and major operations had to be timed to occur during the seaway’s winter closure.
• allowing within the deconstruction sequencing for the safe and complete removal of specific elements of the bridge designated for R&D or reuse.
• accounting for and accommodating differential deflections and rotations for the removal of spans via barge.
• the restriction of equipment mobility by the relatively narrow jetties that could be built out into the river to access Section 6’s steel spans.

Taking all of these challenges into consideration, Harbourside’s methods significantly reduced costs and scheduling, reduced impacts on the public and the surrounding environment and minimized risk for the contractors tasked with deconstructing the bridge.

Visible benefits

This deconstruction project not only provided a rare opportunity for residents and passersby to witness an engineering mega-project in action, but also brought substantial social and economic benefits to the region. With an estimated value of $400 million, the project generated employment opportunities for local contractors, suppliers and tradespeople, including equipment operators and ironworkers.

Moreover, the involvement of Harbourside’s engineers and drafters from Prince Edward Island and Nova Scotia underscored the project’s broader regional impact, demonstrating the collaborative nature of large-scale engineering endeavours and the opportunities they can create across provincial boundaries.

The project’s emphasis on research and development (R&D) has contributed to advancing knowledge of structural behaviour and deterioration. By leveraging insights gained from the deconstruction process, engineers and researchers can continue to refine methodologies and practices, ultimately enhancing the resilience and longevity of other infrastructure.

Also, recognizing the rich history and significance of the original Champlain Bridge to the local community, one of the concrete piers that supported its main steel spans was preserved and will remain on display to commemorate the historic structure.

Mitigating environmental impact

The deconstruction of the Champlain Bridge also prioritized environmental sustainability through various measures aimed at minimizing its ecological footprint and mitigating potential impacts.

One of the project’s key targets was to recover at least 90% of all deconstructed materials for recycling, demonstrating a commitment to waste reduction and resource conservation. This repurposing minimized landfill-bound materials, promoting environmental stewardship and the ‘circular economy.’

As mentioned, some of the specific bridge elements were designated for research and reuse. The deconstruction sequence ensured the safe removal of these elements, facilitating the extraction of valuable materials for future projects and contributing to ongoing efforts in sustainable infrastructure practices.

Proactive measures were implemented to address air and water quality concerns. A dust management system with water misters on the main barge helped minimize ambient dust during demolition. Captured water was treated before release.

Through collaboration with contractors and jacking specialists, efficient optimization of procedures cut the turnaround time for positioning, lifting, repositioning, lowering and deconstructing individual spans from an anticipated three or four weeks per span to about one week, minimizing disruptive activities and their associated environmental impacts.

Multifaceted goals

JCCBI’s goals for the deconstruction of the Champlain Bridge were multifaceted, encompassing cost-effectiveness, schedule adherence, public safety, minimization of disruption to the surrounding community and environmental sustainability. Working collaboratively with NHSL, Harbourside and gbi successfully met these objectives through a combination of innovative methods, meticulous planning and effective collaboration with stakeholders.

These methods significantly reduced costs and streamlined the deconstruction process, optimizing efficiency without compromising safety or quality. By minimizing downtime and accelerating the timeline for each phase of the deconstruction, the project was completed within budget and schedule.

Proactive measures were implemented to minimize risks and impacts on the navigational channel and infrastructure. Through meticulous planning and real-time monitoring of operations, hazards were effectively managed and disruptions were kept to a minimum, enhancing safety and community satisfaction.

As mentioned, careful deconstruction techniques ensured many materials were repurposed for future projects, thus contributing to the circular economy and environmental stewardship.

Through collaborative efforts and strategic planning, the deconstruction of the Champlain Bridge was executed efficiently, responsibly and with care for both the client’s priorities and the surrounding environment and community. In meeting JCCBI’s project goals, Harbourside, gbi and NHSL demonstrated a commitment to excellence and innovation in engineering.

Champlain Bridge Deconstruction, Montreal

Award-winning firms (deconstruction engineers): Harbourside Engineering Consultants, Dartmouth, N.S., and gbi, Montreal (Greg MacDonald, P.Eng., ing.; Wade Pottie, P.Eng., ing., PE; Calvin MacAulay, P.Eng.; Marc Tarling, P.Eng., ing.; Sarah Foster, M.Sc., P.Eng.; Todd Menzies, M.A.Sc., P.Eng.; David Mousseau, ing.).

Owner: Jacques Cartier and Champlain Bridges Incorporated (JCCBI).

Other key players: Nouvel Horizon Saint-Laurent (contractor).