Lieux publics Bonaventure

For over 50 years, the elevated Bonaventure Expressway served as the main gateway to downtown Montreal. Originally built for the 1967 World’s Fair, the expressway was a significant urban landmark, but its development created a physical barrier between the adjacent neighbourhoods and reinforced car-centric infrastructure in the city centre. Rather than investing to extend its life, in 2015 the City of Montreal decided to demolish the expressway in favour of a new green promenade that stretches nearly six city blocks. 

Les Lieux publics Bonaventure was part of the larger Bonaventure urban infrastructure initiative led by the City of Montreal, to replace the downtown aging infrastructure with accessible green public spaces. While the project passed through multiple design teams over 13 years prior to the expressway’s demolition, its final vision was guided by Rousseau Lefebvre, coinciding with Montreal’s 375th anniversary at the time. The demolition of the Bonaventure Expressway marked a shift toward a more human-scaled, climate-resilient, and socially connected urban environment for downtown Montreal.

The removal of the Bonaventure Expressway opened over three hectares for continuous public space to improve access to nature and foster social connections. In addition to enhancing urban livability and community well-being, it presented a significant opportunity to reduce the reliance on cars in downtown Montreal, reconnect the fragmented neighbourhoods, and create a vibrant entrance to the city centre.  

Stormwater management was a key focus of the project, aiming to more efficiently manage and filter urban runoff on-site, increase permeability, create cooler microclimates to mitigate urban heat, and increase accessibility to nature within a densely developed environment – particularly in a neighbourhood that previously lacked park space. By replacing the large-scale grey infrastructure with green infrastructure, including rain gardens and vegetated islands, the project is able to significantly enhance environmental sustainability and ecological functions (e.g., pollination and carbon sequestration), and support urban wildlife and biodiversity. This nature-positive design thinking and prioritization of nature-based solutions paved the way for SITES certification, a program for sustainable land design and development administered by the Green Business Certification Inc. (GBCI). Rousseau Lefebvre pursued SITES certification from its inception, reflecting the deep commitment to sustainability and environmental regeneration. 

Finally, the site’s rich historic context was pivotal in shaping les Lieux publics Bonaventure, presenting an opportunity to create a poetic and engaging open space by blending urban biodiversity recovery with sculptural elements and public art, all the while advancing urban sustainability development goals.

While detailed climate data was not readily available during the development of this project, design decisions were intentionally made to enhance climate resilience, sustainability and biodiversity recovery. Particular attention during the design phase was paid to vegetation, with the selected plants chosen based on their ability to adapt under varying stormwater conditions and urban environmental stressors. 

In addition to vegetation adaptability, stormwater management was also a key consideration: the site was designed specifically with larger storage volumes in mind to hold stormwater on-site and infiltrate it efficiently within three days. The design maintains a balance between pervious and impervious surfaces (roughly 50-50) and integrates physical topographic modifications, such as depressions and mounding, as well as below-grade storage improvement presenting practical strategies for both water retention during heavy rain and resilience during drought. 

Technical input was provided by engineering collaborators who analyzed IDF curves and 85th percentile rainfall events, which directly informed the implemented solutions. While future precipitation projections were not formally included, the design integrates flexibility to handle rainfall uncertainty by incorporating additional capacity exceeding current standards to accommodate uncertain future rainfall volumes. By translating technical input into functional design elements, les Lieux publics Bonaventure Project merges ecological, technical, and aesthetic goals, favoring practical, adaptable solutions rather than prescriptive calculations. In addition to the engineering data, key guidance was provided by the city’s stormwater management regulations, in addition to the SITES certification performance measures, to ensure that water retention, infiltration, and pollutant control were embedded in the design. 

During the planning phase, Rousseau Lefebvre and the collaborators focused on identifying actions that would meet both environmental and community priorities. The plan for the new green promenade aimed to enhance multi-modal access, and centred around the integration of green infrastructure and recreational facilities – more specifically the use of native vegetation and nature-based systems to enhance urban livability. Livability as the guiding principle is further reflected in the inclusion of adaptable benches, flexible urban furniture, and functionality in regards to both the green infrastructure system for stormwater management, and in creating an adaptive space for public gathering. Extensive public consultation was central to the planning process, where community feedback directly informed decisions concerning amenities and design. 

As the primary entrance to downtown, the site’s context demanded a design that conveyed both ecological performance and civic identity. Establishing conditions for fast-growing vegetation was prioritized to signal maturity and ecological resilience early in the project’s development. The integration of public art was critical to reinforcing cultural identity and a sense of community. Two monumental installations, Source by artist Jaume Plensa and supported by France Chrétien Desmarais and André Desmarais, and Dendrites designed by Michel De Broin, mark the northern and southern gateways of the boulevard. The collaboration between the City of Montreal and private donors was the first partnership of its kind to integrate international public art into a major urban development project. 

Pursuing SITES certification helped to identify actions by emphasizing sustainability from design through construction and maintenance. For instance, meeting the SITES requirement to keep stormwater on-site meant water had to infiltrate rather than just being detained - a key action that reinforced long-term sustainability goals and ecological performance measures. The planning process brought together a diverse group of collaborators, and the SITES certification process put forward the advantages of the landscape, requiring more time spent on the planning and design phase early on in project development in order to meet the requirements. Pursuing SITES certification not only provided a framework for best practices to deliver on sustainability goals, but also offered a way for the City of Montreal to showcase leadership in sustainable urban design. 

Summary of design intentions: 

• Create a prestigious, functional and friendly city centre entrance;
• Utilize green infrastructure to manage stormwater on-site, reduce urban heat, and support long-term ecological performance;
• Reweave the adjacent neighbourhoods, both in the north-south and the east-west axis; and
• Support urban redevelopment while reconnecting people with nature through immersive public spaces.

Construction of les Lieux publics Bonaventure began with the demolition of the original 1967-built expressway structure in 2015, making way for the construction of a six-meter-wide landscaped sidewalk and a 1.6km-long bike path. Beyond the transportation infrastructure improvements, Rousseau Lefebvre reimagined the linear corridor as a series of interconnected public spaces. A 396-meter linear bench acts as a defining element of the project’s design, anchoring the boulevard and framing the public recreational amenities which include lounge chairs, picnic tables, and play areas, as well as outdoor exercise areas, and dog-play spaces. 

Sustainability was embedded into every aspect of the project’s construction. A central focus during implementation was supporting the rapid establishment of vegetation, particularly trees, to create an immediate sense of maturity and support ecological performance. More than 300 trees and 30,000 shrubs and perennials were planted, with 53 percent native species. Stormwater management was another defining element of implementation with over 80 percent of visible stormwater features integrated as accessible public amenities. 

Finally, the public art installations of Source and Dendrites played a major role in shaping identity and experience. Source is a 10-meter-tall public artwork at the southern entrance, symbolizing Montreal’s diversity, vitality, and creative spirit, and Dendrites is a pair of staircase sculptures at the northern entrance which resemble industrial trees made of weathering steel, symbolizing the site’s manufacturing heritage and the branching, interconnectedness of urban life.

Les Lieux publics Bonaventure officially opened to the public with a ceremony in 2017. This project underscores the value of close collaboration, particularly with contractors, whose involvement and input were essential to project implementation. Rousseau Lefebvre were the first professionals in North America, and les Lieux publics Bonaventure remains the only project in Canada, to achieve SITES certification. Although meeting SITES criteria required additional time and consideration during the planning phase to address questions around materials, maintenance, and long-term performance, etc., it streamlined construction documentation and improved implementation efficiency.

The completed project transformed the formerly industrial corridor into a sustainable urban landscape that reconnects the fragmented community. The new boulevard connects key multi-modal transportation routes, introduces extensive green infrastructure and a variety of new recreational opportunities, and has quickly become a beloved public amenity. The interdisciplinary collaborators were instrumental to the project’s success by aligning technical, ecological, and aesthetic goals effectively. Immediately after opening, community members responded positively, especially children of the neighboring preschools, recognizing the sense of enclosure and refuge the new boulevard now provides from the surrounding downtown environment. The community’s adoration underscores the importance of human-centred design in urban space, and an exemplary project in balancing ecological and technical performance to advance sustainability and enhance both community well-being and climate resilience. 

Guided by the SITES certification process, les Lieux publics Bonaventure demonstrates measurable resilience through the thriving vegetation, effective stormwater management system, and active public use. The project received silver level certification in the spring of 2018. Vegetation and tree growth are monitored as key indicators of ecological health, and stormwater infiltration and retention performance continue to be observed regularly to ensure functionality. Rather than relying solely on predictive models, the design team adopted an observational and adaptive monitoring and management approach, allowing on-the-ground performance to inform ongoing maintenance. 

The boulevard’s extensive greening is projected to increase canopy cover to 27 percent within the next 10 years and will help sequester 4 metric tons of CO2 in the first year alone and over 310 tons across 30 years. The addition of grassed areas, rain gardens, and planting beds serve the adjacent impervious surfaces by capturing and treating runoff, significantly reducing the volume of water that would have otherwise been directed to the municipal stormwater system, and improving groundwater quality.

Throughout the project, the landscape architect (Rousseau Lefebvre) played a pivotal role in delivering both the technical and ecological performance targets and the emotional experiences, acting as the central mediator between the interdisciplinary design team - including engineers and ecologists - and the public. In this way, the landscape architect was responsible for ensuring that every aspect of les Lieux publics Bonaventure was not just functional and resilient, but also aesthetically meaningful and responsive to the needs of the community. By leading with a design approach that emphasizes poetic and human-centred principles in the landscape, while also incorporating technical rigor, the landscape architect was critical in translating complex engineering and ecological ideas cohesively into a public space capable of adapting to changing climate conditions and community needs.

Moving forward, the emphasis of the project remains on adaptive maintenance. For example, the continued monitoring of trees and vegetation will be used to assess growth and ecological health and performance. Likewise, ongoing observation of the vegetation will assure that the green infrastructure continues to infiltrate and retain stormwater effectively and perform as intended, with adjustments as needed to respond to changing conditions. Ultimately, les Lieux publics Bonaventure stands as exemplar for how urban development can advance sustainability initiatives, showcasing the potential for the integration of rich urban history, ecological resilience, and community development to foster livability within the evolving downtown city context.

• The Sustainable SITES Initiative - Les Lieux publics Bonaventure
• Rousseau Lefebvre - Les Lieux publics Bonaventure: From Highway to Urban Plaza a Case Study for Sustainable Design
• Rousseau Lefebvre - Les Lieux publics Bonaventure Project
• Ville de Montreal - Les Lieux publics Bonaventure Concept D’aménagement (FN - Planning Concept Document)