In an extraordinary feat of construction, The Canopy was built in the Les Halles neighborhood of Paris, atop the second busiest shopping center in France and the largest underground railway station in the world, while both of them were still functioning! The challenges and the site’s historical importance add another layer of complexity. The skillful handling of these challenges with exceptional feats of engineering and brilliant architecture is a feather in the caps of Patrick Berger and Jacques Anziutti. This documentary expands on the thought processes and construction technology that went into building it. 

Youtube for Architects:Europe’s Biggest Construction Site | Mega Constructions | Free Documentary - Sheet1
The Canopy_©YouTube video Europe’s Biggest Construction Site | Mega Constructions | Free Documentary

Vision and History

The vision for The Canopy was to make a gateway to Paris through a monumental structure that would house a conservatory of music, a multimedia library, and spaces dedicated to urban culture other than the pre-existing shopping center and railway station. This 6-hectare site is a subterranean city beneath Europe’s largest pedestrian zone consisting of the shopping center and Châtelet-Les-Halles station. It reaches a height of 24 meters and stretches for 500 meters up to the Place du Châtelet.

Previously this space housed the famous Victor Baltard-designed glass and iron structure that gave Les Halles its name which was a hustling bustling area of merchant stalls that lasted a century. In 1971, the marketplace, unable to compete in the new market economy, was dismantled. Soon after, it came to be known as ‘the pit’ due to the construction of the new underground railway station. This project is the latest episode in the story of a neighborhood that has seen vast upheaval in the past two centuries. 

Les Halles Razing_©Wikipedia

Challenges

It is one of the most complex work sites of the 21st century. It had two main logistical problems. First, in its present state, the current building would be unable to support the colossal canopy, the framework of which was equivalent to the weight of the Eiffel tower. And second, keeping the shopping center and station open to the public throughout which means millions of people would be walking under the construction site separated only by a 14 cm slab. Due to this, they would have to be able to evacuate the station in under 10 minutes. Other than the building of this canopy, there were issues like the lack of direct street level access causing people to feel lost in the labyrinth of the station. The Châtelet-Les-Halles was built for 40,000 travelers a day but in the early 2000s, 7,50,000 people were occupying the station on a daily basis, which is nearly 20 times the number it was equipped to handle. Even the shopping center was non-existent at pavement level and had little to no access to open areas. Les Halles as a neighborhood, due to its incoherent chaotic space and petty crime, was not appreciated by the locals and tourists alike despite its rich historical value. 

The design they finally came up with dealt with making the space brighter, more comprehensive, and more accessible while also expanding it to accommodate the exceptional number of people who frequent it and finally, making the links between the underground and surface more direct and natural. 

Overcoming the challenges 

The documentary covers all the spectacular procedures for lifting the buildings, reinforcing the existing foundations, maintaining safety, and still completing a massive project in 7 years. To place a structure of this stature on the existing building would be destructive, simply because the columns would explode, unable to bear the weight. So, the columns and foundations would have to be reinforced first. The weakness and strength of each column were tested and using the technology available, simulations could be run to understand the load bearing capacity of the structure. 

To ensure the safety of people while construction, the more dangerous parts of it were done at night and restricted morning hours. During the in-situ construction of the framework of the canopy, the major constraint was keeping it uncovered as it acted as a light source and also a smoke evacuator in the event of a fire. To solve this, movable scaffolding was used and the work was done in sections. Along with this the documentary also addresses the construction of the roof garden over a shopping center and the expansion of the center and the station. Finally, the placement of glass tiles on the canopy is displayed. Due to the unusual shape of the canopy, each glass tile was different, and hence, new ones had to be ordered in case of damage on site. Fortunately, only 3 percent of the glass tiles got damaged, which is far less than on a normal construction site. 

After all these challenges and innovative solutions, this project finally came to completion in 2018. The station and shopping center were at last in proportion with the ever-increasing number of customers. For all the people involved in its design and construction, it is an extraordinary feat and a matter of pride to associate themselves with it. The documentary is well worth a watch with its exemplary graphics and video sequences that connect the viewer with the narrative and the structure. For all structural, and architectural enthusiasts and curious minds, this documentary is for you. 

References 

Free Documentary, n.d. Europe’s Biggest Construction Site | Mega Constructions | Free Documentary.

Available at: <https://www.youtube.com/watch?v=yyVttOMYGXQ&t=42s> [Accessed 1 June 2022].

Author

Rishima is a fifth year architecture student currently interning in Pune. She is an avid reader and occasionally blurts out coherent thoughts. She believes creating an equitable space for all and providing a uniform experience regardless of gender, sexual preferences, age, abilities, class and caste is the responsibility of each architect.

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