I’ve passed through the Gare du Nord in Paris twice, and I agree with the general assessment of the station: it serves its purpose of moving people in and out of the city, but it’s a mess in terms of the surrounding streets and it’s a somewhat grim experience.
In broad terms, the station was constructed as part of the second wave of major train stations, after train travel had advanced from its origins, but before traffic reached the heights of the twentieth century. There are few, if any, major stations of this era remaining in the US: we replaced them during the twentieth century with a later wave of modern buildings, including, here in New York, Grand Central Terminal (1913) and Penn Station (1910). The Gare du Nord, unsurprisingly, has been altered and expansed several times.
There are plans for another expansion to be completed before the 2024 Summer Olympics are held in Paris. But those plans do not substantially change the train-oriented areas of the station. Instead, they add a lot of new space to the back of the building and reconfigure the pedestrian access to the platforms. In short, people heading to the platforms from the street or the Metro will be walking past a bunch of new retail instead of walking straight to the trains. The uproar over the plans is based on that fact.
This conflict is not one of architectural design. Rather, it stems from economics, which is a part of architecture that is not talked about so much. Transportation terminals – train stations, airports, and bus stations – have as their function quickly and efficiently moving people to and from the transportation. That function is critical to the health of cities, but it does not in itself make money. Terminals are big buildings on expensive centrally-located real estate, but their function benefits the economy as a whole rather than those who own and operate the terminals. The answer to this has always been to put more and more retail and services in the terminal building, to make money from rent. Penn Station was demolished in the mid-1960s, but its beautiful central spaces had been partially taken over by new retail a decade earlier. Grand Central had some truly awful retail added in its concourse before the 1990s-2000s restoration; the restoration included created some better-looking retail on the formerly unused east balcony. The extreme end of this phenomenon in New York is the World Trade Center PATH station, where a large subway station has a huge mall above and around it.
The problem at the Gare du Nord isn’t the design of the proposed alteration. The problem is the assumption that every single piece of land has to be making money. That assumption isn’t limited to Paris, or the French rail company SNCF, or “the west” and it has the effect of warping architectural design and development.