"We have been working since Paris' bid for the Olympics," Debrincat told AFP. "At the time, we had a rather rustic modeling, with a big Excel spreadsheet" to see what services were possible, starting from a fictitious calendar based on the London events in 2012.

Things obviously became more concrete when Paris was officially chosen to host the Games in September 2017.

Laurence Debrincat's team -- fifteen full-time people -- was first interested in the capacities of stations and stations, which are, she says, "a rather limiting factor". Many metro stations, in particular, were not designed to accommodate crowds.

Typically, the Etoile Royale, which will host equestrian events at the bottom of the park of Versailles, is served by the new tram-train T13. But this one is very insufficient to transport the expected spectators.

"We must not send thousands of spectators on lines that do not have the capacity because it can be extremely dangerous, create crowd movements, etc." "So, we started looking for stations a little further. Either it's still within walking distance, or it's not, and in this case, we worked on shuttle buses."

For the Royal Star, you will have to take a bus to Versailles.

Running these shuttles requires a lot of work, since it is necessary to create ex nihilo real temporary bus stations that will "send the buses in bursts". This also requires finding space to park said buses.

Electric buses parked in their depot in Rivery, near Amiens, on May 27, 2019 © Jean LIOU / AFP / Archives

The seven million spectators of the Olympic Games, from July 26 to August 11, 2024, must be able to reach the 25 competition venues by public transport. In the middle of summer, when a third of regular travelers are on vacation.

- 'Olympic app' -

"During the day, we will have the equivalent of a big winter day, (with) trips that will be much more concentrated in Paris and at the sites" --12 in the capital and 13 in the suburbs--, predicts Laurence Debrincat.

"We compared the traffic line by line, hour by hour, with the usual service capacities in the summer to ask: +is there a need to strengthen the offer or is it like this?+" Transport operators will have to be ready.

"The closer you get to the event, the more detail you get," Debrincat said. There are the number of barriers needed to channel crowds, for example. The organisers regularly check in with representatives of the International Olympic Committee (IOC).

"We have now set up a much more complicated model that allows us to anticipate flows throughout the network" by taking into account the places of residence of spectators. "And we will wait for the statistics of single ticket sales, which will allow us to refine our hypotheses," she said.

A bus chartered to transport supporters arrives in Bordeaux, March 25, 2023 © ROMAIN PERROCHEAU / AFP/Archives

"We made observations (...) to find out how far in advance the spectators arrive and how long it takes them to leave. There are sites where spectators will really have to leave very, very quickly because there will be several sessions during the day."

All this gives "days that are more complicated than others", July 30 being according to her "the most complex day".

To guide spectators, IDFM is working on "an Olympic application", a variant of its usual app. "We will exchange in the coming weeks and months with other route planners", such as Google Maps or Citymapper, to propose routes passing through lines with enough capacity.

Now that the transport plan is established, IDFM is working on "Plan B". Plan alternative routes in case of breakdown, of course, or consider other difficulties: What happens if the tests are delayed? "There are also competitions that can be postponed the next day if the weather conditions are really terrible," says Debrincat.

© 2023 AFP