Paris (AFP)

Many applications help Ile-de-France residents to find their correspondence every day. But in times of strike, the challenge is considerable to take into account the idle bus lines and closed metro stations.

How do route planning applications work?

Whether official or commercial, all route planning applications draw their information on public transport timetables from the same source. In the Paris region, Ile-de-France Mobilités provides so-called "open-data" (that is, reusable and royalty-free) for RERs, metros, trams and buses carriers.

Application publishers must therefore stand out by relying mainly on their algorithms which, from this data, try to generate the quickest and most suitable route based on a certain number of parameters.

Some applications also add other layers of information: satellite images or images captured by mapping vehicles, traffic and traffic data from smartphones or on-board GPS that share their location.

How do they adapt to the strike?

The applications tested this week by AFP display all the warnings provided by the regional operator. However, they do not necessarily take them into account in the itineraries offered.

Google Maps, for example, displays "imminent" metro arrivals and "every three minutes" services for non-stop lines. The Mappy site also offers routes passing by unserved lines, while displaying a warning.

"We are not always able to get around the closed lines, that's why we complete it with info on disturbances," said AFP director general Mappy Florence Dereel. "The idea is also to be transparent" on the choices made by the algorithm, she adds.

The Citymapper application, which specializes in large cities, has obviously made more efforts: a "disruption bulletin" appears at the reception and details with humor the situation on each line. The route search "dodges" besides those who are stationary. However, clicking on a closed metro station always shows the usual service hours.

"The RATP publishes the frequency estimates at the end of the day. We are trying to take the theoretical data and adapt it so that it better reflects the reality," the company, which said it uses a "mix" of automated and manual data.

What is at stake with real-time data?

The lack of relevance of certain answers is sometimes due to the delay in updating the data, because Ile-de-France Mobilités does not provide homogeneous real-time information on the territory concerning the positions of trains, metros, trams and buses. which could take into account all the hazards.

"We are working on it, but we are not there yet," confirmed an official interviewed by AFP, concerning this information long awaited by the players in the sector. For the coolest news, the regional transport authority also recommends using its official ViaNavigo application.

But even when real-time data becomes available, strikes will remain a difficult hazard to anticipate. "If you manage to have the exact time of the passage of your train, you will not be able to know if it is crowded and if you will have to let several pass before you can get on", explains Florence Dereel.

And when almost all the lines are stopped, no algorithm can work miracles. To always display routes, Google Maps, Apple Maps, Mappy, Citymapper, Uber or Moovit therefore all swear by alternative modes of transport (hybrid bikes, shared bikes, scooters, etc ...).

© 2019 AFP