How do crowds move and a rumor spread? Meeting with a “foulogist”. A camera films the movement of passengers, volunteers equipped with red or blue vests.
“The unspoken rule in transportation is to let go down before you go up. Here we test the impact of the disruptors, by designating, each time, one or more passengers who must be undisciplined,” indicates Mehdi Moussaïd, who times each entry and exit of the RER with his smartphone.