Paris RER B blocked - Châtelet les Halles

In Châtelet les Halles station at Paris in France, this RER B will remain blocked at the platform for several minutes. We can see on the opposite platform that everything is fine on the RER A, no problem to report. This parking of the RER B is due to the fact that the line makes an exceptional terminus at Gare du Nord because of maintenance. The video was taken on the platform towards Roissy CDG/Mitry Claye Airport (north of the line), and Châtelet les Halles is the last station before this terminus. Instead of parking the train under the tunnel until the platform of Gare du Nord is free, this RER stays at Châtelet until the train in front has freed the platform of Gare du Nord.