public boolean ajouterStation(Station st) {
        if (st instanceof ArretDeBus && this.getNbArretDeBus() <= NOMBRE_MAX_ARRETDEBUS) {
            return this.stations.add((ArretDeBus) st);
        } else if (st instanceof StationTaxis && this.getNbStationTaxi() <= NOMBRE_MAX_STATIONTAXI) {
            return this.stations.add((StationTaxis) st);
        }
        return false;

    }