During the 2003 blackouts, many crossing the bridge reported a swaying motion. The higher-than-usual pedestrian load caused this swaying, which was amplified by the tendency of pedestrians to synchronize their footfalls with a sway. Several engineers expressed concern about how this would affect the bridge, although others noted that the bridge did withstand the event and that the redundancies in its design—the inclusion of the three support systems (suspension system, diagonal stay system, and stiffening truss)—make it "probably the best secured bridge against such movements going out of control". In designing the bridge, John Roebling had stated that the bridge would sag but not fall, even if one of these structural systems were to fail altogether.