Between the top of Hanwell locks and the foot of Norwood locks is Three Bridges. Here a road goes over the canal at the same point as a railway goes under it. That's only two bridges, actually, but who's counting? And "Two Bridges and a Buttress", while a more accurate description, is hardly a memorable name.
Ths picture shows the view from the railway line. The canal is in the iron trough visible through the near arch.