ZÃ 1\/4 rich S-Bahn ( German S-Bahn ZÃ 1\/4 rich is a suburban rail system that links the City of ZÃ 1\/4 rich to its agglomeration . Unusually among rapid transit services , the ZÃ 1\/4 rich S-Bahn provides first class commuter travel ; about one-fifth of seats on each train are first class .