Class 4: 60 mph for freight, 80 mph for passenger. This is the dominant class for main-line track used in passenger and long-haul freight service. Examples are most of the suburban trackage of Chicago's Metra commuter railroad, including its own Rock Island District west of Blue Island and Milwaukee District West Line west of Bensenville (also a Soo Line freight route); plus BNSF west of Cicero Yard and Union Pacific (former C&NW) west of Proviso Yard; New England Central's entire main line between New London, Conn., and East Alburgh, Vt.; and the Arizona & California (ex-Santa Fe) between Matthie, Ariz., and Cadiz, Calif. Source