In America, Amtrak's Viewliner sleeper cars are 10'6" wide (official width as per their virtual tour), matching the Amfleet coaches and cafes in the fleet (Budd specifications for the cars, and visual observation). The Heritage and Horizon fleet are culled from all the railroads they absorbed when they were created, and range from 9'6" to 10'6". Their Superliner fleet is 10'2" wide (official width as per their virtual tour for the sleeper, visual observation for the others).
Commuter railroads will generally run the 9'6"-10'6" gamut as well (visual observation across MBTA, MTA, CT DOT, NJT, SEPTA, and MARC rolling stock).
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