The 3ft (914mm) gauge Durango & Silverton Narrow Gauge Railroad (D&SNG) in Colorado, one of the USA’s most famous steam operated narrow gauge railways, has begun using diesel locos more regularly instead of the fleet of ex-Denver & Rio Grande Western Railroad steam locos which previously worked almost all trains.
The increased frequency of forest fires, some of which have been blamed on coal-fired steam locos, is one reason for the change, although another is the relative ease and economy in using diesel locos.