Tramways are lightly laid railways, sometimes with the wagons or carriages moved without locomotives. Because individual tramway vehicles are not intended to carry the weight of typical standard-gauge railway equipment, the tramways over which they operate may be built from less substantial materials. Tramways can take many forms; sometimes just tracks temporarily placed on the ground to transport materials around a factory, mine or quarry. Many, if not most, use narrow-gauge railway technology. The trains can be manually pushed by hand, pulled by animals (especially horses and mules), cable hauled by a stationary engine, or use small, light locomotives. At the other extreme they could be complex and lengthy systems, such as the Lee Moor Tramway in the county of Devon, England, in the Unit