A fuel supply system for mounting to an undercarriage of a locomotive includes a first enclosure and a second enclosure that are disposed below the undercarriage of the locomotive. The first enclosure is configured to extend partway along a length of the undercarriage and is designated to store a first type of fuel therein. The second enclosure is located adjacent to the first enclosure and configured to extend parallelly with respect to the undercarriage. The second enclosure is designated for enclosing components that are configured for supplying a second type of fuel to an engine of the locomotive.