Which Railraod? Rail PIns are the screw-in type (European), not "Dogspikes", as in US practice.
China, Thailand, Malaya?
Rifles may give clue, old style T38s (No front sight ears.)..that would put it in China, probably.
4 wheeler is what is called a "Speeder", ( with a small petrol enging on back ,Hidden by legs of soldiers.) Park bench was the usual seating arrangement. May be a "Hand push" version....used by section gangs doing Line Maintenance.
I think some people would call it a handcar or maybe kalamazoo. You can see the see-saw hand pumps sticking out between the soldiers. Maybe they were a part of an Independent Garrison Unit in Manchuria. Neat pic.!