Industrial 'Internal User' stock
Outside the cramped towns there were mills and dairies and of course larger industries such as brick works, steel works, glass works, mines of various sorts and quarries. Larger industries such as collieries and steel works often had their own internal rail networks with their own `internal use only' stock and locomotives. The stock would often be very dilapidated as it had no advertising function, but private locos were usually well maintained and tidy. The internal user stock would not have been travelled off the property of the owning firms and wagons were usually clearly marked as being for internal use only. It was common practice with internal use railway wagons of a fairly standard type to paint the top few planks or the metal corner plates in a bright colour to make internal stock easier to identify
A trawl through books on industrial locomotives will often turn up some more unusual wagon types, many of which make attractive models and help to identify the nature of the industry. Steel works had plate wagons and they also often had their own coke plant requiring coke wagons, usually hopper types. Coal mines used large numbers of standard mineral wagons, often retaining old designs long after these had disappeared from the railway proper. Vehicles relating to specific industries are illustrated in the section on Lineside Industries.
The larger private lines sometimes carried 'workers trains', generally made up of old, usually four wheeled, coaches. The Grafar 4 wheeled coaches would be ideal for this, failing which you can make up simple coaches using the Peco fifteen foot wheelbase brake van chassis. Many of the older four wheel coaches had straight sides with no 'tumblehome' so one option is to use the body from a Peco pallet van or fish with new sides mounted on a Peco brake van chassis. Cut the new sides from clear plastic card and trim to fit, place small rectangles of sticky labels where the windows will be and scribe in door frames, adding handles from scraps of 10x10 thou rod. Paint over the top and when dry (about a day later) remove the sticky labels. By the 1940s old coaches were becoming rare and hard to find so some firms and mine owners bought old railway goods vans and fitted these with seats for the workers. Most of these converted vans had no windows but the doors were often removed and replaced with a simple canvas curtain. The original company livery was usually painted over to make sure these old vans did not find their way back onto the railway system proper but this would have been a simple, dull, paint job. Most seem to have had no markings other than (occasionally) a number.
Industrial Locomotives & Associated Works
Most industrial track was laid on fairly light road-bed, often with very tight curves and so would not have been accessible to heavier classes of railway locomotives. Generally on industrial lines 0-4-0T and 0-6-0T locomotives were the norm and privately owned locomotives often had unusually short wheelbases to enable them to negotiate tight curves. In many locations where 0-6-0 locomotives were used there was no flange on the middle wheels to allow them to negotiate very tight curves without de-railing.
The Peco small tank loco kits (although a little over scale) and the Gem 2F saddle tank kit are suitable for periods set after about 1850. The Graham Farish 0-6-0 side tank engine would serve for a larger industrial layout set after about 1920 and the Graham Farish 'Austerity' 0-6-0P would serve well for post-war layouts. Petrol and diesel locomotives appeared on private lines before the railway companies took much interest and the latter are now a regular feature of privately owned lines. Unfortunately most of these locomotives were very small but something might be produced based on the Graham Farish 'motor bogie' originally produced for their Diesel Multiple Unit. There is a kit of a 'Sentinel' industrial steam locomotive to fit this motor unit on the market and although compromised by the design of the bogie it looks well enough. Personally I like the small 0-6-0 diesel-electric shunter from the Japanese firm Kato, Japanese N is scaled at 1:150 and this results in a sufficiently short wheelbase to suit many older industrial locos. As bought this little loco resembles several seen in photographs of post 1950s coal mines and steel works.
At larger works the locomotives would be maintained on-site, requiring workshops and probably a hefty gantry or 'sheerlegs' type crane, which also came in handy for changing wheelsets on internal user wagons. Cranes are discussed in more detail below. With any steam locomotive there are a standard set of facilities required. Usually there was a shed of some kind in which the loco could be oiled and prepared ready for use. There would of course be a coaling stage, usually a raised platform, possibly with a light crane to help load the coal. Water would be provided from a simple tank, perhaps a redundant boiler or some such, supported above the height of the loco, often on a wooden structure. Close by the coaling stage would be an ash-pit into which the burnt ashes from the loco could be emptied. Where the locomotives had inside cylinders (more common with ex railway company locos, rare on purpose built industrials) there would need to be an inspection pit to allow servicing of the cylinders and motion under the loco. Pola offer a stone-built two-road loco shed with attached workshop but you can make something equally plausible and requiring less room from card.