Realizing colour is more a function of local geography more than anything else. My question is more of a question of what colour have you found looks best in a Yard/Locomotive facility?
I’m opting for black but is this a common colour in the Steam era yard or does it matter?
Fergie
Because my road is Southwest desert, I’m attempting a look simular to the Barstow yard, flat yellow sand, Found fine artistic sand at a craft store that is a good sand color.
With almost any color of ballast, I paint a thinned wash of grimy black between the rails. Diesels leak and steamers, whether oil or coal, leave residue. With fuel facilities, there’s always a little mess, EPA or not.
Loco yards are different from almost all other yards… generically black… but study pictires for your location/road and era. A new yard or a yard with recent maintenance will look difernt from an old yard.
Locos shouldn’t leak whether steammor diesel. Lubricants don’t help bearings if they’ve spilled on the track and create slip hazards. Fuel is supposed to drive the train not decorate the track. One thing that would colour an area in steam days is ash… different coals produce different ashes. Despite all that whole yards or areas within them will accumulate mess over time. Modern facilities are extremely careful about mess because of the environment and to reduce hazards to staff.
You can’t get a shining loco out of a muck swamp.
Other yards… a lot of the same applies… the big difference would be where a yard handled large amounts of anything producing spillage… especially dust. Grain produces dust, so does sand, coal, fertiliser. colours can vary from black to white. the product is supposed to travel not stay behind though… it often gets weighed at both ends… so losses have to be accounted for. A yard doesn’t want to be buried… it impairs working. it would be cleaned up periodically. Spillage, especially of powders, can block drainage… causing puddles and problems (look at where puddles occur in photos of yards… and damage from wheels (of trucks) in bad surfaces… also tyre trails from puddles.
Both yards…
When drainage gets bad/blocked ties rot easily and the track can set solid or pump up and down - check videos. Spikes can break out, get sheered off or get yanked loose. This can allow the road to spread. SO maintenance is usually kep up… at least as traffic pays for. One thing no-one wants is a car or loco in the dirt… it’s dangerous, time consuming and potentially damaging to both the car and load (or loco). So both balast and ties get regular maintenance in a yard… often between work on the main tracks. Frequently i
Since you specified engine service yard, I immediately surmised coal burning steam and thought ‘cinders.’ After all, steam loco BMs had to be used somewhere. Of course in this non-steam era that’s no longer valid, so the fall back position is check your prototype.
Yards are usually pretty level, even when the ballast is maintained in top-line condition. The surface has to be safe for yard men to walk on while they tend to their duties. Also, spills are cleaned up and shipped to the consignee if at all possible. That’s a lot easier than settling lawsuits or paying damages for missing lading. Thus, there might be a few black diamonds marking the spot of a mishap with a loaded hopper, but not heaps of them.
Poorly maintained yards can have embargoed tracks which have sunk out of sight in the mud that used to be ballast, and even have considerable vegetation (up to good size bushes) growing among the tracks - and even between the rails of embargoed tracks. Better maintained (and busier) yards are usually cleaner, but you can probably count the yards in the world that are completely weed-free on the fingers of your foot.
Chuck
Maybe I should have posted this first

Wow!!! You guys made some excellent points, Thanks!
As you can see there is a engine service track as well as the main yard, which will be used to handle coal, Gypsum, general merchandise and ore. So I think I’ll go with heavy deposits of coal with white streaking.
Nice pics! Anywhoo, I usually use black, and then mix in a little brown and red, with some grimy black detail. I might eventually get my RR looking good enough and complete enough to post some pictures, but I doubt it. Good luck!
During the steam era, yards were typically ballasted with cinders. Now adays, yards are likely as not to be ballasted the same as the mains.
Nick
i think it depends on the railroad your modeling.