varies

I can't give a definitive answer, but the need will vary a lot depending on the season and weather.  Wet or icy rails will need more sand, and wet leaves can also be treacherous.  Heavier loads--perhaps during harvest season--will mean heavier trains and might need more sand.

Sand

Is it dry or rainy?  Is it uphill, down hill or flat?  Does the engine do a lot of switching?  Does the engine do a lot  of stopping and starting?

Generally the sand would last at least one trip and probably several.

An SD40 has about 56 cu ft of sand capacity, so a steamer would have somewhere in the 40-60 cu ft capacity range.

"I would like to schedule the

You might look at photos of a terminal similar in size and operations as your modeled scene to see how big the sand storage facility  is and if any sand cars are shown on the delivery track. You could also divide the capacity of your covered hoppers by 56 cu ft to see how many engines a hopper load could fill up then use your timetable to figure out how many days that would last? .......DaveB

OK. I understand this is a

OK. I understand this is a very vague question and elusive answer. Here's what I can tell you.

I model Western Maryland at the end of the steam era in Fall 1954. Basically the Thomas Subdivision which is a very steep and winding line up to 2.75% grades. Engines are very heavy 2-8-0's in H-8 and H-9 classes hauling 10 2 bay hoppers each with trains being up to 70-80 cars with helpers and pushers on the rear and mid-train.

I have no idea what the sand dome capacity might be for these engines. If I had that information it would let me work up the answer I need. Looking at photos and videos I do know they used sand liberally. 

Thanks,

Roger Huber

OK. I understand this is a

OK. I understand this is a very vague question and elusive answer. Here's what I can tell you.

I model Western Maryland at the end of the steam era in Fall 1954. Basically the Thomas Subdivision which is a very steep and winding line up to 2.75% grades. Engines are very heavy 2-8-0's in H-8 and H-9 classes hauling 10 2 bay hoppers each with trains being up to 70-80 cars with helpers and pushers on the rear and mid-train.

I have no idea what the sand dome capacity might be for these engines. If I had that information it would let me work up the answer I need. Looking at photos and videos I do know they used sand liberally. 

Thanks,

Roger Huber

I'd say rule #1 applies

Some very informative answers.  Rule #1- your railroad your rules.  Whatever seems appropriate to your operations.

Vague answer I know, but trial and error during your ops may be the best answer?

http://themodelrailwayshow.co

http://themodelrailwayshow.com/LayoutDesign/?p=3444

Wing it

And really that has no bearing on the answer you want, since sand capacity isn't what you are looking for.  What your are looking for is sand USAGE.  If an engine has a 60 cu ft dome and another has a 20 cu ft dome, but both only use 10 cu ft per trip, the dome size doesn't matter.

1954, sand would probably be delivered in 30-40 ton boxcars and shoveled out of the cars.  How detailed do you want to be vs.  what you are actually going to do on your layout?  Lets say they get a 40 ton boxcar every other day.  Your op sessions represent 8 hr shifts and you have a formal op session once a month. 2 days = 6 shifts = 6 months of sessions.  Are you really going to spot a car of sand twice a year?

If the answer is you would want to switch teh sand track more frequently, then sand usage doesn't matter, do what looks right.  Are they going to spot 10 cars every shift?  Probably not.  Might they spot one car every other shift? That sounds more reasonable.

Heres another way to look at it.  Get a picture of the sand facility.  How big is the storage?  They are going to store several days to a week of sand because they have to bridge variability in getting sand to the facility.  If they have a sand storage that is 10 ft wide, 30 ft long and 6 ft high, that's about 2 cars of sand.  So 2 cars of sand will last them about 3 days to a week.  That will give you the rough frequency.