We’re about to start “serious” operating sessions on my friend’s railroad. His railroad is patterned after the Clinchfield; complete with a branch to Moss and its coal cleaning plant. All coal on this railroad will go to Moss for cleaning and grading before being shipped to the customer - just as it did on the Clinchfield.
Since there was no mine at Moss (only that coal cleaning plant), what was the ratio of empty and loaded hoppers to and from Moss?
I’m thinking that a given tonnage of “raw” coal headed to Moss would have required more hoppers than the cleaned, graded coal leaving Moss. Even ignoring the fact that the cleaning removed a good deal of slate and other undesirable rock from the coal, the raw coal would have been in larger pieces and would therefore not have filled a hopper as well - there would have been more air in every load. The cleaned, graded coal would be in smaller, more uniform pieces and would use the cubic capacity of a hopper more efficiently.
Anybody able to give us some idea of how many empties would be generated at Moss for any given number of loads arriving there?
Good questions. It’s all part of the science of car distributiion.
Many railroads issue documents called “Coal Car Distribution and Rating Bulletins,” aka “Rating Books.” These booklets break out mines by district and tell how cars are to be distributed to them and also how many cars were loaded over a particular time period. You can figure out the ratio based on those #s and adapt them to your model operation. I am sure Clinchfield had a similar system. It should not be too hard to find a document you need and make the necessary calculations. In any cae, you’re gonna need lots of cars.
I dug up an old N&W rating book in my stack of stuff. In 1973 they listed 10 Clinchfield Coal properties including Moss 2, 3, 3A, and 3 CD.
BTW, sometimes, clean coal can be heavier than you think because of the water involved in cleaning it. Lots of fun in the winter when it freezes.
I hear that (I may be a Texan now but I was born and raised in Western Pennsylvania…until I was 10, I thought anything but a hopper was special equipment).
My suggestion that fewer hoppers would be needed for clean coal than for raw coal is based on cubic capacity rather than weight. Few hoppers were ever loaded to their weight capacity until fairly recent times. Coal, particularly bituminous, just isn’t that heavy. 100 ton cars today do indeed haul right around 100 tons - frequently more - but they have a much higher cubic capacity than earlier hoppers. You would have had a hard time getting 50 tons of coal in a 50 ton hopper; there just wasn’t room for it.
You mean there’s something other than coal cars? I’ve heard rumors about those things (LOL).
The winter of 1976-77 (don’t know where you were for that one) stands out as being an especially bad one for frozen loads. IIRC, C&O did not have thawing facilities at Newport News then so a lot of “field expediency” was used to get coal out of cars. Scary stuff.
How are you modeling the cleaning plant? What era and what kinds of cars will you use? Plant switcher or road power?
Yeah. I remember getting excited when a PRR mine run had a box car ahead of all of the hoppers.
Don’t remember where I was in '76-'77 but it was probably one of many winters that I spent commuting to downtown Pittsburgh and wondering if I would ever get warm again. But be careful what you wish for: we’ve had more than 30 100+ degree days this summer in North Texas and no end in site.
The cleaning plant has already been built; it’s a fairly typical large, corrugated metal mine building spanning three tracks with covered conveyor beltways leading from a two-track dump pit and to a spoil loading tipple (all of the slate and assorted other junk was hauled out of Moss and dumped on the banks of local streams to keep them from undercutting the track). I don’t know if it’s at all accurate or not but it captures the spirit. The era is kind of hazy: the power is 99% late steam with mostly large Mallets running around and a few Mikes. Hoppers are mostly Accurail 55 ton USRA cars in various versions. Like the Clinchfield; older, smaller power - Mikes and maybe a Consolidation - will handle the switching jobs.
It’s not an easy answer unless you’d been there. To summarize the 729 pages of my AIME text “Coal Preparation” of 1943, anywhere between a 3 and 20% refuse ratio was seen in practice – that is, the percent of coal coming in that did not end up in the refuse pond. It depended upon the plant design, the characteristics of the coal that day (every seam was different), a particular customer’s requirements, what the coal market was doing at that point in time, and how well the plant was running that day. One day the plant might run a particular coal to a 92% recovery rate of cleaned coal and a month later might find it more economical to run to an 89% rate. Plants also changed quite a bit over the years as new machinery was brought in to replace ou
I suspect you’re comparing Eastern vs Western practices when you ought to be comparing eras. Fifty years ago, we didn’t have the materials that would have made 100 ton hoppers economical or, in most cases, the track structure that would support them. C&O and VGN did have what they called “battleship” gondolas that were 100 or 110 ton cars but remember that they rode on expensive 6-wheel trucks and were hardly ever allowed off their home rails (nobody else wanted to handle them either).
I would but this coal cleaning operation is on a friend’s layout and I don’t have any pictures. More importantly, it hasn’t been scenically finished yet and my friend might just become a former friend if I published pictures of it as it now exists. You’ll just have to rely on my 10-7-06 post and use your imagination. Sorry.
Seems the only real answer to my initial question on this topic is a big fat “IT DEPENDS”. OK, I guess we can live with that. One less compromise to worry about.
No, actually I was thinking about the 1940s. Having spent my career in railroading in almost every department except legal I’m aware of load limits, or, should I say, the ways in which they limit.