I want to model a coal trestle in an industry. It would only hold one car at a time and I’m thinking I can have part of the trestle base lower than ground level and create sort of a pit to reduce the needed incline. How do I measure how long an incline has to be? I’m modeling HO. Thanks.
Grade = rise/run. Or, for you, Run = rise/grade Say you need a deck height of 5" over the tracks or roadway below the trestle. You know you only want a modest grade, say 2%, written as 0.02 in decimal. So, you divide the 5" by 0.02, and you get 250, which is in the same units you introduced, inches. To go from any existing track level at no grade to a point 5" higher on a grade of 2%, you need a length of 250"
-Crandell
Thanks very much Crandell, that is what I needed.
The typical prototypical grade for a facility like that would usually be in the neighborhood of 4%, but in most modeling situations this results in a ramp length too long for the space available. Model locos should be able to push at least one or two cars up a grade like 6% or a bit more, so that could be an option. In any case, be sure to allow for vertical transition curves between grade changes or you’ll have problems with loco traction, hang-ups on the rails, couplers completely mismatching, etc.
Mark
Often the best solution is to have the base of the industry well below the general track elevation so little if any climb is needed to reach the top of the coal dump.
Mark
IE: Dig a hole. A BIG hole. did I menation it needs to be a BIG HONKIN FREAKY SIZED hole? No? Well, good, cause it doesn’t. I;m just over exaggerating. but in all seriousness, it would be far easier to spliyt the difference, dig out the ground part or all the way, and only raise the track a little bit. A family car with coal or a dumptruck can climb a dirt road better than can a hopper car.
The measurement Crandell gave you is correct, but if you take 250/12(inches in one foot) you get a ramp that’s 20ft long.
Tain’t happening Magee. Mosr MRR grades are 2% your gonna need a 4 or 6% grade minimum, and you an go higher for MRRs. The coal dump for a local business on the NWR is adownhill, but across from it is an industry that rised almost 1.5 inches over 12 inches (approximately 2 50ft boxcars leave a bi on the end to clear the switch), whish is a 12.5% grade if my numbers are right (1.5/12) and the engines don’t mind much.
Small-town coal yards frequently had a trestle height just sufficient to walk around under, and moved the coal into delivery trucks with the kind of portable conveyor units that Walthers used to sell in three-packs.
At least one coal dealer in Port Washington, Long Island, didn’t even have a trestle. There was a shallow pit under an otherwise level siding, extended out far enough to one side that the portable conveyor’s pickup end didn’t foul the side of the car. Moving coal from car to truck involved a lot of manual labor with coal scoops and rakes. (It also involved some rather colorful language, which is why my mother hustled me away from the scene.)
Chuck (Modeling Central Japan in September, 1964)
Thanks very much for the additional replies. I didn’t describe it very well in my original note but I am planning a pit of sorts that the trestle would run over in order to minimize the grade. The business in question is an older paper mill and I would only be dropping off one hopper at at time so between the pit and a steeper grade, I’m sure I can fit it in. I understand the concept of the transition to flat and I’ll have to read more about how to apply that. I was thinking about using the Woodland Scenics risers to help set it up.
In calculating the balance in my checkbook I’m calculating the rate of decline!
I’m sure it was back in the mid-'60s there was an article in one of the hobby mags about constructing an urban coal facility using antiquated hoppers converted to coal bins and an elevated trestle to facilitate unloading. Such a structure would, of course, be out-of-date on my now-era Seaboard and Western Virginia Railway–unless I decided to model it as an abandoned industry, of course–but would have credence in the trainsition-era and such a model would probably grace my layout were I to revert to that modeling-era.
If memory serves me the trestle leading up from the lead was built on a rather steep incline, maybe even as steep as 5%, because this facitlity was hardly large enough to accomodate more than one hopper at a time.
I believe this is something that you’re looking to do.
This needed very little ramp to reach the height needed for the depressed coal “re loading” transfer. The total rail to lower base is just a bit over 2 1/2" Worked out well, not completly finished in the pic.Just ignore some of that forground structure and loco on the asphalt. Work in progress during the pic.
That is exactly what I’m describing. I’m think that if the coal is dumped into a pit of sorts, I could do a fairly short ramp. Thanks.