hominamadFinally, there is an option to switch to a track that begins a 2.7% climb that ends up being 4" high by the time it crosses over the first rack. I can even make that 5" if I want but it will be a grade of about 3.7%.
Your diagram appears to show your grade beginning at 2.7% directly at the connection to the turnout. This type of "hockey stick" grade transition is not buildable as drawn, unfortunately. For most reliability, grades should not change within a turnout or immediately at the end of a turnout.
For reliable operation, you need at least a car length of level track after the turnout and then some car lengths of transition from level to grade, depending on how steep is the grade. Like this:
So your actual grade will be significantly shorter, and thus steeper, than your calculations It doesn't necessarily mean that it will ultimately be unworkable for short trains of short cars, but you'll need more careful calculations and some care in construction.
Remember also the increased effective grade of the tight 18" curves from friction: 32/R or 32/18=1.7% effective grade added to your nominal grade. That adds up fast.
And as Paul noted, the location you have suggested as a yard will not really allow enough length to be usable as drawn. Once you consider clearances from adjacent tracks, your industry spurs might be shorter than you think in terms of usable length, as well.
Best of luck.
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Just like in the real world, changes from one level of operation up against gravity to another level, such as over a hill on a railroad, require phenomenal amounts of energy. While rail transport is second only to water-based transport in terms of efficiency, lakes and seas are essentially 'flat', whereas railroads have to negotiate grades and curves all the time.
Take another look at Byron's diagramme. Those transitions.
Suppose it takes only 600 hp to pull a trailing tonnage along level track @ 30 mph. For every half-percent rise in grade, the horsepower requirement more than triples. So, if you nicely transition from level running to a very gentle 1% grade, you will need nearly 3700 hp (!!) to maintain the same speed. And that's only if your engine can apply suffficient traction at the wheels to maintain its adhesion. If it is too light, you'll slip supplying the tire surfaces on steel rails with that much horsepower. Slipping means "No longer going 30 mph, and approaching zero very quickly." Better hope your brakes work!
My point is that it works the same way for our scale locomotives. The physics scales pretty well, all things being equal.
Another point, and this is about grades. Even if storming up grades won't be a problem, or crawling, because you have tons of tractive effort on the head end, the steeper a grade gets, the longer the transitions into and out of them must be. Think about it. With a mere half-a-percent change, you could almost make a kink and your lcomotives are unlikely to loose their footing. Now imagine going from level to 3%. That's one heckuva kink! So, you fashion a vertical curve at the bottom of the grade to 'ease' your locomotives up into the grade in such a way that the couplers behind them don't disengage and so that all wheels providing traction can continue to enjoy adhesion on the rail heads. But, just as you must do this at the bottom, so you must leave the rising path gradually at the top when you want to return to level. The big question is, how do you fit what would justifiably be called a reasonable vertical curve with all the desired properties into the same space you were planning...the same length of grade? If your grade is steep, your transitions will have to be longer for the 'easing' part, and that severely impacts the actual change of elevation between those longer vertical curves.
In conclusion, the steep incline on any railroad, real-world or scaled, is a distinct and severe impediment. They require careful engineering, gobs of horsepower, and tons of room if you want to minimize the damage or energy requirements they are wont to impose on the trains.
Good points about the grades. I'm going to tweak the plan to allow for vertical easements and then see what it looks like. Is the grade on the Virginian handled better than what I have?
It seems in a 4x8 or even 5x9 or 5x10, doing anything with grades high enough for crossing over is difficult and not recommended.
So it would seem. There is a possible solution, though. You split the difference between the two levels. Instead of making the one track rise and fall again, doing all the changing, why not make the nether one shoulder some of the obligation for clearance between the two? Make the topmost track do a 2% rise and fall while the track over which is passes does the opposite. You get your 4% separation over the same distance, but with grades half that oppressive.
Crandell
hominamadGood points about the grades. I'm going to tweak the plan to allow for vertical easements and then see what it looks like. Is the grade on the Virginian handled better than what I have?
Note that the Virginian grade is much longer than yours before crossing over. This allows the chance for a longer run to reach the desired elevation, lessening the grade. There are some other issues in the way the grades affect the industries (cars will tend to roll out of the big mine based on the grade of the branch, for example), but those were probably dealt with in construction.
Simply double-tracking the outside oval of the Virginian might give you a place to start in 5X9 or 5X10. But note that concentric 22" and 24" curves may not give enough clearance. 2.5" difference would probably be a better safety margin with a wider variety of equipment.
hominamadIt seems in a 4x8 or even 5x9 or 5x10, doing anything with grades high enough for crossing over is difficult and not recommended.
I personally didn't say that it wasn't recommended, only that one must be realistic about what may be accomplished. Reliable grades do require care in design and construction Unfortunately, the majority of published HO 4X8 tracks plans are overly optimistic in the grades they quote.
If planned and built with care, grades can work on smaller track plans, but they may limit the length of trains and cars that may run on them reliably.
Byron
hominamadThe outer loop is 24" radius and would serve as a small passenger line. The next loop inside that is a 22" radius which will connect in one or two places with the outer loop and could be a mixed passenger/freight line.
Here we have an issue that might be overlooked easily. For most newbies operating is just that, having two trains orbiting at the very same time, without any interaction. Also for your sons this will become boring pretty soon, unless some exitement is designed in. IMHO dads modelrailroad is quite different from the one your boys will love best.
On normal double track railroads freight and passenger trains both run in both directions. Some form of staging could make that possible, just as the staging addition on the MR-Virginian. Wayfreight and or yard operation is usually part of the fun on a lot of "adult-layouts". Like a train from staging to a highlevel terminal and back, whether it's a freight only, a mixed train or a mine run.
BTW on small layouts trains usually are pretty short; Byron Henderson (Cuyama) made a very wise remark. The steep grades needed on the branch will limit the length of both cars and trains. An engine with a 60 ft coach and a combine is quite different from a train with 5 full body 85 ft long passenger cars in tow. The first might very well be doing fine on both the main and the branch. Those longer cars require more clearance as well, as noted already by Cuyama.
Smile
Paul