If you are running short trains you might get away with it. Generally it is best to minimize grades (just like real life) as much as possible. The maximum grade I have ever used is on my present layout - it's 2.9% and I can pull a 22 car train up the grade with two six axle diesels. I haven't tested to see what the limit is but that is within my operational needs. I had a garage layout many years ago with a 2.5% grade and two Atlas GP7's would barely pull a 20 car train up that grade and the wheels would slip if I gunned it. They were smaller, lighter engines than the SD45's I'm using pull the 22 car train up the 2.9% so size/weight/number of engines is a factor too.
If you can manage with 3%, thats what I would choose. And yes easements on curves and grade changes are a really good idea. I used easements on my grades - which were stretches of track at intermediate grades - like stating out at 0.5, then 1, the 1.5, then 2.0 etc., you get the idea.
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AndreAnyone have a 4% grade on their layout and does it work fine? im not bringing huge loads up it (most 10 cars).
Transitions at the top and bottom of the grade will be important.
Any curves in the grade will add substantially to the effective grade due to friction.
At 4%, what you can move will depend a lot on the loco and the cars.
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A fairly easy way to get a smooth transition at the top and bottom is to stagger layers 1% or 2% inclines.
For example, on my layout, I start with a 2% incline. Halfway up the incline, I add another 2% on top, so the incline is now a full 4%. When the first incline ends (halfway up the second incline), I add the next 2% incline to maintain the 4% grade. Then, conveniently, when you're reaching the top of your slope, you're left with 12 inches of 2% grade again to ease the transition to flat.
A full size 2ft 2% incline rises half an inch, so after each incline ends, you can put in a layer of EPS to support the next incline.
This method ends up being the same price as a 4% incline is about twice the cost of two 2%s, and although my description might sound convoluted, it was pretty easy to do.
4% is fine as long as you transition at the top and bottom. To transition at the bottom is real easy as you can do it with your cork stretched, extra calk under the cork at the transition will fill the gap. At the top however you need to trim the foam to get a good transition, not hard but takes time to get it right. As long as you are only going up about 4", your 10 car trains will have no problem with most engines. The thing that alot of people get hung up about is trying to do prototypical with model trains. I garentee you that if real railroads could easly pull up 4% grades, they would do it instead of 2% gerneral max.
It is sort of the same rationale as is applied to minimum radius: for best operation, one uses the larger radius and the lesser grade. Clearly, there are plenty of prototypical examples of grades in the 4% range. I had a 4% grade on a small switching layout back in apartment-living days, but only had about three cars per train.
I had a 2.86% grade on my larger basement grade (not sure how I got to 2.86, but that is what it calculated out to). Any run-aways are going to the bottom of that grade, so insure that there is some protection on the outside of any curve at the bottom of the grade to prevent any run-aways from tumbling to the floor. Also, if there is any passing track or run-around on the grade, you will need some sort of "hill-holder" mechanism to keep things from running away.
Overall, there have been many small model railroads that successfully use 4%, and the use of a smooth transition into that grade as LION suggests is very important for reliability.
Bill
If you're using WS risers under all the track, keep in mind you might be able to have the track going under the higher track go down, allowing a less steep grade on the upper track. So say you have a track crossing another track on a bridge, and it takes a 4% grade to get the top track high enough to clear the lower track. If you put a section of 3% grade going down on the lower track, even if it just lowers it an inch, it might allow you to reduce the upper track's grade to 3%.
Anyway, 4% is generally the maximum grade used on a model railroad outside of say a logging railroad. Keep in mind on a 4% grade, your engine's pulling ability may only be 20% of what it would be on level track.
It all depends on the equipment you are running How long are the locomotives. Do you have smooth transitions at the ends of the incline. Long cars may uncoupple if there is a high-low transition.
LION has built some pretty steep inclines on the layout of him. Locomotives had no problems pulling upto 6 85' pax cars up. I switched to subway ewuipment and they coud not amke the grade, I had to putll it out and make a helix.
If you have not the room for a longer inclineyou would hardly have rom for a helix.
TRY IT! If it works you are good, if not you rip it ouyt and try something else. LION has ever measured the inclines of him... It works or it gets pulled out and we try again.
ROAR
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I recently got a woodland scenics 4% foam incline and i was testing it today and wondering if i should go for a lesser grade. I dont have much space which is why i figured 4% it fits almost perfectly but i could probably squeeze in a 3%. Anyone have a 4% grade on their layout and does it work fine? im not bringing huge loads up it (most 10 cars). Any help would be greatly appreciated
Thanks everyone
Andre