Maximum prototypical "decline grade

Model Railroader Layouts and layout building
1

Hi everyone

limited to a 4’ x 8’ HO layout right now and I am very tempted to put an 3% incline in which will tack up a 12’ run using the curve and straight away.

My questiono are:

What is the maximum prototypical grade that I should use as a guideline?

Can I descend prom the high point in 4’?

Will my HO locomotives (steam and diesel) handle it?

Passenger trains will have a consist of 3-5 cars and freight trains will have a maximum consist of 8-9 cars.

Could not find a definite answer doing a search so I came back to the forums to hopefully get some guidance.

2

Have you considered a helix?

http://mrr.trains.com/how-to/track-planning-operation/2010/09/construct-a--simple-and-reliable-helix

3

There’s quite a bit to unpack in your post.

A 12’ run at 3% gives you a railhead elevation of about 4¼”. Does your calculated 12’ run allow for transitions from level-to-grade and back? If not, the actual run will be shorter and the grade will be higher.

Note that changes in grade within or exactly at a turnout often create reliability problems. In an earlier post you were talking about #8 turnouts – those are especially long and may restrict where your grades can start and end (if #8s are still in your plans).

Also, if much of your grade is on curves, the effective grade will be steeper by a factor of 32/R (this is for HO, R being the radius). If you have 20” radius curves, for example, that yields 1.6% added to your nominal grade (at least through the curves). That’s getting pretty steep.

Prototype grades don’t often apply directly to the model since the physics are different, particularly through our extremely tight model curves. 3% grades or a little less usually work fine on the model, somewhat steeper grades can also work, but care must be taken with the transitions from level-to-grade and back.

So you are going to run trains in only one direction? 4¼” inch descent in 48” run is nearly a 9% grade. That may be too steep for trains to operate downgrade

4

Since the Original Poster is talking about a 4X8, that would limit the radius of a helix to something like 22”. Multi-turn helixes built that tight in HO have typically been found to be quite unreliable. Not to mention that the helix would take up half his layout.

5

depends on your particular locomotive and the weight (not number) of cars in the train.

6

Logging railroads, the real world (prototype) ones would often run grades between 3-7%, with small stretches even steeper. Which prototype would you like to have as an example on your layout?

Main lines on the Class 1 rails have gone up into the 3.5% range when there was no other solution, even a tad steeper. It meant helper engines stationed nearby permanently unless the route changed.

You don’t have room for a helix unless you are willing to build it in an adjacent space/room and go through the walls.

As Greg says, the answer to whether or not a train will be able to handle steep grades (“steep” being relative) is entirely dependent on the grade and the capacity of the drive in the toy loco to lift itself and its trailing ‘tonnage’. You need to do some objective experimentation by mocking up some known grades and seeing how your loco(s) do with what you want trailing behind them. When you sense slippage or stalling, you have three choices, including a combination of these:

a. lose ‘tonnage’; or

b. lose steepness (reduce the height attained by the grade).

7

c. add weight to the locomotive

8

It’s a thought, Greg, yes. Practically, it’s going to be a no-go to someone asking about how steep a grade his trains can take.

9

On a 4’x8’, there’s room enough to come off the outside of an oval where the straight track begins, then have it climb enough by the time it gets to the opposite side of the layout where the other straight track is, then cross over the layout and the original turnout for the beginning of the grade, then descend around the opposite end and rejoin the oval.
This will, of course, reverse the train’s direction of travel.
It’s also possible to create a loop inside the original oval to re-reverse the train.
This was what my original layout was many years ago. For good operation, your cars should be no longer than 40’, especially on that inside loop, and the relatively low clearance will limit car height - on that layout, an Athearn 200 ton wreck crane needed to have its stack shortened to clear the bridges which passed over the main oval. I’d post a photo, but I can’t find the one of which I’m thinking.
My four Globe F-units (one with one powered Lindsay truck and three dummies) could haul all of my freight cars (nine or 10 as I recall) without difficulty, and that was before the days of Delrin trucks.

Don’t worry too much about prototypical grades, as the curves on a 4’x8’ aren’t especially prototypical either. [swg]

Wayne

10

Hello all,

I too am limited to a 4’x8’ pike.

My pike models a freelance coal branch set in the late '70’s early '80’s.

I have a fleet of 1970’s vintage Tyco operating 34-foot hoppers that have been upgraded to Kadee couplers and trucks.

A 3% grade takes these cars up to an unloading platform, on a siding, and the empties are shuttled down a spiral trestle back down to the mainline.

I used sectional track on the incline. It is an asymmetrical curve made up of 22-inch to 18-inch radii track with a 3-inch straight section between the curves.

The grade is built from Woodland Scenics Incline/Decline set with foam roadbed. Using the Woodland Scenics Incline/Decline set allows the incline to follow the contours of the sectional track.

This incline begins on the 8-foot side; 30-inches from the 4-foot end, and terminates 24-inches from that same end of the pike on the opposite side at an elevation of 3-inches.

It transitions to a 4-foot long, 4-1/2-inches wide, elevated section with the unloading siding.

At the end of this elevated straight section there is a short section of curved track to an 18-inch bridge that spans the mainline below to the spiral trestle.

The spiral is made from 15-inch radius sectional track with 2-inch straight sections every quarter of the spiral.

The bents are a plastic, commercially available, riser set. There are two of each height in the set. To provide a constant grade the identical upslope bent is shimmed.

The bents are tied together with cross bracing to form a curved trestle.

A PECO #2 turnout ties this back into the mainline.

The coal cut of 6 hoppers is pushed up the incline with a consist of a GP30 and a GP30-B with another GP30 on the head-end which is cut at the top of the grade.

The empty hoppers are then shuttled down the trestle by the head-end GP30 to the mainline.

Many participants in this forum have comm

11

Steepest line-haul railroad grade in the USA was 5.89% at Madison Hill:

http://oldmadison.com/madview2.html

http://indianarailroads.org/board/index.php?topic=690.0

https://www.nps.gov/nr/travel/madison/Madison_Railroad_Incline_Cut.html

12

Yes, but Madison used specially equipped locos and some very specific operating practices. There was a story in Classic Trains from a guy who worked on that line about the time the loco came back fromt he shops with the special braking system disconnected, or else the subbed in another loc thinkign it didn;t matter, I forget exactly, however it was a rather eventful trip down that hill without the usual braking.

Frankly I would not bother with over and under elevation changes on a 4x8, the grades are excessive to do so and due to the limited space to have straight runs to have the grades. It also limits the flat areas where you can put sidings. I assume the reference to #8 turnouts was for a different size layout, because #8’s are next to useless on a 4x8, especially with continuous running. No loco that needs a#8 will be able to turn on the 22" radius curves that are needed for a 4x8. Unless you are modeling one end of a junction or a siding, but then there would be no grade issues.

–Randy

13

A 1% grade is better than a 3% grade.

I once read the railroads don’t like anything more than a 3% grade and even 3% is pushing it.

The Southern Pacific had a 3% grade near Roseville CA.

14

This sounds interesting. Do you have any pictures?

Mike.

15

Hello all,

Thank you for your interest.

Mike, I do have photos of the build however I refuse to participate in a photo hosting site, which seems to be the only way to post photos or diagrams on this forum.

Hope this helps.

16

It will not work for everyone. It works because you use a very specific set of equipment that will work for those conditions. Over a broader range of equipment, your track plan becomes very limiting, possibly unworkable.

17

Hello all,

Yes…

That’s what prototypical railroads do as well.

If you are limited to a specific set of constraints then you work within those constraints.

That’s what the OP was seeking advice on; a specific situation with a specific set of constraints to achieve a specific outcome.

I agree…

Again, see my signature.

18

And the constraints that you have will not work for his desired outcome: “3-5 car passenger trains” (and freight). Granted 22" radius is pushing it as it is (Walthers heavyweights need >24" or greater to operate (without extreme modification). Rapido Osgood Bradley cars are reliable on 24" radius. I have not tried them on 22". If the OP can find Athearn BB cars they will likely work for 22".

As an aside and somewhat unrelated: if you put more prototypical couplers on the cars, such that the diaphragms contact slightly, you need >34" radius (as I found out to my dismay, I will be installing some slightly extended shanks and retesting (have a couple of options).

I saw it, so did everyone else. And the point I am trying to make is that the trackplan would likely (I didnt say it was impossible) not work with other equipment.

Just out of curiosity, are you using standard Kadee trucks and couplers or Kadee talgo trucks?