# A question about slope



## CliffyJ (Apr 29, 2009)

I've concluded, from reading several articles, that a 2% slope is the max that one should plan for in a new layout. But for tight spaces, where tracks (and their roadbed structures, at least in tunnels where bridges aren't involved) need to cross one another, such a slope can at times be difficult to accommodate.

So for a short-train line like the one I'm planning (based on the V&T; say, 10 cars max), is this still a "good" number? Or does a 2% grade reflect other things, e.g., limitations for a main line system, dealing with many more cars to haul? Or, maybe it reflects limitations in switch behavior (e.g., asking for derailments)? Or...?

In short, where does this 2% ideal (if it is) max grade come from, and what are the variables that might bring it "safely" up to, say, 3%?

Thanks much,
Cliff


----------



## lownote (Jan 3, 2008)

You can get away with much more depending on what you want to run. I was forced to have a grade of over 5% on my layout. It works, but I realy dislike it--it limits the length of trains you can run a lot, and it just doesn't look right with what we generally run, which is more mainline/standard gage


----------



## Greg Elmassian (Jan 3, 2008)

Let me give you a calibration on slope: 

I have one place I have a 5.5% grade, you always go down this grade, but George Schreyer tried going up with his SD45, which will pull 45 cars on the flat. 

It pulled about 10 with wheel slip, and a practical limit would probably be 7. (George, correct me if I remembered the numbers wrong). 

So from 45 cars to 7 with a 5.5% grade. 

Spend more time getting the grade down to 3% max, you will thank me for it... 

The mainline has a 3.4% grade, and it takes more than a Mikado to pull 6 Aristo heavyweights up it. 

Regards, Greg


----------



## Randy Stone (Jan 2, 2008)

Another thing to consider when putting in a grade/slope of more than 2% is the life of the locomotive you are running. A Bachmann 2-4-2 is pretty weak running on a level track. Put it to climbing much of any grade continuosly with out any cars in tow and you can expect the gearbox to fail. If you run any locomotives with traction tires, you run the risk of tearing up the gearbox on a steep grade pulling too many frt or passenger cars, where a locomotive with all metal wheels will just slip. Just like the real locos, if Geo had 6 or 7 SD45s, he might well have been able to pull 45 frt cars up the 5.5% grade. 

So, build what you have to by your restrictions, just know that anything over 2% is likely to give you a migraines. 

Randy


----------



## aceinspp (Jan 2, 2008)

Adding any type of grade to a RR brings undo stress to various locos. Know what your loco can handle and build accordingly . Defiantly avoid if possible any thing over a 3% grade. Later RJD


----------



## Mike Reilley (Jan 2, 2008)

This also depends on the kind of engines you want to run. Diesels and geared steam locos handle grades better than rod engines. This is because all wheels are powered and they're spread out over the full length of the engine. Shay's and Heisler's and such were designed for steep grades and tight curves...and are notoriously slow. On the other hand...big rod engines are fast...but don't handle tight curves or steep grades as well. If the engine has an equalized chassis...it will handle grades better than engines without sprung drive wheels.


----------



## Richard Smith (Jan 2, 2008)

Cliff, 

2% - 2.5% is close to the limit of grade if you want hands-off running, with the possible exception of Shays or other geared engines. With 2% or slightly more you can just set the throttle and for most locomotives let 'em run. Once you reach 3% or so throttle adjustment becomes necessary as your train progresses to prevent racehorse runs on the downgrade and stalling on the upgrade. If you like to operate instead of just watching then steeper grades can be fun and challenging. Even then I would hold grades to between 3% and 4%. This is from a model perspective. A 10 car train as you state you wish to run should do fine under these conditions. 

Prototype: Great effort is made to keep grades down to 1% whenever possible. For mainline railroads 2% is a considerable grade and 3% quite severe usually requiring helpers in the older, steam days especially. Remember that a mainline train might have in the neighborhood of a hundred cars. 

Shortlines and branchlines were usually built to provide service to a very specific area or commodity and were thus presented with fewer options as to right of way choices. This could mean 4% or greater grades. The Colorado Midland Ry of the turn of the 20th century was a class I R.R. in its day and had some horrendous 4.5% mainline grades. Trains were mostly pulled with 4-6-0's and 2-8-0's were used as helpers. A 30 car freight could often take 3 or 4 engines to make these grades. The Southern Ry. had one branch where the grade exceeded 5% if I remember correctly which necessitated getting a running start and letting the back half of the train (still on the downgrade) push the front half (on the upgrade) up the hill. 

So while there were heavy grades in some circumstances, they were the exception rather than the rule. 

It has already been mentioned that heavy trains and/or heavy grades increase the wear and tear on your model locomotives just as they do on the prototype so take that into consideration also before setting your grades.


----------



## Al McEvoy (Jan 3, 2008)

Steep grades appear toy-like and look more like one is modeling a roller coaster instead of a real railway. All the advice given here is good - keep grades minimal - below 3% as much as possible with 2% as an ideal maximum target. One way to achieve this is to measure the actual clearance required for your rolling stock. Unless you are modeling in 1:20.3 scale (Fn3) you should only need approx. 8" to 9" over the railhead to reasonably clear any locos or rolling stock that I have ever seen. Add to that the thickness of the bridge or whatever supports you are planning for the overpass. Some may want more clearance for prototypical reasons but you are asking how to engineer an over-under situation into a small space.


----------



## Al Sauer (Jan 3, 2008)

This raises a question that I have been researching - what is the recommended vertical clearance for Fn3 - 1:20.3? I have a location right now that i have been able to just barely get to about 9.5 inches. I sure hope this is enough to clear bachmann boxcars and AMS passenger cars!

Thanks

Al


----------



## LocoLover (Jan 2, 2008)

Please don't tar and feather me for what I'm about to say about grades. I will say at the outset that it only applies to one prototypical logging railroad that I am aware of. According to the tour guide/announcer on our Cass tour, the Cass railroad at one time, had some areas with grades of a whopping 15%. According to this gentleman, there were a few of these, but they were not extended lengths, but only for short duration over very rough areas of terrain where they could not get them down to a lower percentage. He emphasized that this was far from ideal, and these areas could only be negotiated by the Shays. Even the Climaxes and Heislers could not negotiate these very steep grades. Again, in closing, let me reitterate, I am not advocating these types of grades on your layout, only pointing out their existance. 

Bill


----------



## Totalwrecker (Feb 26, 2009)

Posted By Al Sauer on 06/26/2009 2:33 PM
This raises a question that I have been researching - what is the recommended vertical clearance for Fn3 - 1:20.3? I have a location right now that i have been able to just barely get to about 9.5 inches. I sure hope this is enough to clear bachmann boxcars and AMS passenger cars!

Thanks

Al



Al. I can't give you a number, but check your locos they are usually taller than boxcars. Remember the roadbed of the upper track counts against you

Some will suggest taller for visiting equipment, but those are your call.

John


----------



## Greg Elmassian (Jan 3, 2008)

He wants to model a short line, not a logging railroad, so most comments are in that vein. 

Anything over 5% (in my opinion) needs geared locos, and those are logging locos. 

His short line would be rod locos normally. 

Regards, Greg


----------



## CliffyJ (Apr 29, 2009)

Thanks so much all; I'd certainly not considered all the issues, and it's great to have them all laid out here. Let's see if I have them right:
[*]Pulling capacity [*]Gearbox wear (never though of that...) [*]Unattended operation (esp. runaway downhill situations!) (never though of that either!) [*]Wheel slip [*]Additional prototypical factors [/list] I guess my main takaway is that I can now "safely" switch to 2.5% max in the design, which will indeed solve the particular problems I was running into. 

So thanks again!! 

Cliff

PS, unless it's already been done, this subject seems (to me at least) a good candidate for a GR article!


----------



## Bruce Chandler (Jan 2, 2008)

My short line runs with 4%+ grades. It would have been nice to have lower grades but my back yard wasn't as level as I thought. 

For operations, I typically limit my trains to no more than 5 cars plus a caboose. The Airwire equipped locos tend to need special attention on the down hill as they are prone to fast acceleration; the RCS equipped are not so noticeably affected. I haven't noticed any problem with wheel slip. 

If I were to run longer trains, I'd need a lot more cars. As it is, I'm a bit short of cars when operating with two trains in a day.


----------



## Totalwrecker (Feb 26, 2009)

Posted By CliffyJ on 06/28/2009 7:53 AM
Thanks so much all; I'd certainly not considered all the issues, and it's great to have them all laid out here. Let's see if I have them right:
[*]Pulling capacity [*]Gearbox wear (never though of that...) [*]Unattended operation (esp. runaway downhill situations!) (never though of that either!) [*]Wheel slip [*]Additional prototypical factors [/list] I guess my main takaway is that I can now "safely" switch to 2.5% max in the design, which will indeed solve the particular problems I was running into. 

So thanks again!! 

Cliff

PS, unless it's already been done, this subject seems (to me at least) a good candidate for a GR article!










Cliff
Welcome back to earth...lol

10 cars would be a long train on the old V & T for a single engine, doubling a hill was common too.

Other than Lumber and Machinery, it was loads down and empties up, our cars weigh the same either way...

Regarding your publishing plans; Not only do we want mention, we want our share of the prize! lol Should this egg ever hatch.. lol

John


----------



## CliffyJ (Apr 29, 2009)

Good on you John for knowing your RR history. Yep, the V&T hauled short 'uns, at least back and forth from Virginia City. 

Hey, it wouldn't be ME doing the writing -- !!

BTW, just so you know, I DID git off my duff: we got 2 huge tree stumps out yesterday -- and my back's gonna be paying for it all week! Today I needed to rest up and get back down on my duff, so I did some more design work...


----------

