How is grade % measured?

[Anonymous]

I figure there's a simple formula to it, like 'x' number of feet of rise over every 100 feet of run, thus if the track rose 3 feet over the course of a 100 foot section of track, it would be a 3% grade, is that right? What is the correct way to measure grade percentage? Also, in modern railroading terms, what would be considered 'steep' for mainline Class 1 railroads?

[Anonymous]

You are correct. 3 feet of rise in 100 feet is a 3% grade. On a mainline railroad 1 - 1.5% would be a steep grade. Anything above 1.5% would be a very steep grade. The thing to remember that the railroad is most concerned about the "Ruling Grade" the grade which determines the maximum tonnage which can be hauled over a particular line. A line can average .5% but if any part of the line is 1% the Ruling Grade is 1%.

[Anonymous]

So even though 1.5% is considered steep for the prototype, 3% wouldn't be out of the question on an HO layout, right?

[Anonymous]

3% should be OK unless you are running trains longer than 15 cars with one loco. Since the tractive effort of locos can vary widely you have to be prepared to see what actually happens.

[DSchmitt]

QUOTE: Originally posted by jshrade

So even though 1.5% is considered steep for the prototype, 3% wouldn't be out of the question on an HO layout, right?

Depends:

As with the prototype steeper grades mean less tonnage (poundage? or ounceage? on a model railroad) can be hauled by the locomotives.

But trains on model railroads are usually much shorter than the prototype. and the lengths of our grades are shorter.

Can your locos haul your trains up the grade?

It is often (atthough less than in the past) recommended to make model grades steeper than prototype to make them more prominent both scenically and operationally.

Also depends on what type of railroad and where it fits in the real world.

[Anonymous]

Well my railroad will be CSX located in the Georgia foothills of the Appalachian mountains, so nothing too terribly steep, but enough grades to give some variance to the scenery and demonstrate that it is located in hilly terrain. I doubt I'll need anything as steep as 3% anyway, just didn't know what would look 'right' on a layout and what would definitely be out of place.

[dehusman]

The way I keep a consistent grade on my layout is to take some 1/8 thick by 1 or 1 1/2 in wide balsa wood and cut a series of pieces that start at 3 in long and decrease by 1/2 in on each piece. I then glue them in a stack , with one end of each piece lining up to form a "staircase" looking piece. I then put a 2 foot level on the grade and put the balsa block under the low end. Each step is about 1/2 % of grade. So if I put the end of the level on the 3rd step, that's 1.5% grade. I then adjust my risers under the roadbed until the level indicates level (with the low end on the 3rd step) and shaazam, a 1.5% grade. Move the level up a foot or two and do it all over again. A quick and dirty method of getting a consistent grade of a known steepness.

Dave H.

[Sperandeo]

Hello 'jshrade,"

Dave Husman's grade measuring technique works very well, but you might find it easier to do with an adjustable attachment on the end of a level. See the K-Tool Grade Gauge on page 922 of the 2005 Walthers HO catalog, or go to www.walthers.com and search for item no. 211-150. It's easy-to-use and accurate, and works with almost any 2-foot or 4-foot level.

If you know the amount of rise you want to reach and the length of travel you can allow to reach it, you can divide the rise by the travel and the answer will be the percent of the grade. For example, 4 inches divided by 120 inches (12 feet) = .033, or a 3.3 percent grade.

Good luck,

Andy

[Sperandeo]

OOPS! Everything I said before about figuring the percent of grade was correct, except when I indicated that 120 inches equalled 12 feet. Of course 120 inches equals 10 feet. - Andy

[Anonymous]

Just one recommendation:

I was reading things onWorld'sGreatestHobby.com, and they said that a 2% grade reduces a locomotives pulling power by 1/2. Every 1% increase in grade (after 2%) will cut a locomotive's power in half again . Surprising.

[Anonymous]

Does that apply to model or full scale locos?

[Mark300]

QUOTE: Originally posted by jshrade

I figure there's a simple formula to it, like 'x' number of feet of rise over every 100 feet of run, thus if the track rose 3 feet over the course of a 100 foot section of track, it would be a 3% grade, is that right? What is the correct way to measure grade percentage?

After many decades I can still hear my Algebra 1 teacher when it comes to figuring gradient........

'RISE over RUN.'

To get to percent.....multiply by 100.

QUOTE: Originally posted by jshrade

Also, in modern railroading terms, what would be considered 'steep' for mainline Class 1 railroads?

Over 1.5%......1.75% requires additional assistance with pushers or double heading. The Saluda grade in North Carolina on the former Southern RR (Now NS) was one of the steepest at about 3% (or steeper). & I believe that line is now out of service.

HTH

Mark

[nobullchitbids]

FYI: Prototype grades,

The top of Cahon Pass is four per cent.

Tehachapi Loop I recall is 2.8 per cent.

The ruling grade east from Ogden (where the Big Boys roamed) is 1.14 per cent.

The ruling grade in the Blue Mountains in days of steam was 2.2 per cent.

I vaguely recall that Raton Pass (on the Santa Fe) is about 3.8 per cent.

Prototypes will use grades as high as four per cent if they have to but definitely don't like it, since such require helper service.

O-scalers I have known tell me one trick for modelers to use is to lay rails of steel on heavy grades to maximize tractive effort (nickel-silver is quite slick, will allow only half the "tonnage" of steel). Since steel rusts and does not conduct electricity well, the passages need to be short and accessable to allow for frequent cleaning. Using stainless helps, if you can find rail made from that alloy, although stainless is slicker than cold rolled. If your practice is to tack on a helper for such sharp grades, installing contact shoes on the helper probably will improve electrical pick-up, where steel is used, and give the necessary occasional pu***o locomotives not so encumbered.

[Anonymous]

On the subject of grades I find a maximum of 2.5% is a workable grade for our HO trains. Double headed steam on a passenger train looks great.

One thing not mentioned so far is the effect of curves on a grade. This increases the drag of the train which affects the pulling power of the locomotives. Most grades I have experienced are used to return the rite of way back over itself which meants a continous curve of 30 inches or greater for a climb of at least 4 inches.

I also do not like the look of flat surface layouts. i prefer to allow sags in the road bed just as you see looking down a railroad rite of way. I span a length of road bed between two points and let the natural spring of the material decide the height of the risers between. Remembering to avoid sharp changes in grade so couplers do not come uncoupled and locomotive pilots bottom out. This adds visual interest to the layout and can challenge an engineer to maintain an even performance.

But as always with fitting an unlimited railroad empire in a finite space allowances must be made for reality.[2c]

[Anonymous]

Trains magazine has a nice "trains for dummies" web page with lots of great articles from past magazines on the basics of trains and train operations, including railroad grades. Go to www.trainsmag.com. (You may need to have a (free) Trains web account to go further). About halfway down that page, look for the "New to Railroading?" section and click on the link there called "ABCs of Railroads". It takes you to about 5 pages of interesting topics, including one on page 4 called "Grades and Curves". They talk about "ruling grades" and the steepest railroad grades in the U.S. as mentioned in previous posts. I know about the grades article because I just happen to read it yesterday because I had the same kind of questions.

[steveblackledge]

I model in HO scale and i have a run with a ruling grade of 3.25% on my lower section, just to add to the fun it goes round a 180 degree turn at approx 25" radius. now the fun begins, a P2K SD 60 on level track will pull anything i put on but on the incline the pulling power drops off very fast untill it will only pull about 12 -15 cars before it starts to slip, i have fitted KD metal wheels to improve the rolling resistance over plastic wheels

[oldyardgoat]

A couple of corrections, if I may. Old grade over Cajon Pass was 2.2% ( new grade is about 1.25%. The main reason for the change was the 10-degree curve just west of Summit. Saluda was 5.2%, steepest main line grade in the country. Steepest transcontinental grade is Raton Pass at 3.5% on eastern side, 3.3% on the west side. There is a short piece near the old Wootton Ranch House (razed in 1983) of 3.7%. Sherman Hill's original grade is 1.83%, the (1953) "Harriman" line is 1%. Tehachapi is 2.25%, while the grade to the Moffat Tunnel from Denver is a steady 2.0%. The now embargoed Tennessee Pass line, on the west side from Minturn is 3.0%.
Way back before 1959, Santa Fe had real headache at Ash Fork, Az. Ruling grades of 2.25% went both ways, east to Williams, west to Crookton, near Seligman, both helper grades. Water for Steam engines was too bad to even treat. 300 tank cars of water had to brought in from near Prescott every day. Weather conditions were second only to Donner Pass (2.5%). Not only were the winters nasty, summers were miserably hot. This all explains why this territory - Winslow to Needles - was dieselized in the 1940s, during WWII, and why the Williams cutoff was built (1.0%) in the late 1950s. Also, there was a tunnel in Johnson Canyon that determined the limits of the "Hi-Level" cars of the El Capitan in 1956. Today's Amtrak Superliners would have been "topped", and shredded by the unbelievably thick cast iron lining of Johnson Tunnel. The eastbound grade from the Colo. River to Yampai, west of Seligman, was about 100 miles of 1.42%, longest helper district in the country during the steam era. That was one mean piece of railroad.
Anything over 2.0% is considered a steep grade on the prototype.

[Anonymous]

All of this discussion about grades has inspired my next project. I am going to branch off of my mainline and model the Saluda Grade. Thanks guys!

[nobullchitbids]

Yes, I think when one measures the entire grade at Cajon, it is much less, and of course a railroad would be interested solely in the ruling grade for a particular length of train.

However, I recall reading somewhere that the top of the U.P. line, just as it goes over the hill and for how far I don't know, was 4 per cent. This may be so short that it is not a ruling grade for freights.

I once took the City of Los Angeles eastbound through there and remember that we definitely weren't going very fast at that point! And the 16-car consist had 4 E-9s on the head!