Figuring grades

I use this easy formula for remember it, 1% is 1 inch up or down for 100 inches long , and 8 feet is 96 inches, so roughly 

 

1%  = 1 inch down or up every 8 feet. 

2%  = 2 inches  up or down every 8 feet, or 1 inch for 4 feet. 

 

Percentage. 1 inch rise In 100 inches is 1 percent. 2 feet in 100 feet would be 2 percent. So if your grade starts at 0 and you end up at 5 inches and it runs 200 inches you have a 2.5 percent grade.

that's a good explaination and easy to apply

What percentage is a realistic grade to use?

The smallest you can   Railroads did not like grades, more motive power fuel...

 

1/2 to 1.5 is common. Unfortunately I have a 4.5% on my layout that forces operators to use helpers which make for some fun running and slow moving. http://www.youtube.com/watch?v...zI&feature=g-upl

 

Luckily there was a prototype for that, Saluda Grade on the Norfolk Southern Railway was 4.7%. They stopped using it in 2001.

The B&O had grades around 2.2 percent on the West End between Cumberland and Grafton. After that was built in the 1840s and 50s, Congress passed a law stating the maximum mainline grades couldn't exceed 2%. That was the standard that the roads had to use in the west.

• Get a 2-foot long bubble level.
• Place the level on the right-of-way where you are calculating the grade.
• Raise the lower end of the level until the bubble shows level.
• For each 1/4" that the lower end of the level is off the roadbed, that's 1%.
• For example, if the lower end is 3/4" off the roadbed to make the bubble show level, that is a 3% grade.

3% to 4% is the maximum grade you should consider. If you can keep them to 2.5% or less, all the better. A 4% grade is a serious operating obstacle.

Figuring grades?  I always thought 90% was an "A"...  80% Was a "B"...   

4.5 percent is "fun" ;-)

On a small layout it is tough to get grades under 3%. 

Including the curve grade allowed about 14 ft for a rise of 6" , maybe 3.8%  The bridge is also part of the grade.

 

Down.

 

 

The replacement deck bridge.

Notice that I usually run consist of (2) or more engines on these grades.   

Fellas---thanks!

We are going to shoot for a max of 2.5, but will try to keep it 2 or better.

 

 

There are a few tricks to fudge grades. 

 

One of the simplest is to split the difference.  Instead of going up 6" run one ROW down 3" and one ROW up 3". 

 

A basic example:  If your are building a flat deck layout consider raising the major flat portions such as yard or town or passenger station 3" off the benchwork grid. 

 

From that point then run one line down to the benchwork frame work and the rising grade up 3" from the datum of the flat foot print for the over/under point of passage.

 

When I design a layout I start with all the over/under points and then work all other features around those points for the minimum % rate of grade.

 

This approach will also bring the possibility of more topography opportunities to your layout.

 

I use several 4' Craftsman levels part #39255,  it has one of the vials marked in aprox 1%, 2%, 3% & 4% graduations.  Exactly, the markings read 1/8" increments per foot.

 

I prefer a max of 1.25% grade.

 

HD 5 gallon paint sticks are exactly 1/4" thick.

I always thought the formula was rise over run or rise divided by run (rise/run). A rise of 8" divided by a run of 120" equals .067. Change to a percentage is 6.7% grade.

 

A rise of 8" divided by 240" equals .033. Change to percentage is 3.3% grade.

 

A rise of 8" divided by 360" equals .022. Change to percentage is 2.2% grade.

That's kind of what I implied

And I always thought a grade was something you got on your test paper in school

 

I use one of these, it works very well!

I spend more time "grading figures" 

Must be a math or accounting teacher...

14 ft x 12" per foot 168" including curve.  6" x 1/168" = .035   3.5%  Small room.

Either grade is about the same.




More power.

Maintaining speed down is more difficult than up.   Most units/locomotives that I have  with speed control do O.K. on these grades. IMO. The Atlas SW9's don't have speed control but IMO they work quite well as long as there are at least (2).  

Mike

Mike,

Thanks---

 

What brand are the girder bridge sections please?!

 

Brad: 

 

Something that is at least as important as your grade is the transition from level track to the track on the grade.  Don't instantly go from a track with 0% grade to, say, a 3% grade.  You will get too sharp of a vertical curve where the rail transitions from level to grade.  This might cause problems with some low hanging locomotive pilots to hit the rails and short, couplers come uncoulped or other problems.  Do an internet search on vertical curves and grades and you should find some information.  There are formulas on how much distance you should take to gradually bring your track from level to the grade you desire.  You will always have a vertical curve when transitioning from two different grades, it's the severity of the curve that matters. 

 

As an example, if you need to raise a track 5" to cross another track and then return to level and want to use a 2.5% grade it will take more than 200" to get the 5" rise.  You will have to add some distance at the bottom of the grade to transition to the grade, and more distance at the top to transition back to level. 

 

This is similar to using easement curves, but in the vertical sense rather than horizontal.  

I use 36" for vertical curve transitions.  Net vertical yield on each transition is aprox 1/8"-1/4" depending on grade.

Mike, how was the timliness of product delivery from Bridge Solutions?

 

How would you compare quality, design and cost between the two? tt

 

A 3% grade is 3" rise in 100" of run

 

At a 3 % grade to achieve 6" of rise     3"/100" = 6"

 

total run required is 6 X 100/3= 200" 

 

OR- at 2% grade to elevate to 5"- the minimum height to cross over another track in O gauge:

 

2"/100" = 5"

 

total run required is 5 X 100/2 = 250"          (20' 10"!)

 

 

To find the run you need- plug in the 2 variables and multiply the rise by 100 and divide the rise by grade

 

The easement is a good idea, especially if your grade starts right at a curve and the pitch is over 3 %.  Your trains will tackle a 3.5% grade without a problem if you are tight on space.  Best to stay under that if possible.  I have done a 3.5% up to 5" which needs 144" of run.  That works, but is not a best case scenario