Newbie trestle/grade question

A 4.5% grade should be do-able for short trains. Your best bet is to rig it up temporary and try it out with your own track and trains. Avoid abrupt changes in grade at the top and bottom. If you have the space, I would recommend reducing the grade somewhat on sharp curves as compared to the straight sections. Depending on your trains and transformer, you may find speed control touchy going up and down.

 

I did this small trial layout with grades about 5% (1/2" per track section) and found it tricky to control conventional postwar trains going downgrade. It's a good idea to arrange scenery to cushion a train that might overspeed and fall over.

 

Good to know though it will be a challenge to find more room on my layout to reduce the climb. Below is a pic from SCARM showing what I'm planning (addition in red). In theory I could start the grade just past the switch in the lower left but I really want to keep some of that straight stretch level for operating accessories. Would replacing the bottom right O36 curves with O72 curves make it easier to control the train speed on the descent? The transformer and controls are in the lower right corner so catching a derailing train should be easy though I'd still like to avoid it.

 

Consider splitting the grade.  For example, go down say 2.25% on the lower level and up 2.25% on the upper level.  

I agree with Ace's comments.  If your engines have MagneTraction or traction tires, they should be okay going up, but I got tired of carefully watching the speed of Postwar as they went downhill.  I've eliminated grades on my current layout for that reason, plus not all my locos have the traction aids.

How do you do that on a layout like this with the crossovers and switch locations where they are?

Splitting the grade is possible but would substantially complicate construction of the layout. As it sits, the lower part of the layout is all flat which makes for easier construction, more convenient operation on the main lower level, and more flat space for buildings etc.

 

If it was for me, I would maybe start the grade near the switch at lower left to reduce the grade, and try to find another place for the operating accessories. Or accept the 4.5% grade as an operating challenge on the branch. I think wider curves on the graded track at the right side would be a good idea to reduce the chance of derailment if a train runs away.

I don't think you can without moving them.  That's a whole nuther puzzle.  As usual its all about the tradeoffs.  It depends on what is more important to the original poster.  

 

Another issue with splitting the grade is that you will not have a level loop and will always be encountering a grade on the loops, albeit a smaller one.

 

Here is a RRTrack plan of my layout.  Lots of track in a small 13 by 15 space I know.  3 levels, 3 loops, all connected, 072 minimum.  First pic is all the track.  I split the grade on the right side.  The outer loop goes up from the top of the page to the bottom of the page (this loop is shown separately in the second pic) and the inner loop, or really the right reversing loop goes down from the top of the page to the bottom of the page (this loop is shown in the third pic).

 

I wanted to split it evenly, something like 3.25 inches up and 3.25 inches down, I don't recall exactly, but my carpentering skills are not good and the inner goes down something like 2.5 inches, so the upper had to go up something like 4 inches.

 

So I have no flat complete loops, and the grades make for heavy trains.  But the room is smallish and the modern engines I run handle the grades with 22 car trains if needed (though doing that all the time is probably not great on the motors I'm guessing, so I usually rung around 10 to 15).

 

 

 

 

Why not have an upper loop and a lower loop separate? You can still have your trestles and add to it later . Add a connecting ramp later or add another loop or layer as you gain more experience. Good luck David56

Here is a link to a thread done October 25, 2012, (Figuring grades, on the 2 rail forum), that has a lot of good information on building grades.     2%, 3% and even 4% grades can take a lot of track to get the rise/fall you want.   Click on the underlined phrase to link.