Grades and clearances

Discussion in 'N / Z Scale Model Trains' started by ezdays, Mar 19, 2003.

  1. ezdays

    ezdays Out AZ way

    OK, I have my benchwork done with 2 1/2" of foam on top of a 34" x 80" door. I have my track laid out full size on a sheet of paper. I have not made any commitmets regarding terrain yet, but again, I'm back to asking some basic questions.

    From what I've read, a 2% grade would be ideal, and 3% would be pushing it. The layout is a modified Atlas N17, with less passing track and a few less sidings and so there is a figure eight that I want to use a bridge on. I also plan on having a road go underneath the tracks at one point. Now the questions: What is the minimum clearance from the top of the track to the bottom of the bridge that passes over it? What about a typical road underpass clearance? The grade I wind up with obviously depends on this clearance, plus I want it to look right.:rolleyes:

  2. kettlestack

    kettlestack Member

    The NMRA standards gauge uses a clearance of 1 11/16ths" (22 scale ft) for tunnel clearance in N so that will be ok for bridges too.

    Road underpasses should not be less than 13 scale feet (1").

    By the way, that's a nice size of layout you've chosen.

  3. scoobyloven

    scoobyloven Member


    the easy way to do the track is to get a 2% incline starter incline set from woodlan i used them on my n scale layout it brings it to 2 inch high a little more then needed but it look good
    and you can't see the differnce and it is alot less stress. on the under pass if you have a siding witch you will use big rigs bye it put the rig and trailer under the brige where ever you will put it and add 3-5 scale feet to the total hight it would give you plenty of room i found some things don't fit under 1" high i used 1 1/4 inch on the under passes on my layout the thing is to see it in your eyes and mock it up to see if it looks good and if that is how you want it
  4. ezdays

    ezdays Out AZ way


    Thanks for the info. I think the size is about all I can handle as my first first layout. I didn't want it too small since I didn't think I could do what I wanted with the scenery and terrain. I can post some pictures of my bench if anyone is interested. I had to do something a bit different since I recently had knee surgery and can't crawl underneath to do my wiring.

  5. kettlestack

    kettlestack Member

    Scooby, I agree with your 1 1/4" clearance for road underpasses. I used the dimensions of a RR bridge over the road I drove to work, it was marked 13' and I know for a fact that all British rigs go under it. Mind you some sharp minded scrap dealer drove his truck under it loaded wayyyyyyy up with crushed cars... hehehe he left two crushed cars lying on the road! :rolleyes:

    Don, I have a bridge on my N layout and didn't like the idea of it being high so I placed a "Hi-cube" boxcar on the tracks and added 1/4" to that for clearance. I assumed that a Hi-cube was the tallest car used in the states ... but then, what do I know of American trains? :( :) :D :D .

  6. ezdays

    ezdays Out AZ way


    If you go down most freeways you'll find clearances of 17 or 18" but I didn't think that was to good for a rural underpass. I still haven't bought any scale trucks or cars since I haven't decided on any era for my layout but I should to get an idea of the scale. I guess I could always buy a couple of 50's woodies. They'd be right for a 50's layout and be antiques if I went for the 90's.:D

  7. absnut

    absnut Member

    Just my humble opinion, EZ, but don't be afraid to push that grade to 2.5 or even 3% if you have to do so. I have two 3% grades on my layout without problems. I also model northern New England so they do not look out of place nor unreasonable. A truck hung up on a "back road" underpass makes for an interesting modeling scene!:)

  8. Tyson Rayles

    Tyson Rayles Active Member

    The area I model in real life has ruling grades in excess of 5%, however I thought that was toooooooo steep for a model (except for logging or mining which this is not) so my ruling grades (and I have a lot of em' :eek: ) are Woodland Scenics 4%er's and I've had no problems.
  9. ezdays

    ezdays Out AZ way


    Ok, I've started cutting and shaping foam, a milestone for me!!!!!:D No more talking about it, my new world is starting to take shape:) I kinda bit the bullet and just have a general idea of where it's heading, but I just got too anxious once I finished by bench I couldn't wait.:rolleyes:

    I roughed in my first grade, and it looks like it's just under 3%. I should be able to hold the others to about the same.

    I'll post a few pictures in a day or so in hopes that maybe you can let me know if I'm screwing up big time and never should have quit my day job.:eek: :eek: :eek:

    D:cool: N
  10. rsn48

    rsn48 Member

    I used to follow the party line and say to almost everyone to stick to 2% to 2.5% then realized I hadn't followed my own advise and it worked. Small layouts can have larger grades because you are pulling smaller train lengths, and often the entire train length isn't on grade. BUT PLEASE PAY ATTENTION TO WHAT FOLLOWS!!!

    If you push the boundaries of grades on your layout - YOU MUST HAVE A VERTICAL EASEMENT. Yes I know the capitals are irritating but I learned this lesson the hard way. The grade I had on my old layout was 9% and believe it or not it worked, but it didn't have an easement at the top and that created problems. You need to ease into the beginning of the grade, then ease out of the grade.
  11. ezdays

    ezdays Out AZ way


    Since this is my first layout, speaking from experience means talking about something I did yesterday :) :) but I'm learning. One thing that is apparent is that on any layout for one to have the track circle around under itself you have to have close to a 2" rise somewhere. At 2% that would take 100" and just wouldn't work. That's what I have and I wound up with four grades and am trying to keep them around 3%, but it is difficult. I don't think I need to go up to 9%, but I think I'll try to go bit steeper and see how that works. Easing in and out of a grade makes good sense.

    Now another question: How about grades around curves? I have one grade I put on a straight section but I think my layout would work better if I moved it to a curved section. I am looking to putting passenger and freight depots right where the grade would be. Is there anything I have to watch out for if I do this? I know somewhere here there was a discussion about putting a slight cant on curves. That would seem tricky to have a rise and a cant too.

    I think I'm going to experiment a bit before I finalize anything. Now would be the right time to make any changes since I'm just now cutting foam and making ramps.

  12. 60103

    60103 Pooh Bah

    Don: The conventional wisdom is that a curve increases the drag so you'll pull less up a curved incline (or have to reduce the grade a bit on curves.) I don't have any formulae. It has also been noted that some locos pull better on curves because there's more friction between the flanges and the rails.
    Can you fiddle the grade by having the lower track go down, or is it the same track? A 2" rise at 2% takes up one whole side of a 4'x8' layout. Then it takes the other side to get down again!
  13. ezdays

    ezdays Out AZ way


    Thanks, I did think about making the lower track go down some like you suggested, but I find I only have to rise 3/4" so I that isn't to bad. Like I said, I think I'm just going to experiment a bit. I did get by my LHS and picked up a couple of inclines. They only had 2% and 4% so I got the 4% base on some of the comment made in this thread. From what you're saying, 4% might be a bit to steep but I should be able to shave that down some.


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