Trains.com

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Subroadbed Width Question

7453 views
5 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    April 2003
  • 305,205 posts
Subroadbed Width Question
Posted by Anonymous on Tuesday, September 23, 2003 9:43 AM
I am planning a much larger railroad and I am going to use open frame L-girder benchwork this time. How wide should the (plywood) subroadbed be on an HO scale railroad to permit attachment of scenery materials? Naturally I will be using two inch track centers so a single track portion would most likely be four inches wide. Also, since I am planning to use a backdrop, how far away from the drywall should I plan for the centerline of the nearest track to the wall? Thanks for your help. - Ed a.k.a. cablebridge
  • Member since
    April 2003
  • 305,205 posts
Subroadbed Width Question
Posted by Anonymous on Tuesday, September 23, 2003 9:43 AM
I am planning a much larger railroad and I am going to use open frame L-girder benchwork this time. How wide should the (plywood) subroadbed be on an HO scale railroad to permit attachment of scenery materials? Naturally I will be using two inch track centers so a single track portion would most likely be four inches wide. Also, since I am planning to use a backdrop, how far away from the drywall should I plan for the centerline of the nearest track to the wall? Thanks for your help. - Ed a.k.a. cablebridge
  • Member since
    April 2003
  • 305,205 posts
Posted by Anonymous on Tuesday, September 23, 2003 11:01 AM
My subroad (plywood) is 3/4" wider than the ties on both sides of the track. This is just enough room for the HO cork roadbed, leaving about 3/16 of exposed ply to attach scenery materials. I achieved this spacing by running a piece of 1x3 and a pencil along the enge of the track that had been temporarily tacked in position.

I don't have a backdrop, since my layout is a 4x8 table, but I would leave at least a few inches so that the shadows of the trains, etc do not fall on the backdrop.

Andrew
  • Member since
    April 2003
  • 305,205 posts
Posted by Anonymous on Tuesday, September 23, 2003 11:01 AM
My subroad (plywood) is 3/4" wider than the ties on both sides of the track. This is just enough room for the HO cork roadbed, leaving about 3/16 of exposed ply to attach scenery materials. I achieved this spacing by running a piece of 1x3 and a pencil along the enge of the track that had been temporarily tacked in position.

I don't have a backdrop, since my layout is a 4x8 table, but I would leave at least a few inches so that the shadows of the trains, etc do not fall on the backdrop.

Andrew
  • Member since
    January 2001
  • From: Guelph, Ont.
  • 1,476 posts
Posted by BR60103 on Tuesday, September 23, 2003 8:35 PM
Unless your scenery has a sudden drop off, leave enough roadbed there for stapling or tacking the scenery base. You might need to put in enough for ditches and fences, or those might be bart of the scenery add-on.
You track probably should be at least 2" from the wall, even more if you run articulateds and other large locos. You don't want the cowcatcher digging into the backdrop.

--David

  • Member since
    January 2001
  • From: Guelph, Ont.
  • 1,476 posts
Posted by BR60103 on Tuesday, September 23, 2003 8:35 PM
Unless your scenery has a sudden drop off, leave enough roadbed there for stapling or tacking the scenery base. You might need to put in enough for ditches and fences, or those might be bart of the scenery add-on.
You track probably should be at least 2" from the wall, even more if you run articulateds and other large locos. You don't want the cowcatcher digging into the backdrop.

--David

  • Member since
    September 2002
  • From: Nova Scotia, Northumberland Shore
  • 2,479 posts
Posted by der5997 on Sunday, September 28, 2003 5:16 PM
Are you going to use rock castings in the scenery near the tracks? If so, add some width to accomodate the extra depth of the castings. Sounds to me that about 4 inches is the answer. This allows for the ditches that make a real scenic difference, but mostly go unmodeled.

"There are always alternatives, Captain" - Spock.

  • Member since
    September 2002
  • From: Nova Scotia, Northumberland Shore
  • 2,479 posts
Posted by der5997 on Sunday, September 28, 2003 5:16 PM
Are you going to use rock castings in the scenery near the tracks? If so, add some width to accomodate the extra depth of the castings. Sounds to me that about 4 inches is the answer. This allows for the ditches that make a real scenic difference, but mostly go unmodeled.

"There are always alternatives, Captain" - Spock.

  • Member since
    November 2002
  • From: US
  • 2,455 posts
Posted by wp8thsub on Sunday, September 28, 2003 11:14 PM
Most people make their subroadbed far too wide. The plywood areas of my HO layout have edges 1 1/4" from the track centers (i.e. single track roadbed is 2 1/2" wide). This width allows for a sufficient ballast slope to the edge of the subraodbed, which represents the width of the compacted fill below the ballast. Ditches drop from there, then scenery either rises or falls from the bottom of the ditch.

If you are modeling a well-maintained right of way, there should be a noticeable stair-step profile from the top of the ballast, down to the fill, then down to the ditch. If you leave the subroadbed wider than the fill, you should use an additional layer below the final roadbed to allow for the ditches. Any dirt or rock cuts should start beyond the ditch. To accompli***his I attach cardboard strips to the bottom of the plywood where a cut will be modeled, then attach the scenery base of more cardboard strips to them. When I'm through plastering, the plaster thickness fills much of the plywood depth and leaves the right size ditch. Anyplace where the track sits atop an embankment, the too wide plywood will really show up and should be cut back.

Railroads that were cheaply built (like most narrow gauge roads and some standard gauge shortlines) usually have less discernable ditches and closer clearances. If in doubt, look for engineering diagrams for a prototype railroad (most had generally similar suggested profiles for rights of way) and measure how wide the top of the compacted fill should be.

One last item to consider is the thickness of your finish scenery materials. make the subroadbed the exact prototype width and it could become too wide one the scenery is completed.

Rob Spangler

  • Member since
    November 2002
  • From: US
  • 2,455 posts
Posted by wp8thsub on Sunday, September 28, 2003 11:14 PM
Most people make their subroadbed far too wide. The plywood areas of my HO layout have edges 1 1/4" from the track centers (i.e. single track roadbed is 2 1/2" wide). This width allows for a sufficient ballast slope to the edge of the subraodbed, which represents the width of the compacted fill below the ballast. Ditches drop from there, then scenery either rises or falls from the bottom of the ditch.

If you are modeling a well-maintained right of way, there should be a noticeable stair-step profile from the top of the ballast, down to the fill, then down to the ditch. If you leave the subroadbed wider than the fill, you should use an additional layer below the final roadbed to allow for the ditches. Any dirt or rock cuts should start beyond the ditch. To accompli***his I attach cardboard strips to the bottom of the plywood where a cut will be modeled, then attach the scenery base of more cardboard strips to them. When I'm through plastering, the plaster thickness fills much of the plywood depth and leaves the right size ditch. Anyplace where the track sits atop an embankment, the too wide plywood will really show up and should be cut back.

Railroads that were cheaply built (like most narrow gauge roads and some standard gauge shortlines) usually have less discernable ditches and closer clearances. If in doubt, look for engineering diagrams for a prototype railroad (most had generally similar suggested profiles for rights of way) and measure how wide the top of the compacted fill should be.

One last item to consider is the thickness of your finish scenery materials. make the subroadbed the exact prototype width and it could become too wide one the scenery is completed.

Rob Spangler

  • Member since
    April 2003
  • 305,205 posts
Posted by Anonymous on Monday, September 29, 2003 7:35 AM
HO double track with 2 inch centers fits well on a 1X4 which is 3.5 inches wide. As to how far from the backdrop, the more the better. Min.would be about 1.5 inches from center with no buildings or tree or anything on straights. Curves need more room as it's a function of car lenght v radius. Buy an 85' car and see if it clears. Allow yourself a little extra or you'll be booting yourself in the duff later. FRED
  • Member since
    April 2003
  • 305,205 posts
Posted by Anonymous on Monday, September 29, 2003 7:35 AM
HO double track with 2 inch centers fits well on a 1X4 which is 3.5 inches wide. As to how far from the backdrop, the more the better. Min.would be about 1.5 inches from center with no buildings or tree or anything on straights. Curves need more room as it's a function of car lenght v radius. Buy an 85' car and see if it clears. Allow yourself a little extra or you'll be booting yourself in the duff later. FRED

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Users Online

There are no community member online

Search the Community

ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
Model Railroader Newsletter See all
Sign up for our FREE e-newsletter and get model railroad news in your inbox!