Just about ready to start laying track which consist of 096, 084 and 072 track.
What is the proper distant away from the wall? Also the correct spacing between the 3 different curves. My longest cars are 18" long coaches. I do not have any large steam engines such as a big boy or cab forward.
Thank you for your help.
Replies sorted oldest to newest
I'm not sure what the rule of thumb is on large radii like you're using but you should still test spacing with the engines and rolling stock with the biggest iverhang on both outside and inside of curves.
Here's the NMRA Track Spacing Page, the O-scale is the first set of tables.
To get your curves to be concentric, the track spacing would be six inches.
David Johnson is correct. Six inch spacing center to center will give you concentric curves. It also provides clearance between all known three rail locomotives and rolling stock.
If you are working in three rail I would ignore NMRA Standard 8 along with most other NMRA standards for track work. They are either hopelessly out or date or simply not relevant to 3 rail equipment.
If you read Standard 8 and look in the table for 36 to 48 inchradius track (that means O-72 to O-96 diameter curves) you will see that large steam locomotives or scale length passenger cars are not recommended.
I'm very glad the Atlas, Lionel, MTH, Sunset/3rd Rail/Golden Gate Depot and Weaver have disregarded the NMRAs recommendation. We should too. 
I am not saying that all NMRA's standards are for H.O. and N scale but a lot of it is for those two. Most of the NMRA standards were designed by H.O. people.
The best rule to follow is to check for overhang with your largest locomotives at a very slow speed around the track and see if something hits or not. Six inch spacing is probally the best, sometimes more with a large steam engine like an articulated model. Don't forget the top cab overhang factor, or the tender's steps on an MTH steamer, when doing track side scenery.
Lee Fritz
Access to this requires an OGR Forum Supporting Membership
