I have recently been laying a section of double-track mainline with a track separation of 2" center-to-center. I chose this separation distance mainly because this is the separation of the parallel straight tracks of the Walthers/Shinohara double-crossover turnouts which I plan to use. It’s also consistent with the track separation suggested in the “101 Track Plans” by Linn Westcott. However, I’ve just started building a Double-Track Thru Girder Bridge from Micro Engineering which seems to require a track separation of 2 3/8". Interestingly, the Walthers Double-Track Truss Bridge has a separation of 2 3/16". Are there any doubl-track bridges that use a 2" separation, or do I just lay the bridge track “off-center”?
2 inches track center-to-track center will not be sufficient for curves in HO unless the curves are broader than most folks have room for, so hopefully you are going wider there. The plans in 101 Track Plans were drawn at least 55 years ago when real-life freight equipment and engines were shorter (and many models sacrificed prototype appearance to go around tight curves with less sideswiping). Note that many of those plans cannot be built as drawn, unfortunately, sometimes because of tracks drawn too close together.
A better starting point might be the NMRA’s S-8 track-to-track spacing standard, which takes into account different types of equipment and different minimum radius curves.
My double main line is 2" on center, and I have two Walthers/Shinohara double crossovers which, as you say, are also set up 2" on center.
I have a pair of Walthers Double-Track Truss Bridge sections, back to back, and, again, as you point out, the track separation is 2 3/16" on the bridge. So, what I did was to gradually increase the spacing of the tracks to 2 3/16" as the tracks approached and departed the bridge.
One thing that made my track plan easier to work is that the double mainline curves at an angle before it approaches the bridge from either side, sort of an overasll S-curve, so the gradual increase in separation from 2" to 2 3/16" is not very noticeable, if at all.
Whether there are any double track bridges out there in HO scale, I cannot say. Considering the fact that both Micro Engineering and Walthers makes double track bridges with 2 3/16" separation on center suggests that the spacing may be prototypical on bridges, perhaps for safety reasons. Dunno.
I agree with you. My double mainline track separation is 2" on center, but the curves are 2 1/4" to 2 1/2" on center. A 2" separation on curves would simply not work.
Thanks, You guys are on the ball! The NMRA S-8 standard is 1 13/16" separation for what I assume is straight track. So, I would be OK for the bridges which are on straight track. However, for curved track with 32" radius, a separation of 2 1/8" is suggested for my situation. So, I will have to do a little rework.
I have a lot of passenger cars and knew I would need space between my double mainline so I used 2 1/2". I made a simple template from .030" styrene with two notches filed to fit over both rails on one track and one notch to fit over the closest rail of the second track. Now I just lay one track and use it to make the other ‘follow along’ using the template. Works great and I don’t have to keep checking the distances.