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line of track. I have always found that no matter how well I have planned it, it always works out differently once you start putting the track down. One thing you can use if you are not good with computers or drawing software, are the Peco turnout print-offs as a rough guide for what turnouts to buy.
Track and Track Gauge
I discovered I now use code 83 myself, although I have still been using Peco Code 75 for hidden areas and storage sidings. I prefer these over code 100, as I discovered it worked much better with RP25 wheels. I am advised by a Peco representative that both code 75 and 83 are designed to work at optimum efficiency with RP25 wheel-sets. This became most noticeable to me when I first joined the NMRA and built 16’ of modules to the original NMRA standards (except for rail size – the NMRA standard being Code 100 rail while I used code 75). Back then I regularly took these modules to the monthly Claverton (Cyder Belt) NMRA Group meets (my closest modular group), and saw a clear difference in locomotive traction and the resulting lower track noise levels (on ballasted track).
I have already explained the term “Code” in relation to rail size but how does this apply to the prototype? NMRA Recommended Practice RP15.1 is particularly useful in selecting rail size. Firstly it gives the absolute dimensions of a rail of a particular size (rail height, rail head width, railhead height, base width, etc.). It then goes on to show what size prototype rail a particular code rail equates to. For example, Code 83 approximates to 132lb/yard rail in HO or 55lb/yard in O scale.
It goes on to provide a useful table showing the types of rail size (by percentage) used by the prototype at various dates. This helps you select the most realistic rail size for the prototype that you are modelling.
Other relevant standards are:
 Standard S1 (particularly S1.2) which specifies the gauge and tolerance for track.
 Standard S3 (S3.1 and S3.2) which details the tolerances of track gauge where there are guard rails and check rails.
 Standard S7 deals with general clearances between track and the surrounding scenery and bridges.
 Standard S8 specifies clearances between adjacent tracks for both straight track and curved.
In addition to Standards there are a set of Recommended Practices. Relevant RPs are:
 RP10 Trackage General which details relevant standards RPs and other useful information.
 RP11 Curvature and Rolling Stock gives guidance on suitable minimum curvature for various types of rolling stock.
 RP12 Turnouts gives the dimensions of various sizes of turnout
 RP15 Rail – already discussed above.
Whichever rail code you use, you can mix and match, and gradually upgrade if you feel the need to. Peco have made this process even easier by making available a conversion piece for Code 75 to 100. The earlier version was a bit ‘chunky’, but the SL-113 provides an almost invisible transition and it also demonstrates the difference between the two rail sizes rather well. For any other combination you may need to make your own transition joint, although Shinohara make 75-83 and 83-100 versions. The key is to ensure that the top of the rail and the running edge is continuous at the joints, with no steps or large gaps.
Rail Joints
This brings us on to another popular area of uncertainty – rail joints. How much gap should you leave at rail joins? Theory shows that a yard of nickel silver rail will change in length by about 0.5mm if the temperature changes by 30˚ (freezing point to a hot summer’s day). If it is laid at moderate temperature, the maximum change is not likely to exceed 0.25mm. Well I’ve never left any gaps larger than the thickness of a piece of paper and I have never suffered any buckling or shrinkage issues (but see my soldering comments). I do use insulated joiners, and no matter how ugly you think they are, they do absorb most expansion in average room conditions.
Should the joints be soldered? I did try soldering the joints once, and have worked on layouts with soldered rail joints, but I would not recommend it unless the conditions are extreme. As I recently discovered on my modules, I had a length of track soldered both ends ‘pop’ completely out of the retainers due to the sun shining through a window directly onto it! Where at all possible, I feel it is far better to link the rails electrically across the joints with short jumpers, or better still have extra droppers onto the main bus or feeders, rather than have huge gaps at the end of a run of soldered rail. One common problem I have come across with soldered rail is that it can cause the stock rails (the two main outer rails) of a turnout to move relative to the switch rails. The blades may then not close properly into the cut-out and you will either get derailments or electrical contact issues where you are relying on point blade contact for electrical continuity.
While we are on the subject of track joints, I have never understood why folk use the ‘missing tie’ method with HO track. I have always (carefully) sliced off the chairs or spike plates to allow clearance for the fishplates/track joiners (see photo below).
This method is most effective in avoiding one of the most commonly seen mistakes – the 50 pence curve (see lower photo above), or threepenny bit curve for those my age or older (if you think I’ve spelt it wrong, a thrupenny bit is something quite different!). By paring off the tops of the ties at staggered positions