I use fine parcel string and will post a couple of photos of work in progress, but I am not going to get it finished today, still it is interesting to see just how well it works. I thought I would have today to work on the layout, but my lovely wife had other ideas - well it is Christmas coming along after all.
I have started laying down the track and the string is in place, so even though it is not finished you will be able to see what is involved. I do not know if you have been following my articles in the snooze, but I was once persuaded that using florists wire was a good thing, but found out to my cost that it was not and have since gone back to the method I employed on other layouts long ago - it works and is still the best and can give transition curves as mentioned above.
After I had established the gradients and curves the next thing was to mark where the string was going to go for the super elevation. If I was laying flexi-track it would have been quicker and easier, but this particular curve also had a check rail - remember a locomotive had come off and rolled down the embankment here once before, so this has meant building track in situ, which makes it just a little stickier, but my method was fairly straightforward once started. There is a little super elevation on the NCB line dropping away in the opposite direction, so this too is marked out in string. Placing the string along where the ends of the sleepers are going to go will give a shallower angle of cant than placing the string directly below the rail on the outer side of the curve. It is clear from the photograph that my intention is to put it equal with the outside of the chair as in the WPR mainline in this photograph.
Looking at the NCB line at the bottom of the photograph you can see the string tapering away towards the edge of the ballast and this is how to achieve the drop in the angle of cant - this is now on the straight. Where the string finally comes out from below the sleepers I simply allow the track to find its level and the key to that is the rail itself eventually coming down to the level. The arrow bottom left shows where the track reaches straight.
The Wemyss line has the check rails fitted I found that it was easier to fit them by cutting lengths of 30ft rail one at a time and fitting them into the chairs already attached to a full length of rail.
Trying to work a long length of rail through the chairs when fitted on another long length is very difficult due to friction. I will only cut the rail after everything has been laid and ballasted.
As a general rule I try to avoid transitions taking place above board joints. - only on a straight section would I consider it and it would have to be with both boards set up and being sure of the boards keeping their levels.