In Search of a Straight Frog

In a switch, the curve can end before or after the frog (or V formed by the inner rails). If it ends before, the rails from which the frog is formed are both straight, which reduces manufacture effort, eases track maintenance, and increases the durability. But dragging out the curved part through the frog and beyond allows for smoother curves. Consequently, straight frogs are a popular choice for yards and inexpensive trackwork while curved frogs are preferred for loops regularly passed by trains.

Until today, I believed that RW simply does not render frogs in straight switches. Either the curved ribbon extends past the frog or you don't get one (and no guiderails either). Then, I saw it render straight frogs in crossovers.

After getting rid of the blocks in flangeways, I had some crossover renaissance. But creating regularly shaped trackwork using them proved very tiring.

Then, I dug into the track XML data to see what was so special with these crossovers.

Now, I know two options, both of which are not exactly attractive, but much more than I had this morning.

The task at hand is the construction of a rake of loops, 4.5 apart, connected to the mainline via 1:9 switches with a radius of 190 m. The curve of this switch is 21.0 m long (rounded to 0.1 m). The length of a 1:9 diagonal from one track centre to the next is 40.8 m for 4.5 m track distance.

Innovative usage of the crossover tool

• Lay some 500 m of straight track for the mainline.
• Create a crossover to the right (since the loops will be at the right). Radius 190, length of curve 21.0. To make sure this radius is used, you need a track rule specifying it.
• Unfortunately, the crossover tool only works on parallel (or very near parallel) track. Therefore, we only get one loop of it. The technique to produce it does not scale to a higher number of tracks.
• Therefore, delete the curve at the far end of the crossover. Extend the straight track by some long straight, for working purposes only.
• Move this new straight to the left, by some 20 m, without rotating it. It will help to inspire the crossover tool end then be deleted.
• Now, add 40.8 m straights to the diverging straight (in place of that straight that we just moved to the side). Their number is equal to the number of loop tracks.
• Now, select the crossover tool, place the gizmo exactly at the small red triangle separating two of these 40.8 m sections and create a crossover to the temporary track on the left. Curve radius is 190 again, and length 21.0.
• After you did this for all the tracks, you delete the temporary track (which now is fragmented into 40.8 m pieces, and the curves connecting to them, leaving nothing but a range of nice switches with parallel tracks of equal length.

Fine, now we only need the opposite and then connect the two. Then, you find out that this simply does not work. The parallel tracks we created are never as exact enough. The will be off by a small number of centimetres, but this is enough to keep RW from joining the track. What is worse is that RW refuses to make such minimal S curves to compensate the small deviations.

You may be able to drag up a 1:100 curve (I hardly managed to created "flatter" ones), but the curve with "snap to track" (where the found target turns pink) does not work at this angle. RW always creates straights, which then do not join, exactly because the are a little apart. I also tried splitting and welding the straights of such an extra-sharp X. Sometimes it works, sometimes not.

Of course, there is not problem with using the join tool to simply make the straights ahead jump that centimetre or three, no one will notice. But what about the other end?

For converging switches, the recommendation I follow is to have a diagonal track across the whole rake and insert curves using "snap to track". If you pick a trackrule that has a somewhat smaller minimum radius, with some practice and patience, you will end up with a row of converging switches in the range of 185 to 195 radius, to approximate 190. However, these switches are of the "usual" type, not rendered as such and marked by a big red rectangle.

So you revert to the crossover method for both ends.

A clever variant is to make sure the parallel lines from the second end cross those from the first one, then you only need to find the place where they perfectly overlap and insert a piece of straight track there, after you cut them back. Less nasty than parallel track, 3 cm apart.

Still, all this is just too much pain in my view.

Poking into the XML
The track layout consists of ribbons which again consist of segments. The difference between a correctly rendered switch with straight frog and on that is not is this: The diverging branch of the switch is formed by a single ribbon, having two segments, first an arc (curved part), and then a straight. The crossover tools creates them that way. In contrast, when you create a curve, followed by a straight, the editor creates two separate ribbons with one segment each (at least when you are near other track or a switch).

Apart from fixing the core game, the solution is this:

• You locate the two ribbons in Tracks.xml (easier in RW thanks to showing part of the ribbon ID in the editor), and in the corresponding file in Track Tiles.
• You cut the cCurveStraight bit from the straight ribbon in the Track Tiles file, delete the now empty hull, and insert the cut out bit after the end of the cCurveArc segment in the curved ribbon.
• In Tracks.xml, you remove the definition of the straight ribbon, noting its length before; then the node which connects the straight ribbon with the curved one.
• Then, you look for the remaining mention of the straight ribbon and replace it by the key of the curved ribbon.
• Then, you add the length of the straight to that of the curve (still in Tracks.xml). Also replace the old length by the new one in the rest of the record, namely for the height and track properties (track rule) information.

Sounds like work, because it is. But at least it has some potential for automatising, which gluing nearly joint track together has not.