Here’s the end-of-module joiner that needs installing before the position of BR No.388 can be finalized. The rails get soldered to the PC board, the PC board gets epoxied to the wood and the wood glued to the ply roadbed with carpenter’s glue. Five are required before the trestle can drop into place. The rail in this instance is HO code 70 (Micro Engineering I think) that will sit just proud of the wooden ties and provide a nice flat surface to solder to the base of the code 40 running rail. I’ve used this method before, inspired by something similar in an old issue of the P87 journal. Having gone over to milled acrylic for my switch sliders the stacked rail method is still a robust method of maintaining alignment through module joins.
Prior to soldering the running rail, three piece wooden ties are be added and the works filed to height. Once the height is fixed the rail will be scalloped wit a keen file to allow daylight between the ties and running rail. In the past I did them with a moto-tool and abrasive disc but I find the effect much more pleasing when worked by hand. I start with a triangular file and then move to a rectangular one to clean.