At the end of each siding, as in reality, there needs to be a bumper to keep the train from running off the end of the track. Taking a quick look at a couple of online suppliers I decided to make my own.
My bumpers are not plastic so the bumper shorts the two rails. Obviously insulated unions are needed to connect the bumper assembly to the powered rails.
Some 'rusty' paint to hide the solder would help. The odd bumper is for the head shunt to hold the two blinking LEDs.