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.

Side view of bumper with car coupler for referenceDifferent view of bumper with train coupler for reference

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.

One down, two to go. Some 'rusty' paint to hide the solder would help.