The classic problem with a two-level layout is getting trains from the staging level up to the main level. A helix was ruled out early because the desired radius would eat too much room, and a large incline was tried as well but also swallowed too much space and got torn out. The solution this maker landed on is a train elevator that carries rolling stock straight up between the two levels, and the results look convincing.
The moving platform rides on 600mm linear rails and is lifted by two 16-inch actuators. Metal guide rails fastened to the backboard keep the platform steady as it travels. Control runs through an Arduino with an optocoupler and a BTS7960, operated from a DCC-EX command station, with limit switches handling travel at the moment. A switching power supply feeds a control box that holds a toggle switch, knobs and indicator LEDs, and flipping that switch brings the whole mechanism to life. The bench underneath is dimensional softwood lumber, and the build came together improvised rather than from detailed plans.
A couple of details stand out to me. Going with two actuators instead of one seems like a smart call, since a single one apparently could not keep the platform level. The table is 8 feet long and two lanes will run on the platform, so capacity should beat what a helix or incline could offer, in the maker's own view.
It is not finished, though. The left actuator still needs slowing down to match the right, and no fix for that has been found yet. The table also needs finishing before real layout progress starts. The maker has said a future version would use stepper actuators to avoid limit switches and get finer control over leveling, which sounds like a sensible lesson learned.