Maintenance for USH is on the first floor. I see no evidence to suggest otherwise here.
There's a lot more wiring on the track than you think. The bus bars that span the length of the track are physically isolated to create block zones (kind of like a roller coaster). There are 6 bus bars that span the length of each zone: 3-phase, ground, a "go" signal that enables the vehicle to move, and another that does something else (my hunch is a control for RV resets. Here it may be used as a "reverse enable" of sorts so that the vehicles always know if they're on the second floor or the first. The RV's base is actually moving in reverse on the second floor.) Each zone has it's own PLC.
The system is NOT controlling each vehicle individually. When a vehicle enters a zone, it shunts the 3-phase and the ground in that zone, telling the previous zone PLC to turn off its bus bar that is producing its "go" signal. So if a vehicle catches up to another one, it will run into a zone without the enable and stop.
All that being said, we now have at least 6 wires going to the track in each zone. The zones range from 5 feet long to 15 feet (well, they do in Spider-man at least.) Then add all the proxy switches that are on the track every 3 feet or so. Then in the station there's proxy switches on the track every 6 inches or so. <---All these likely have to be wired to their respective zone PLC. Then you have your track switches to deal with.
There's a LOT of wiring under there.