Jim Shull (former WDI) is the one who said it on an episode of the Disney Dish Podcast. From the Feb 19, 2024 episode show notes:
Jim Shull says:
Well, let’s think about the purpose of the Utilidor system in the Magic Kingdom. It’s to service restaurants and retail mostly, as well as serving to give the Cast Members a discreet way to enter and exit the guest areas. The Cast Member playing Alice doesn’t disappear down a rabbit hole, she simply walks through a door, steps down a staircase and works to avoid the service vehicles in the Utilidor tunnels.
Also, we need to keep in mind that the Utilidor system isn’t really a tunnel system. It’s really the first floor of the Magic Kingdom. The decision to build Disney’s first park in Florida resulted in the decision to build a level for service and then build the second level above for the rides, shows and attractions. I’ve walked around in the Utilidors and what’s notable is that the system is level and that means the Speedway which is lower than the guest pathway is actually nearly level with the Utilidor tunnel right next to it.
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