Seattle does something I haven’t really seen elsewhere for their light rail. The trains are powered by overhead electrical catenary wires, and the rails in stations and many tunnels are level to the ground.
So some of the tunnels under the city are just level paved which means the Trolley buses can use the same tunnels as the Train! It was surreal to be on the bus with the diesel engine running through city streets, then the bus took a ramp down to the “train tracks”, hooked up to the catenary overhead, diesel engine stops and electric motor purrs to life, then you’re driving in the same tunnel under the city that the Link train does at other times.
Seattle also has a completely separate light rail transport in its Monorail!