The old main and one in the hole were entrance or exit tracks into the Cedar Hill complex from Airline Jct.
They had overhead wires. The subway tracks tied into the Old Main deep into the yard.
The link enclosed will show the Subway track that is to the extreme right, then the Old Main, One in the hole and two in the hole to the coal ramp had no wires. They were the ready tracks for the steamers and diesels that came after.
The picture shows a string of engines coming off track one to go into the engine house service tracks under the coal tower.
Airline Jct was located just about where the second engine in the string is located, on the west bank of course. Bob L.