Quick Tip
Just a quick tip, if you are having trouble with the underground elevator entrance instance, go in and put another trigger right at the floor of the actual elevator piece that you want to spawn in, and then, on starttouch, make it make the track_train entity startforward. Then spawn yourself with the portal gun in your actual map, above (without touching) the trigger so you just fall a couple units on to it and trigger it.
[spoiler][SP] Alternate[/spoiler]
Or, if you are using the arrival_departure_transition_ents.vmf, simply put a info_teleport_destination instead of the info_player_start and name it "@arrival_teleport".
The game uses the "sp_transition_list.nut" (lines 257-294) to determine where the player should spawn after a transition (between maps). The tube/turbine elevators have info_teleport_destination in the elevator logic instance named either "@elevator_entry_teleport" or "@arrival_teleport". For some reason, the supplied underground entry elevator does not have the required info_teleport_destination.
Looked everywhere for this. This needs to be sticked somewhere or put into the bible for easy reference.
PortalStories.com
"Oh, in case you got covered in that repulsion gel, here's some advice the lab boys gave me: DO NOT get covered in the repulsion gel."
I had trouble with the start elevators for a very long time before i discovered this tip.
[spoiler][SP] Alternate[/spoiler]