Elevator won't move
Man, I don't know the complete scene you are creating, so it's difficult to be of more help 
If you actually need it to go backwards, just use the output StartBackwards although remember that you need to set a non-zero value for the property "New train speed" into EACH of the path_tracks involved in the train's movement for this output to work. I've used many times this output and works out great 
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That would be a good idea but I need the train to be going normal speed until it stops, then when it starts coming down go faster, so if I used the new train speed it will make it fast both times...
Also I was editing my post while you were creating one 
, I attached the updated file in my previous post so you can play it and see the sort of thing I'm trying to do.
Hmmm... about this I know why it didn't work. You set this change of speed into the path track no. 10... but if you remember, when I edit your system after the first problem (elevator didn't move at all) I set as "Next Stop target" in the bottom path_track the topmost one called number 11, therefore your train didn't pass through path no. 10
Try setting as "Next Stop Target" the following path to your bottom one (I think the bottom was no. 0, so set as next the no. 1). This way I think your train will pass through all of them to the top; if you set the "AddOuput" output into the last-top path_track after the train has stopped, then when you give it the order to go backwards, it should do it to the new speed, 550. Try it...
useful tools and stuff here on TWP [spoiler]
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One trick with what you're doing: an object in free-fall has roughly constant acceleration, but the best you can do with a func_tracktrain is roughly constant velocity. Try using a phys_convert on the elevator model (or whatever brush the player is colliding with, it'll work on any entity) at the top and watch it fall with perfect physics. 
Hmmm... about this I know why it didn't work. You set this change of speed into the path track no. 10... but if you remember, when I edit your system after the first problem (elevator didn't move at all) I set as "Next Stop target" in the bottom path_track the topmost one called number 11, therefore your train didn't pass through path no. 10
Try setting as "Next Stop Target" the following path to your bottom one (I think the bottom was no. 0, so set as next the no. 1). This way I think your train will pass through all of them to the top; if you set the "AddOuput" output into the last-top path_track after the train has stopped, then when you give it the order to go backwards, it should do it to the new speed, 550. Try it...
Thank you! I never checked my path_tracks. I'll try this later today.
@FelixGriffin: I would do that, but I'm not exactly trying to give it the effect that it's falling, more so that something went wrong with the elevator and now it's traveling at a dangerously high speed. But thank you still!
That output I told you to use (AddOuput > speed 550) was for changing the max speed keyvalue of your func_tracktrain... I insist in what I told you in steam: get rid of the scripts and control the whole system yourself
If that left bug is that the player can almost get out of the elevator when it is falling or going backwards, why don't you parent a disabled func_brush textured with playerclip to it, and you enable it when the elevator starts backwards? There's already one at the bottom part of the elevator shaft shaped like the elevator.
useful tools and stuff here on TWP [spoiler]
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With regard to the clipping problem, I think all you need to do is to parent the "elevator_doorclose_playerclip" entity to the "elevator_1" func_tracktrain. (The names are from "departure_elevator_a4_logic.vmf" but they are probably the same everywhere.) That way, the barrier moves with the player so they can't get stuck in it. Remember to disable it again when you want the player to get out.
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