I didn't quite understand.
1) At the beginning of that level you find some bazooka ammunition and a med kit, then climb down the ladder.
2) Now as you walk to the other side of the room the hoverbots approach. You shoot them with the bazooka.
3) Now you continue until you are opposite to the ladder, stepping up the stairs.
4) There is an elevator platform. Step on it to activate the elevator.
5) When you are up on the balcony, jump back down. Under the elevator in the slot there is a button which opens the slope which leads subway.
This is as far as I remember, but I don't remeber any ledge which needs to be jumped at that place.