There are two pairs of escalators in this station.
Between the Main Concourse and the Low Level Concourse. The top of these escalators is to your right (west) of the gate line leading east onto platforms 11 - 15. Note that the steps are to your right (west) of the upward escalator. You go down south.
Between the Low Level Concourse and Intermediate Level The top of these escalators is at the far left (east) side as you come into the concourse from the high level part of the station. These escalators are in front of you as you come in from the north side of Argyle Street. You go down west.
The left-hand escalator is normally the one you need.
Glasgow Central Station
© 2013, Terry Robinson