The Collaborative International Dictionary of English v.0.48:

Train dispatcher \Train dispatcher\
   An official who gives the orders on a railroad as to the
   running of trains and their right of way.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

train dispatcher
    n 1: a railroad employer who is in charge of a railway yard
         [syn: yardmaster, trainmaster, train dispatcher]