TSU meaning in Regional ?

Tulsa-Sapulpa Union Railway Company, L.L.C. (reporting mark TSU) is a Class III shortline rail carrier which operates freight service between Tulsa, Oklahoma and Sapulpa, Oklahoma over 10 miles of track known as the Sapulpa Lead, as well as leases and operates a 12.9 mile section of Union Pacific track known as the Jenks Industrial Lead between Tulsa and Jenks, Oklahoma. The line connects with two Class I railroads, being the Union Pacific at Tulsa and the BNSF at Sapulpa, and additionally connects to its fellow Class III shortline, the Sand Springs Railway, in Tulsa. It is owned by the Collins Family Trust. Major customers on the Sapulpa Lead include Technotherm, Prescor, and Ardagh Glass, and on the Jenks Industrial Lead, the Sinclair Oil Refinery, Kentube, Word Industries, Pepsi Cola, and Kimberly-Clark.