The following words and terms, when used in this Subchapter, shall have the following meaning, unless the context clearly indicates otherwise:
" AREA AREMA Manual" means , the American Railway Engineering and Maintenance-of-Way Association 's Manual.
"MUTCD" means, the Manual on Uniform Traffic Control Devices, which is the Federal Highway Administration ("FHWA") standard for signs, signals and pavement markings in the U.S.
"Track clearance" means , the shortest horizontal distance between the center lines of adjacent tracks.
Okla. Admin. Code § 165:32-5-1