74 Pa. C.S. § 9201
The following words and phrases when used in this chapter shall have the meanings given to them in this section unless the context clearly indicates otherwise:
"Critical corridor." Either of the following:
"Department." The Department of Transportation of the Commonwealth.
"Designated traffic corridor." A State or municipal highway segment, other than a critical corridor, determined by the Secretary of Transportation to be subject to the provisions of this chapter.
"Existing agreement." An agreement between the department and a municipality for the maintenance of a traffic signal existing prior to the effective date of this section.
"Maintenance." The activity of keeping a traffic signal in proper working condition during the useful life of the traffic signal.
"Municipality." A county, city, borough, incorporated town , township or home rule municipality.
"Replace." The modernization of an existing traffic signal within a critical or designated traffic corridor.
"Synchronize." The coordination of the timing of all traffic signals within a critical or designated traffic corridor for the purpose of operating as a single system.
"Timing." The programming of traffic signals within a critical or designated traffic corridor in order to synchronize the signals.
74 Pa.C.S. § 9201