On June 21, 2023, PennDOT published Change #1 to the December 2011 edition of Publication 148, Traffic Standards-Signals, TC-8800 Series. The changes to Publication 148 correspond with changes to the traffic signal specification updates made to PennDOT Publication 408/2020, with the purpose of eliminating conflicting direction and content between the two publications. Edits to identified minor errors (spelling, call-outs, etc.) are also incorporated into this update.
A detailed list of changes is included in the Transmittal Letter at the beginning of the document.