The 45 will take over the southern third of the 23’s old route, operating between Broad Street and Oregon Avenue in South Philly and 12th and Noble streets in Callowhill (or the Eraserhood, as it’s also known). The 23 will continue to operate from the Germantown Avenue and Bethlehem Pike loop in Chestnut Hill down Germantown Avenue, then 11th and 12th streets, to Chestnut Street in Center City. Northbound Route 23 buses will lay over at the main northbound transfer point between the two lines on 11th Street between Market and Filbert.
Source: Route 23 Split Goes Into Effect Sunday | News | Philadelphia Magazine