This is the arc file of the Traffic Districts layer. It was developed to aid the Traffic Division in planning, organizing, and maintaining traffic flow within the City of Philadelphia. Examples include: the maintenance and placing of stop signs and signals and monitoring street travel direction.
Certain arcs in the arc layer contain data signifying information relating it to the polygon layer. It can tell you if both sides of the arc belong to one of the bounding polygons. All the arcs, including those with no boundary info, have naming attributes for labeling the polygon borders. Contact the Streets GIS unit for public consumption.