The Arterial layer represents all of the streets in the City of Philadelphia street centerline that the Traffic Division of the Streets Department classified as arterials: class 2 and 3. Data Development:The Arterial layer is derived from the Street Centerline. It is updated in accordance with the centerline update every 2 months. Key Attribute Fields:ST_CODE-Unique Street ID code STNAME-Concatenated field consisting of Pre_dir, St_name, St_type, Suf_dir items SEG_ID-Unique Street Segment ID code CLASS-Street class of arc; 1-Expressways; 2-Major Arterial; 3-Minor Arterial; 4-Collector; 5-Local Coordinate System:Lambert Conformal Conic, NAD83, PA South Stateplane coordinates, US Foot.Thematic mapping:STNAME can be used for labels.