Could you kindly point to the county data you're using? I looked at the Metro Transportation Network in King County for Car Mode GIS data. For this road (object id 8781, tlink_id 29654) it just labels it as an Unnamed road, with KC_FCC_ID of L which is a Local Arterial classification. The CFCC_ID is A40, or "Local, neighborhood, rural road, city street, major category". These IDs are also used by the connecting 134th Ave NE.
King County uses code A64 for the CFCC_ID to designate service roads.