Based　on　field　data　collected　in　Beijing　city,　this　paper　analyzes　the　running　speed　and　its　influencing　factors　on　urban　major　streets.　The　base　running　speed　is　defined　under　suggested　base　conditions　and　calibrated　based　on　the　BPR　impedance　function.　In　order　to　derive　actual　running　speed,　the　influencing　factors　of　running　speed　are　analyzed,　including　segment　length,　and　number　of　lanes,　bus　stops,　pedestrian　crossings,　and　access　points.　According　to　the　relationships　between　running　speed　and　its　influencing　factors,　the　adjustment　factors　for　base　running　speed　are　identified.　By　modifying　base　running　speed　through　these　adjustment　factors,　actual　running　speed　can　be　obtained.　©　2010　ASCE.