In　road　traffic,　stalled　vehicles,　spilled　loads　and　traffic　accidents　often　result　in　traffic　jams　or　secondary　accidents.　It　is　better　for　us　to　detect　and　locate　these　non-recurrent　traffic　incidents　accurately　as　soon　as　possible,　so　that　early　warning,　timely　incident　handling　and　speedy　congestion　evacuation　will　be　better　achieved.　This　paper　proposes　an　automatic　detecting　and　locating　method　of　traffic　incidents　in　a　road　segment　based　on　lane-changing　characteristics.　At　regular　time　intervals,　for　each　traffic　lane,　the　method　calculates　the　lane-changing-out　ratio　of　vehicles　and　judges　whether　a　traffic　incident　has　happened.　For　a　traffic-incident　lane,　entry　points　and　exit　points　of　lane-changing　vehicles　are　considered　as　positive　and　negative　samples,　respectively,　then　the　traffic　incident　is　confirmed　further　and　its　position　is　calculated　by　searching　for　the　optimal　separating　surface　of　the　two　kinds　of　samples.　Experimental　results　prove　that　the　method　is　practicable　and　effective.