Congestion　has　become　a　significant　issue　in　recent　years　and　has　greatly　affected　the　efficiency　of　urban　traffic　operation.　Random　and　disorderly　lane-changing　behavior　greatly　reduces　traffic　capacity　and　safety.　This　paper　is　mainly　concerned　with　the　relationship　of　lane-changing　spacing　intervals　provided　by　off-ramp　facilities　and　traffic　flow　conditions.　Through　field　investigations　in　Beijing,　several　typical　lane-changing　behaviors　at　off-ramp　areas　are　analyzed.　By　using　field　traffic　data　and　actual　road　geometry　parameters,　VISSIM-based　micro-behavior　simulations　at　off-ramp　areas　are　implemented　to　obtain　traffic　flow　conditions　with　different　lane-changing　spacing　intervals　and　other　model　parameters,　such　as　traffic　volume　and　ratio　of　off-ramp　vehicles.　Then,　the　numerical　relationships　between　traffic　flow　state　and　model　parameters　can　be　shown.　The　results　show　that　with　increasing　traffic　volume　and　the　ratio　of　off-ramp　vehicles,　the　lane-changing　spacing　interval　required　by　vehicles　should　be　increased.　For　the　same　ratio　of　off-ramp　vehicles,　if　the　traffic　volume　increases　by　100　pcu/h/lane　(pcu　is　a　unit　to　stand　for　a　standard　passenger　car),　the　corresponding　lane-changing　spacing　interval　should　be　increased　by　a　spacing　of　50-100　m　to　avoid　increasing　congestion.　Based　on　the　results　of　this　paper,　smart　lane　management　can　be　implemented　by　optimizing　lane-changing　spacing　intervals　and　lane-changing　behaviors　to　improve　traffic　capacity.