Weaving　section　have　b1een　shown　to　have　an　effect　on　capacity　at　roundabout　approaches,　because　at　weaving　sections　conflict　and　interference　increases,　resulting　in　a　reduction　of　speed.　The　weaving　section　is　the　bottleneck　of　the　traffic　flow.　Therefore,　it　should　be　given　the　highest　priority　in　the　capacity　analysis.　The　current　method　of　calculating　the　approach　capacity　at　a　roundabout　mainly　utilizes　information　about　entry　and　exiting　vehicles.　Few　studies　are　currently　conducted　from　view　of　the　weaving　section　in　capacity　estimation.　The　purpose　of　this　research　is　to　estimate　the　capacity　of　roundabout　by　modeling　weaving　gap　acceptance　at　the　weaving　sections.　For　this　reason,　a　total　of　21　roundabouts　which　are　located　at　the　downtown　and　the　suburb　of　Beijing　are　selected　to　conduct　data　collection.　Significance　analysis　of　speed　at　weaving　sections　has　been　conducted　by　means　of　the　variance　analytic　method.　Regression　models　of　the　entry　vehicles　and　circulating　vehicles　are　built　up.　Based　on　gap　acceptance　theory　a　new　method　is　proposed　to　estimate　the　capacity　of　roundabouts.　Furthermore,　the　relationship　between　the　left　turn　and　through　movements　on　the　capacity　of　roundabouts　is　established.　The　findings　from　this　research　demonstrate　that　capacity　estimates　with　weaving　section　vehicles　result　in　improved　prediction　of　the　actual　capacity　of　a　roundabout.　Furthermore,　the　geometrical　design　of　roundabout　is　another　important　factor　which　influence　the　capacity　of　roundabout,　needs　to　be　further　explored.　(C)　2012　Published　by　Elsevier　B.V.　Selection　and/or　peer　review　under　responsibility　of　Beijing　Jiaotong　University　[BJU],　Systems　Engineering　Society　of　China　(SESC)