Mixed　traffic　phenomenon　is　one　of　the　most　remarkable　characteristics　in　Chinese　cities,　which　can　cause　traffic　congestion　and　traffic　accident　in　urban　traffic　intersection　in　China.　So　in　order　to　create　the　optimum　control　strategy　of　signalized　intersection,　and　to　simulate　the　intersection　traffic,　this　paper　presents　a　new　method　to　calculate　the　reduced　velocity　of　pedestrians　and　cyclists　conglomeration.　Firstly,　this　paper　presents　the　new　definition　of　the　pedestrians　and　bicycles　conglomeration,　and　from　the　time-displacement　chart　of　the　pedestrians　and　bicycles　conglomeration,　it　describes　the　dynamic　change　of　the　velocity　of　the　conglomeration　qualitatively.　Then,　based　on　the　two　phase　flow　theories,　it　researches　the　speed　of　the　pedestrians　and　bicycles　conglomeration,　and　formulates　the　reduced　speed　model　of　it.　Finally,　the　application　of　this　model　is　illustrated　with　the　signalized　intersection　of　Beijing　Pingleyuan,　using　the　video　method　to　get　the　real　time　velocity　of　the　pedestrians　and　bicycles,　and　based　on　the　reduced　speed　model;　it　analyzes　the　changes　of　the　reduced　speed　of　the　conglomeration.　Copyright　ASCE　2009.