The　purpose　of　this　paper　was　to　better　quantify　the　effects　of　bicycle　traffic　on　vehicular　delays　at　signal　intersections　with　pre-right-turn　lanes.　Through　videotaping　several　signalized　intersections　with　pre-right-turn　lanes　in　Kunming　City,　Jilin　City,　and　Changchun　City　of　China,　traffic　flow　data　was　collected　to　analyze　the　interference　between　the　vehicle　flow　and　bicycle　flow.　It　is　found　that　with　the　increase　of　the　bicycle　traffic　volume,　the　bicycle　lanes　become　congested,　and　bicycle　traffic　is　more　likely　to　encroach　into　the　travel　path　of　motor　vehicles,　and　thus　results　in　the　excessive　vehicle　delays.　On　the　basis　of　empirical　data,　a　calculation　model　was　developed　to　quantify　the　relationship　between　the　oversaturated　bicycle　flow　and　the　additional　operating　delay　caused　by　the　bicycles.　The　result　of　the　analysis　can　be　used　to　calculate　the　capacity　of　the　signalized　intersections　with　pre-right-turn　lanes　and　assist　in　developing　guidelines　for　installation　of　pre-right-turn　lanes　at　signalized　intersections.　©　2011　ASCE.