Macroscopic　traffic　flow　models　play　a　significant　role　in　the　Intelligent　Transportation　Systems　(ITS),　especially　for　the　urban　traffic　control　and　the　dynamic　traffic　assignment.　Two　main　problems　limit　the　application　of　the　existing　traffic　models.　One　is　the　traffic　dynamics　described　by　the　complex　nonlinear　equations　which　are　difficult　to　resolve　in　real　time,　and　the　other　is　that　some　model　parameters　need　to　be　calibrated　in　prior.　This　paper　presents　a　hybrid　macroscopic　and　microscopic　(macro-microscopic)　traffic　flow　model　of　freeway　traffic　by　extending　the　cell　transmission　model　(CTM)　with　the　real　time　speed　dynamics.　Simple　supplying　and　demanding　functions　are　defined　to　represent　the　traffic　propagation　between　the　upstream　and　downstream　cell　boundaries.　A　microscopic　car-following　model　is　integrated　to　specify　the　dynamics　of　the　average　speed　in　each　cell.　Simulation　results　with　specific　traffic　data　set　collected　from　a　4-kilometre　long　urban　freeway　show　the　performance　of　the　model　compared　to　the　well-known　METANET　model.　©　2011　ASCE.