To　quantify　the　vehicle　access　traffic　impact　area　of　large　public　buildings,　assuming　access　right　turn　traffic　conflict　area　as　its　downstream　functional　area,　traffic　impact　characteristics　of　access　downstream　functional　area　size　are　analyzed.　Further,　with　following　right-turn　vehicle　location　in　traffic　conflicts　taken　as　the　right-turn　conflict　distribution　point,　access　right-turn　conflict　distribution　point　real　coordinate　formulas　based　on　the　photogrammetry　method　are　proposed,　in　order　to　measure　the　right-turn　conflict　area.　Then　through　curve　fitting　right-turn　conflict　coordinate　points,　boundary　points　of　right-turn　conflict　area　are　defined,　so　that　the　access　downstream　functional　area　size　model　is　determined.　Finally,　one　large　public　building　vehicle　access　is　taken　as　an　example　for　result　trial　calculation　and　simulation　validation.　Verification　results　show　that,　urban　street　traffic　delay　in　the　access　downstream　functional　area　has　the　large　value,　and　delay　values　have　rapid　increase　and　slow　decrease　changing　states　successively,　which　fits　the　right-turn　conflict　area　shape　and　size　features.　Therefore　access　functional　area　size　model　based　on　the　right-turn　conflict　area　shape　could　define　the　large　public　building　access　impact　area,　which　is　good　for　urban　street　microscopic　traffic　organization　optimization.　©,　2015　All　right　reserved.