A　real　time　traffic　meteorological　visibility　distance　evaluation　algorithm　in　foggy　weather　by　using　dark　channel　prior　and　lane　detection　methodology　is　proposed　in　this　paper.　In　foggy　image,　dark　channel　prior　directly　provides　accurate　transmission　estimation.　A　novel　lane　detection　algorithm　which　is　called　variable　box　search　(VBS)　is　proposed　in　this　paper.　This　novel　algorithm　only　needs　little　running　time　and　could　maintain　real　time　procession.　Background　generating　and　updating　method　which　is　called　Gaussian　mixture　model　(GMM)　will　be　used　to　get　clear　background　image.　Two　endpoints　of　one　traffic　lane　are　marked　and　saved;　these　data　will　be　served　for　traffic　scene　distance　calculation.　Extinction　coefficient　k　could　be　calculated　by　these　two　end　points　transmission　division　based　on　the　monocular　model　and　dark　channel　prior.　Finally,　the　meteorological　visibility　will　be　according　to　definition　from　International　Commission　on　Illumination.　According　to　the　traditional　fog　sorting　methodology,　we　fulfil　fog　category　method　by　our　algorithm　based　on　the　extinction　coefficient　value.　Experimental　data　are　taken　from　the　actual　traffic　scene　and　network　data.　Experimental　results　verify　the　effectiveness　of　this　proposed　algorithm.　Copyright　©　2015　Inderscience　Enterprises　Ltd.