In　this　paper,　a　revised　four-stage　traffic　plan　method　is　proposed　to　estimate　the　post-earthquake　traffic　flow　assigned　to　a　road　network.　We　also　suggest　a　post-earthquake　road　capacity　estimation　method　that　considers　the　seismic　vulnerability　of　structures　and　the　potential　building　collapse　area　that　might　occupy　a　road　after　a　major　earthquake.　Through　an　analysis　of　the　＇randomicity＇　of　traffic　demands　(traffic　flow)　and　road　capacities　after　an　earthquake,　and　depending　on　reliability　theory,　the　＇unblocked＇　reliability　of　road　segments　and　the　reliability　of　the　entire　transportation　network　can　be　estimated　using　techniques　presented　in　this　paper.　Through　the　component　importance　analysis,　the　optimum　improvement　and　thus,　optimum　recovery　plan　for　a　transportation　system　that　focuses　on　alleviating　earthquake　indirect　losses　is　suggested.　At　the　end　of　this　paper,　an　example　is　given　to　illustrate　the　application　of　the　unblocked　reliability　index　in　post-earthquake　traffic　condition　estimation　and　in　developing　earthquake　response　strategies　for　urban　transportation　systems.