In order to effectively serve the route guidance and control management of the expressway corridor network in disastrous events，a method to divide the management unit of road networks is put forward． For the management unit with no disastrous events involved，a travel time characteristic function is established by taking into account the influences of the management unit length，the average speed and the real-time traffic density． By combining the queuing and dissipating characteristics of the management units involving disastrous events and by using the flow and density relationship model，the duration time and dissipation time of incidents are determined，and a travel time calculation model of incident management units is constructed based on the wave theory． Then，the proposed model is modified by taking the real-time safety reliability as a road resistance function． Finally，the effectiveness of the constructed model is verified by an example．