Study on unblocked reliability of Beijing, China, urban road network

The urban road network is the basis of urban transportation and its reliability plays an extremely important role in relieving congestion. The present study took unblocked reliability as the index for a road network reliability study. As the saturation cannot fully reflect the traffic situation, first, the formula for unblock reliability was improved and second, the minimal road set algorithm in graph theory was used to simplify the road network as a simple series-parallel network, and by combination with real-time data of the road network in Beijing, China, a calculation method of urban road network reliability was established. Finally, as an extension of the unblocked reliability evaluation, a sensitivity analysis was conducted for each road network and the critical sections in the road network were determined. The simulation results show that the improved unblocked reliability can sensitively reflect the traffic congestion situation and sensitivity analysis based on the unblocked reliability evaluation can effectively locate the sections in the road network that are critical for solving the congestion problem. The results of the study provide reasonable decision-making and theoretic support for traffic management departments.