Applied Mechanics and Materials Vols. 505-506

Abstract: In Urban traffic networks, a road network is usually been divided into several traffic areas by a path or a few paths, which is known as network zoning. In this paper, we present a parameter based on anti-block ability for measuring the zoning effect, which results in the ratio between the average anti-block ability of k sub-networks and the anti-block ability of whole network is minimum. We define the ratio as zoning loss factor of anti-block ability. Minimum the ratio, the model for finding a zoning vital path (ZVP for short) to divide a network into two sub-networks is established, and present an algorithm for computing the ZVP.

Abstract: Traffic state inequality coefficient, an index characterizing traffic state inequality for urban roads, is presented based on traffic state indexes of intersections and links calculated by traffic flow data collected from fixed traffic detectors. And then it establishes the calculation system for traffic state inequality coefficient of intersections, links and networks and determines the ways to classify traffic state inequality. After that, a case study is conducted using Vissim simulation data reproducing the process and results of the identification.

Abstract: With the rapid development of high-speed mobile networks, the mobile applications related to vehicle safety, navigation systems are increasingly present in our lives, it is more and more easy for the driver to understand the situation on the road ahead, and this kind of change will greatly affect future traffic conditions. This article uses cellular automaton to simulate basic road sections, considering two modes of vehicle network safety applications may affect the future traffic flow, through the simulation, analysis the basic traffic flow data, conclude how the future vehicle network safety applications impact on traffic flow.

Abstract: The work on Airlines security risk assessment at home and abroad is mainly confined to safety evaluation, and the research on security risk assessment is very few. Taking an example of flight safety system of an airline, fuzzy comprehensive evaluation and analytic hierarchy process (AHP) is used to calculate the value of the risk of flight safety system based on risk assessment matrix. Flight safety risk assessment index system is established, and weights of the index system are determined by analytic hierarchy process. The indicators relevant values of risk probability and severity are calculated respectively by using fuzzy evaluation. And ultimately the values of flight safety risk assessment are gotten. Example calculations demonstrate the feasibility, effectiveness and practicality.

Abstract: Road traffic is the most widely used for transport security, which have the significant disaster vulnerability. It often becomes the weak link when the evacuation and rescue. MapX is an ActiveX control product with powerful map analysis functions offered by MapInfo Company. Because it does not support the topology of spatial data, the shortest path analysis has become a hot potato for users to develop application systems. In this paper, several key technologies to establish topology structure of road network based on MapX are discussed. On the base, an algorithm for finding the shortest path in post-disaster road network is presented, and experimental results show that the proposed algorithm is more practical and effective. At last, a brief conclusion as well as the expectation for the further study is made.

Abstract: The flow-density model for discontinuous flow on urban street network under under-saturated condition was studied in this paper. According to the concept of two-fluid theory, vehicles in the traffic stream were divided into two classes: stopped (for traffic signal) and moving. The amount of stopped and moving vehicles was estimated by applying fixed number theory and traffic flow theory. Then the model described flow-density relationship was derived on the basis of the concept of space-mean density. After that, impacts of the parameters in the model on the flow-density relationship are analyzed. Finally, twelve simulated conditions were designed and five critical flow was chosen to test the estimated accuracy of the model. Results show that the maximum and average absolute value of relative deviations between exact density and the estimated one was 10.07% and 6.39% respectively.

Abstract: With the rapid development of the civil aviation industry in the world, airline networks become increasingly complex and large, which provide more choices for passengers. To search in airline networks for better connecting paths, it is very time-consuming by existing general K Constrained Shortest Paths (KCSP) algorithms. According to that the acceptable transfer times is generally not more than 3, combined with the structure characteristics of the Yen algorithm, a fast algorithm named as KCSP_Yen is proposed for searching connecting paths in airline networks. At the same time, based on the bounded breadth-first search and A* search, two fast KCSP algorithms are proposed. Finally, the three algorithms are test through experiments on the world airline network.

Abstract: The research provides an occupancy-based performance measurement for Beijing urban expressway traffic that would be beneficial for further improvement of traffic control. An analysis of the field traffic data shows that the phenomenon of speed transition happens frequently once occupancy reaches to the critical occupancy (30%). Analyzed with speed transition probability and state stability at different occupancy and speed, four traffic states could be defined as stable high-speed flow, unstable high-speed flow, unstable low-speed flow and stable low-speed flow. The performance of each traffic state is measured by transportation efficiency. The result shows that once occupancy changes from 30% to 31%, transportation efficiency drop 27.8%, representing an extra 1/4 time cost for all vehicles on road. Therefore lane occupancy should be controlled under 30% to avoid a deteriorating traffic conditions.

Abstract: This paper based on the feature of Beijing urban rail transit sectional passenger flow, combined with Elman neural network. After carrying out modeling experiment many times, a reasonable forecast model about the prediction of urban rail transit sectional passenger flow was established. Then the Elman neural network model was used to predict the sectional passenger flow of Beijing Subway Line 1, from Xidan station to Fuxingmen Station. At last the output results was compared with that of BP neural network, the result shows that the Elman neural network is more precise and effective than the BP neural network in the prediction of urban rail transit sectional passenger flow.

Abstract: This paper presents the development and evaluation of an adaptive two-phrase signal control strategy to resolve conflicting Transit Signal Priority (TSP) requests. The strategy was designed to provide adaptive transit signal priority control, using vehicle systems and existing traffic control devices. In this paper, the strategys efficiency was tested using a micro-simulation software VISSIM and build one arterial road contains five intersections and serves more than twenty conflicting bus lines. The VAP module was used to control TSP of conflicting requests. In the simulation, actual data was used. Finally, control efficiency about adaptive signal control strategy is discussed. The results show that the presented strategy can improve the operation efficiency of bus corporations. This signal control strategy reduced the travel delay time by 33 % to 55% of transit, while has little impact on private traffic. The strategy shows promising results. In addition, with minor upgrades, it can be applied to any type of intersection.