Abstract: Crushed rock materials had been utilized extensively upon embankments, termed as crushed rock embankment (CRE), along the Qinghai-Tibet Railway in permafrost regions. Based on a long-term monitoring system along the railway, thermal stability and deformation characteristics and mechanisms of CRE were analyzed by field monitoring datasets from 2005 to 2009. The thermal stability analyses indicated that permafrost tables beneath CRE all had upwards movements but to varying degrees. For U-shaped crushed rock embankment (UCRE), the thermal stability of underlying permafrost kept well; along with permafrost table moving upwards, the shallow ground temperatures beneath the embankment decreased obviously while deep ground temperatures kept almost constant. For crushed rock revetment embankment (CCRE), the cooling effect was effective in cold permafrost regions. But in warm permafrost regions, the shallow permafrost beneath the embankment had no obvious cooling trend while the deep permafrost had a slight warming trend. The deformation analyses indicated that CREs experienced frost heave in permafrost regions with mean annual ground temperature (MAGT) < -1.5 °C but settlement in permafrost regions with mean annual ground temperature > -1.5 °C. The magnitudes of both heave and settlement were not significant. Since the better thermal stability of underlying permafrost, it was inferred that the settlement of CRE mainly originated from compression of warm and ice-rich permafrost layer near permafrost table.
Abstract: The foundation pit of Fuqing road station is the first one to be excavated in Ningbo urban rail transit project. To ensure the safety of the foundation pit, a detailed monitoring scheme is established according to the engineering geological condition and design scheme of foundation pit. Due to Ningbo city is located in the classical soft clay area, there may occur pre-warning and dangerous condition during the excavation. Therefore, reinforcement of structure and soil is executed from the aspects of designing, construction, supervision and monitoring. At last, the deformation of foundation pit is controlled and the construction safety is ascertained. Furthermore, the information construction is adopted during the excavation and many data are obtained during the process of monitoring, the displacement of diaphragm wall, ground settlement and axial force of the support are analyzed. In addition, the control measures are presented and can provide reference to the future construction of the other stations.
Abstract: Short-wave irregularity of top rail has great influence on status of both train operation and rail track. Based on the non-contact measurement principle and the virtual instrument development platform with powerful function, the paper designs the system for detecting short-wave irregularity of the top rail based on virtual instrument with the eddy current displacement sensor. The system can realize online real-time display, analysis, processing, storage and search of historical data and printing. With this method, we can detect the smoothness of rails and provide a better scientific basis for making a plan to guide the daily work of track maintenance.
Abstract: The loads and load combination in ballastless track design was briefly introduced. The influence of cracks to the track slab flexural stiffness was studied. According to the mechanical characteristic of ballastless track, the structural coefficient was proposed and put to use in the amendment of different load effect on track slab. The prerequisite of the combination of moment and tensile force was discussed. Take the track slab in bi-block ballastless track for example, the reinforcement in segmental slab and continuous slab was calculated respectively. The results show the reinforcement ratio will substantially reduce when the structural coefficient was considered in the design. In general circumstance, the thermal force in continuous track slab will cause relatively large cracks, in which condition the bending effects cannot be added. The reinforcement in segmental track slab was controlled by train loads, while that in continuous track slab was controlled by thermal force.
Abstract: A new method of widening mountainous highway with T-shaped Integer Cantilevered Road was proposed for steep mountainous areas. Its design principle is casting an integral wall upon the exiting stable roadbed to widen the road without considerable cut and fill. Then the construction technique and work principle were introduced, and the technical, economic and environmental benefits were discussed. Engineering application shows that this method is not only simple, economical, and on the safe side in construction, but also protecting environment further compared with the existing techniques.
Abstract: Achievement of sustainable urban transport requires a means of determining whether progress is being made towards sustainable urban transport. This paper adopts appraisal indicators to provide such a means of assessing progress. The paper first analyses the rapid urbanization phenomenon in china, points out the necessity of sustainability, and discusses sustainable urban transport definition. Three aspects which are impacted by urban transport development are proposed. Then the framework for the evaluation of sustainable urban transport is formulated, and principles needed to be considered when selecting indictors are described. Based on these, specific indicators for the sustainable urban transport are set out, which correspond to the seven questions of the evaluation framework. The various indicators indicate the desired direction of change, and possible disaggregations. Finally, uncertainty of evaluation criteria is studied.
Abstract: Traditional traffic signal timing theory default the number of vehicles through the stop line per unit time as traffic demand. The traditional traffic demand definition obviously cannot respond the real traffic demand when the intersection is oversaturated. The main objective of this paper includes the following contents: (1) to analyze the defects of the traditional traffic demand definition; (2) to strictly define the concept of traffic demand. To achieve the research objective, researchers propose the “traffic demand in cycle” definition: the summation of the standard vehicles queuing during the red light time and the standard vehicles reaching the effective demand region during the non-red light time. The new definition introduces the concept of “effective demand areas”, referring to the areas follow-up vehicles slow down affected by the vehicles that haven’t pass the stop line. The new definition developed in the study can be directly used by traffic engineers and managers to signal timing.
Abstract: This paper provides a contribution to the issue of signal control in a sensitive junction under disaster conditions. A signal control parameters optimization model is presented in order to prevent the spillback of queue in a short approaching link. Starting from an equilibrium equation, store-and-forward method based, this paper depicts the vehicular arrival and departure in a link. In addition, a minimum problem is presented aiming at that the evacuation demand approaching the sensitive junction can depart safely，efficiently with equal opportunities. Then a solution method, based on a improved FW, is proposed. At last, a simulate case via the simulation software – VISSIM is described. The results read that not only the model can prevent the spillback of sensitive phase but also enhance the entire throughout of the junction.
Abstract: The optimum selection of instrument flight procedure design scheme is very important to the enhancement of capacity of terminal area, and to the work quality and efficiency of air traffic management and flight safety. However, in practice, the optimum selection is often made by experts based on their on their specialized knowledge and experience. This human-made selection in most cases could be biased or not optimum. To address this problem, we present an evaluation method based on the relative superiority degree technique. This method makes full use of evaluation information and makes unbiased optimum selection with very low human interference. We give details of using this method in this paper, including constructing evaluation indicator system, obtaining values of each indicator; building evaluation model based on relative superiority degree and finding solution of the model, etc. At the end of this paper, we present a numerical example to demonstrate the feasibility of this method.
Abstract: The researches on competitive mode choice behavior between electric bike and bike are useful for the analysis and forecasting of traffic mode, non-motorized traffic planning and related policy. With the sampling survey data in Kunming, individuals’ attitude and preference are analyzed based on SP data. The competitive choice model between electric bike and bike based on discrete choice model is established. The impact of latent variables on mode choice behavior between bike and electric bike is measured based on the estimation results. The result shows that the latent variables have significant impact on the choice behavior. The latent variables can be used to improve the performance of the model and to better capture taste heterogeneity.