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651.
ABSTRACTConventional travel time reliability assessment has evolved from road segments to the route level. However, a connection between origin and destination usually consists of multiple routes, thereby providing the option to choose. Having alternatives can compensate for the deterioration of a single route; therefore, this study assesses the reliability and quality of the aggregate of the route set of an origin-destination (OD) pair. This paper proposes two aggregation methods for analyzing the reliability of travel times on the OD level: 1) an adapted Logsum method and 2) a route choice model. The first method analyzes reliability from a network perspective and the second method is based on the reliability as perceived by a traveler choosing his route from the available alternatives. A case study using detailed data on actual travel times illustrates both methods and shows the impact of having variable departure times and the impact of information strategies on travel time reliability. 相似文献
652.
针对低重心斜拉桥边跨墩柱的横向抗震问题,以某在建低重心斜拉桥为背景,进行边跨墩柱横向抗震措施研究。该桥主桥为(45+80+285+80+45)m双塔双索面混凝土斜拉桥,边跨墩柱高度仅为11 m。采用SAP2000建立全桥有限元模型,输入地震动,通过抗弯能力需求比R M评估桥梁的抗震性能,提出改变墩柱截面形式与采用防屈曲支撑构件(BRB)等8种抗震措施,并对比分析各措施墩柱关键截面的R M。结果表明:在地震作用下,设置横向固定支座的边跨墩柱墩底截面弯矩较大、R M均小于1,是低重心斜拉桥横向抗震的薄弱环节;8种抗震措施墩柱关键截面的R M均大于1,各措施均可改善边跨墩柱的横向抗震性能,措施Ⅱ-6(将边跨墩柱改为双肢截面,并在双肢间设置BRB)为该桥最优措施。 相似文献
653.
A moving sidewalk system installed at an airport pier finger is analyzed. The optimal length of the moving sidewalk and the optimal spacing between the access points which minimize the total cost of the system are obtained using methods of calculus, for a number of cases based on the different proportions of arriving, departing and transferring passengers and for two different types of moving sidewalks: elevated, at‐grade. The optimal length of the moving sidewalk is shown to be linearly related to the length of the concourse, and to the total passenger demand. The effect due to preticketed transferees is insignificant. The optimal spacing between access points is shown to be proportional to the square‐root of either the cost of an access escalator or the cost of inconvenience to a passenger due to an intermediate gap, depending on the moving sidewalk system under consideration. It also changes with the percentage of preticketed transferees. 相似文献
654.
In an earlier work, Sun and Bayen built a Large-Capacity Cell Transmission Model for air traffic flow management. They formulated an integer programming problem of minimizing the total travel time of flights in the National Airspace System of the United States subject to sector capacity constraints. The integer program was relaxed to a linear program for computational efficiency. In this paper the authors formulate the optimization problem in a standard linear programming form. We analyze the total unimodular property of the constraint matrix, and prove that the linear programming relaxation generates an optimal integral solution for the original integer program. It is guaranteed to be optimal and integral if solved by a simplex related method. In order to speed up the computation, we apply the Dantzig–Wolfe Decomposition algorithm, which is shown to preserve the total unimodularity of the constraint matrix. Finally, we evaluate the performances of Sun and Bayen’s relaxation solved by the interior point method and our decomposition algorithm with large-scale air traffic data. 相似文献
655.
上海开始了新一轮城市总体规划,而市郊轨道交通网络规划对城市总体规划影响很大。为了给上海都市圈市郊轨道交通网规划提供启发,选择了与上海有可比性的东京都市圈作为研究对象,较深入地剖析了东京都市圈市郊轨道交通的供需特征;分圈层比较了东京都市圈与上海都市圈的相关统计数据,得到了东京都市圈郊区圈层的4类轨道交通的长度及放射线、周向线的供给分布特征和郊区圈层的径向、周向及过境出行需求特征,以及供需二者之间的关系特征。在此基础上得到启示,对上海都市圈市郊轨道交通网规划提出了建议。 相似文献
656.
Md. Tazul Islam 《运输规划与技术》2013,36(4):409-426
Abstract Trip chaining (or tours) and mode choice are two critical factors influencing a variety of patterns of urban travel demand. This paper investigates the hierarchical relationship between these two sets of decisions including the influences of socio-demographic characteristics on them. It uses a 6-week travel diary collected in Thurgau, Switzerland, in 2003. The structural equation modeling technique is applied to identify the hierarchical relationship. Hierarchy and temporal consistency of the relationship is investigated separately for work versus non-work tours. It becomes clear that for work tours in weekdays, trip-chaining and mode choice decisions are simultaneous and remain consistent across the weeks. For non-work tours in weekdays, mode choice decisions precede trip-chaining decisions. However, for non-work tours in weekends, trip-chaining decisions precede mode choice decisions. A number of socioeconomic characteristics also play major roles in influencing the relationships. Results of the investigation challenge the traditional approach of modeling mode choice separately from activity-scheduling decisions. 相似文献
657.
A macroscopic taxi model for passenger demand,taxi utilization and level of services 总被引:1,自引:0,他引:1
In most urban areas taxi services are subject to various types of regulation such as entry restriction and price control.
However, effective intervention depends on generating and using suitable information on the demand-supply equilibrium of the
taxi market. This paper develops a simultaneous equation system of passenger demand, taxi utilization and level of services
based on a taxi service situation found in the urban area of Hong Kong over the last ten years. A set of variables is introduced
including number of licensed taxis, taxi fare, disposable income, occupied taxi journey time as exogenous variables and daily
taxi passenger demand, passenger waiting time, taxi availability, taxi utilization and average taxi waiting time as endogenous
variables. These variables are coupled together through a system of nonlinear simultaneous equations whose parameters are
estimated from survey data. The simultaneous equation system can be used to obtain useful regulatory information to assist
with the decisions concerning the restriction over the number of taxi licenses and the fixing of the taxi fare structure as
well as a range of service quality control.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
658.
659.
针对某中型客车,利用ADAMS软件建立了空气悬架客车动力学仿真模型,并进行了随机路面输入及三角凸台路面输入的平顺性仿真分析。仿真结果与试验数据对比表明,在测量点处的最大加速度、自功率谱密度及其对应的频率点比较接近,说明所建立的仿真模型是准确的。对影响客车平顺性的2个参数在ADAMS中进行了优化。 相似文献
660.