Design and evaluation of an integrated inventory and transportation system

This paper proposes the adoption of an integrated inventory and transportation system (IITS) to minimize the total costs of inventory and transportation. A non-linear programing is developed by analyzing transportation and inventory costs with one supplier and many retailers in the distribution environment. The paper compares the proposed model with the traditional approach in computing total costs with numerical data. The results indicate that the total costs can be optimized by adopting integrated programing rather than the traditional approach, along with achieving improved customer service levels. In particular, sensitivity analysis is applied to determine the performance of the IITS under various transportation costs, holding costs and shortage costs. It shows that the transportation cost per unit is most sensitive in the proposed model. In this situation, the IITS is more effective for cost saving when set-up cost, holding and shortage costs are high, but is less effective for situations involving high per-unit transportation costs.     

A zone design methodology for national freight origin–destination data and transportation modeling

The zone system used for freight data collection and the geographic resolution of published data has a significant impact on analysis and planning. The majority of existing freight model zones are created in an ad hoc way. In this paper, a new model-based design method is introduced to develop freight zones for the continental USA. It focuses on two methodology issues: (1) the criteria that represent the desired properties of a zone system and (2) the constraints that govern the shape, size, and continuity of zones. The method is applied to the continental USA by optimizing an interzonal travel distance weighted by freight flows using county-level freight data. Several optimal national-level freight zone systems with different numbers of zones are developed. The results indicate that a 300-zone system provides a balance between the number of zones and optimization measures where the currently available public freight data are provided with approximately 100 zones.     

Effects of economic disincentives on private car use

A field experiment was conducted to investigate the effects of economic disincentives on private car use. Eighty two-adult households who were owners of at least one car were randomly assigned to three experimental groups and one control group. Both experimental and control groups logged their car trips during one week before, one week during, and one week after treatment. The treatment consisted of charging two of the experimental groups approximately 100% of normal cost per kilometer of driving during 2 weeks, and charging the third experimental group this amount per kilometer of driving during 4 weeks. With the purpose of investigating whether deliberate planning increases the effect of economic disincentives, the households in one of the former and in the latter group were asked to fill out a prospective car log for the following week. The control group was not charged or requested to fill out a prospective car log but was in other respects treated in the same way. Analyses of the car logs and odometer readings during and at the end of treatment showed a weak reduction of car use due to the economic disincentives that however were almost completely dependent on planning.     

A new approach for improving the performance of freight train timetabling of a single-track railway system

A new approach for improving the performance of freight train timetabling for single-track railways is proposed. Using the idea of a fixed-block signaling system, we develop a matrix representation to express the occupation of inter- and intra-station tracks by trains illustrating the train blocking time diagram in its entirety. Train departure times, dwell times, and unnecessary stopping are adjusted to reduce average train travel time and single train travel time. Conflicts between successive stations and within stations are identified and solved. A fuzzy logic system is further used to adjust the range of train departure times and checks are made to determine whether dwell times and time intervals can be adjusted for passenger and freight trains at congested stations to minimize train waiting times. By combining manual scheduling expertise with the fuzzy inference method, timetable efficiency is significantly improved and becomes more flexible.     

基于客户满意度的货运动车组开行方案研究

高铁货运逐渐兴起,本文对货运动车组开行方案优化进行了研究。针对高铁运输安全、快捷、运输成本较低等特性,提出以货运动车组及客货混编动车组为主,客运动车组捎带运输为补充的开行模式,结合运输需求、线路通过能力等限条件,以运输成本最小和货主满意度最大为目标,建立多目标综合优化模型,运用线性加权组合法,以lingo软件为依托进行求解。通过算例给出具体开行方案,并对同一运输区间各种运输方式的单位成本及用时进行对比分析。结果表明,相对于传统运输方式,高铁货运综合运输成本较低,用时更短,能够兼顾运输企业与货主的双重要求;所建模型优化效果明显,可为未来货运动车组的开行提供参考。     

货运车型标准化专项治理管理系统设计与实现

货运车型标准化是国家运输行业结构调整及货运行业提质增效发展的重要工作手段与目标。从货运车型标准化转型治理工作的功能需求出发,以正在开展的常压液体危险货物罐车治理工作为基础,本文设计并实现了基于SSM架构的货运车型标准化专项治理管理系统。危险货物道路运输企业在系统中申报罐车信息,罐车检验机构基于车辆识别代码上传罐检报告,道路运输管理机构通过对罐车信息及关键报告进行审核,给予审核结果及意见。     

基于新型轨道交通中节能环保型牵引飞行舱的研究

针对高速交通与低耗的矛盾问题,本文研究了一种基于飞行与轨道运行相结合的新型轨道交通工具--牵引飞行舱,通过牵引飞行舱的架构及牵引飞行舱的运行机理设计,从飞行舱自重减轻、飞行舱负荷转移、正面空气阻力减小、地面方向气阻降低4个方面实现了牵引飞行舱的节能特征,并使其具有较高的安全及环保属性。     

Tracks to Change or Mixed Signals? A Review of the Anglo-Saxon Literature on the Economic and Spatial Impacts of High-Speed Rail

ABSTRACT

The economic development and spatial impacts of high-speed rail (HSR) are quite varied and mixed. Studies of economic impacts of HSR fall into two categories: predictions and empirical observations. We first review studies that examine predicted HSR impacts related to job growth, real estate development, and other economic effects. These are followed by studies examining observed effects of realized projects using the same categories. Several patterns emerge. Predictive studies are largely optimistic of the rail's positive effects. On the other hand, observational studies tend to identify both benefits and shortfalls. Yet, neither of these patterns are universal and depend on a number of other factors. One consistent pattern is that gains associated with HSR appear to be stronger in first-tier cities. Nevertheless, certain small towns and second-tier cities have undergone noteworthy transformations as a result of HSR, especially where the public sector has actively pursued new investment.