A Green Vehicle Routing Problem

A Green Vehicle Routing Problem (G-VRP) is formulated and solution techniques are developed to aid organizations with alternative fuel-powered vehicle fleets in overcoming difficulties that exist as a result of limited vehicle driving range in conjunction with limited refueling infrastructure. The G-VRP is formulated as a mixed integer linear program. Two construction heuristics, the Modified Clarke and Wright Savings heuristic and the Density-Based Clustering Algorithm, and a customized improvement technique, are developed. Results of numerical experiments show that the heuristics perform well. Moreover, problem feasibility depends on customer and station location configurations. Implications of technology adoption on operations are discussed.     

The time dependent vehicle routing problem with time windows: Benchmark problems, an efficient solution algorithm, and solution characteristics

An algorithm that can tackle time dependent vehicle routing problems with hard or soft time windows without any alteration in its structure is presented. Analytical and experimental results indicate that average computational time increases proportionally to the number of customers squared. New replicable test problems that capture the typical speed variations of congested urban settings are proposed. Solution quality, time window perturbations, and computational time results are discussed as well as a method to study the impact of perturbations by problem type. The algorithm efficiency and simplicity is well suited for urban areas where fast running times may be required.     

A new approach to travel information sources and travel behaviour based on cognitive dissonance theory

This study examines the influences of en route information on travel behaviours, based on cognitive dissonance theory, which explains that selective exposure to new information leads to the presence of dissonance. Fifteen travel activities were identified from the related literature to measure levels of unplanned travel behaviours. Moreover, two types of information sources used during trips were tested to evaluate the degree of dissonance in accordance with new information provided to travellers while on vacation. The results indicated that during trips, those who use information technology change their intended behaviours, while those who use ‘traditional’ information sources actualize their intended behaviours. In line with cognitive dissonance theory, information technology is viewed as dissonance-increasing information, while traditional information sources used during trips are considered consonance-increasing information.     

Vehicle routing optimization with soft time windows in a fuzzy random environment

This paper is concerned with a vehicle routing problem with soft time windows (VRPSTW) in a fuzzy random environment. Two objectives are considered: (1) minimize the total travel cost and (2) maximize the average satisfaction level of all customers. After setting up the model for the VRPSTW in a fuzzy random environment, the fuzzy random expected value concept is used to deal with the constraints and its equivalent crisp model is derived. The global–local–neighbor particle swarm optimization with exchangeable particles (GLNPSO-ep) is employed to solve the equivalent crisp model. A case study is also presented to illustrate the effectiveness of the proposed approach.     

A novel methodology for designing a household waste collection system for insular zones

This paper addresses the problem of designing a household waste collection system for rural insular areas using a barge for transportation, based on a novel mixed integer programming model that simultaneously integrates decisions of waste collection sites selection within the islands to be served, visit schedule for each selected collection site, and multi-period vehicle routing. An application to a real-world instance consisting of small rural islands located in the south of Chile shows the effectiveness and complexity of the model, along with the advantages of using a waste compactor instead of transporting the waste using bins onboard a barge.     

Travel time use and its impact on high-speed-railway passengers' travel satisfaction in the e-society

The availability of wireless networks and the pervasive use of mobile ICT devices have allowed passengers to conduct various e-activities during journeys. These various e-activities, in turn, may change people's conventional perception of travel time from being “wasteful” and “unproductive,” to “desirable” and giving rise to satisfaction. Journeys on high-speed railway (HSR) is particularly relevant for transport researchers to probe into this question because of its characteristics of being medium to long-distance (typically taking half-an-hour or more), seat availability, and a smooth ride. Using a questionnaire survey on passengers along the Shanghai-Nanjing HSR route, this study aims to examine the nature of ICT device use and in-vehicle e-activities conducted by HSR passengers and the influence on their travel satisfaction with their on-board journey experience. Our results reveal a high percentage of ICT device use and a wide variety of e-activities such as e-working, e-communication, and e-reading for leisure on HSR trains. In addition, the higher use of ICT device was associated with an increase of passengers' travel satisfaction. Furthermore, we found a positive effect of work-related e-activities on travel satisfaction for business/work trips, while a positive effect of entertainment-related e-activities for non-business/work trips. Given that HSR is potentially a more sustainable transport mode, some possible policy implications are proposed to encourage people to use HSR, as opposed to driving or flying, for medium to long-distance intercity journeys.     

突发事件下的车辆路径问题研究综述

车辆路径问题是物流管理研究中的一项重要内容。概述突发事件下车辆路径问题研究的背景和意义,介绍车辆路径问题的衍化分类,针对突发事件下车辆路径问题的特点,综述国内外研究现状。重点探讨突发事件下车辆路径问题的研究范围和前景。     

Do people consider an acceptable travel time? Evidence from Berkeley,CA

This paper explores the extent to which people identify an acceptable travel time for each trip they want to make and investigates the primary characteristics of this behavioural threshold. We assume that an acceptable travel time is defined through utilitarian processes that are related to cognitive and affective evaluations of travel that develop throughout a person’s lifetime. We apply a mixed methods approach to explore our hypothesis, based on semi-structured in-depth interviews with a stratified, according to commuting mode, random sample of 20 individuals living in Berkeley, CA. Our results support the validity of the acceptable travel time concept and offer (a) initial evidence on its variation to the travel mode and sociodemographic characteristics and (b) insights into people’s perceptions, attitudes, feelings and experiences about their travel. Thus, our results can contribute to a better understanding of individuals’ travel decisions and valuation of travel time and can inform time–space and accessibility research.     

应急物流配送问题的蚁群聚类算法研究

提出了一种用于解决突发事件下,物流配送多目标优化问题的蚁群聚类优化算法。突发事件下的物流配送规划一般包含两方面内容,将救灾物资运往受灾地区和将灾区的伤员及时送至各医疗点。将多目标问题转化为单目标问题,结合蚁群的墓地构造行为特点,利用改进LF蚁群聚类模型,以节点需求未得到满足的不满意度最小和路由时间最短为优化目标,用LF蚁群聚类方法按约束条件进行聚类,最终确定车辆路由线路。     

Valuation of travel time for international long-distance travel – results from the Fehmarn Belt stated choice experiment

The geographical scope of travel varies from short distances in urban areas to long distances across cities and countries. While urban travel has been widely analysed in the literature, travel over longer distances and particularly across countries, has received much less attention. While this may be justified due to the number of travellers it cannot be justified when looking at the mileage consumption and its resulting environmental impacts. In this paper, we investigate international long-distance travel preferences related to travel between Scandinavia and Central Europe with particular focus on the Fehmarn Belt fixed link between Germany and Denmark to be opened in 2021. To facilitate long-term demand forecasts for the future fixed link, stated preference data were collected in 2011. Based on these data a discrete choice model for long-distance travellers was developed in order to estimate the value of travel time savings (VTTS). The final model, which was formulated as a nested logit model and included Box–Cox transformed travel time and cost attributes, revealed several interesting findings. Firstly, we found damping effects in both cost and time – most strongly in cost. Secondly, we found significant interactions among travel cost and time, and journey characteristics, such as distance and duration. This had direct impact on the VTTS, which was shown to decrease with distance and duration. Thirdly, we found that air travel implies a higher average VTTS, which is to be expected but rarely supported by empirical evidence.     

交通事故引起的排队长度及消散时间的估算

传统的排队论理论单纯使用需求量和通行能力关系推算排队长度,由于其未考虑车流波动的影响,从而使估算结果与实际出入很大。现用车流波动理论分析发生交通事故后路段上车辆排队的形成与消散过程,推导出估算排队长度与消散时间的公式,并通过算例说明根据估算值提前分流,可提高道路的通行能力。     

Locating road-vehicle refueling stations

This study follows the concept of set cover for proposing a refueling-station-location model using a mixed integer programming method, based on vehicle-routing logics. Its solution uses only the easy-obtain data of the origin-destination distance matrix. A case study that focuses on the siting of refueling stations for achieving multiple origin-destination intercity travel via electric vehicles on Taiwan demonstrates the applicability of the model. Sensitivity analysis shows that greater vehicle range will result in a lower number of refueling stations that need to be sited. Range is crucial in reducing the facility-location costs, and therefore is an important issue in the development of alternative-fuel-vehicle technology.