Activity based travel demand models as a tool for evaluating sustainable transportation policies

India is in the course of an economic transition. The economic growth nurtured the life in the cities and cities have become a major livelihood destination for everyone. This migration of people contributed to the increased urbanization of Indian cities. The booming economy fostered the well-being and shaped the lifestyle of people in such a way that the dependency on private vehicle has become an unavoidable affair. Along with population growth, the increased vehicle ownership gave rise to overall spurt in travel demand. But the supply side lagged behind the demand adding to many of the transport related externalities such as accidents, congestion, pollution, inequity etc. The importance of sustainability is understood in the current urban transport scenario leading to the development and promotion of sustainable transport polices. The core agenda of these polices is to target the travel behavior of people and change the way they travel by creating a different travel environment. However, the impacts of many such policies are either unknown or complex. Hence, before adopting and implementing such policies, it is important for the decision makers to be aware of the impacts of them. The role of travel demand models comes here as they predict the future travel demand under different policy scenarios. This paper reviews the ability of travel demand models applied in India in analyzing the sustainable transport policies. The study found that the conventional model system in India, which is trip based four step aggregate methodology, is inadequate in analyzing the sustainable transport policies. A review of alternative approach, known as activity based travel demand modeling found that they are capable of handling such policies better than conventional models and are assistive to the decision makers in arriving at right mix of polices specific to the situations. Since there is no operational activity based travel demand model system developed in India, the study at the end envisaged a conceptual framework of an integrated activity based travel demand model based on the requirements identified from the review. This can potentially replace the existing travel demand models and can be used for planning applications once the modification & validation have been done according to the existing activity-travel behavior of individuals.     

船舶操纵性评价的灰关联分析和逼近理想解法

针对船舶操纵性评价中存在的问题,在深入研究各种系统评价方法的基础上,提出了一种基于灰关联分析和逼近理想解法(TOPSIS)的船舶操纵性能综合评价方法.该方法运用灰关联分析理论,计算评价指标的灰绝对关联度及评价指标的权重;利用TOPSIS法,建立加权评价矩阵,引入Hausdorff距离代替欧式距离,计算各评价对象与理想方案的相对接近度,并依据相对接近度对各参评船型的操纵性作出优劣排序.应用结果表明,该方法合理有效,实用性强.     

Distributions of travel time variability on urban roads

Reliability is an important factor in route, mode and also departure time choice analysis and is a key performance indicator for transport systems. However, the current metrics used to measure travel time variability may be not sufficient to fully represent reliability. Better understanding of the distributions of travel times is needed for the development of improved metrics for reliability. A comprehensive data analysis involving the assessment of longitudinal travel time data for two urban arterial road corridors in Adelaide, Australia, demonstrates that the observed distributions are more complex than previously assumed. The data sets demonstrate strong positive skew, very long upper tails, and sometimes bimodality. This paper proposes the use of alternative statistical distributions for travel time variability, with the Burr Type XII distribution emerging as an appropriate model for both links and routes. This statistical distribution has some attractive properties that make it suitable for explicit definition of many travel time reliability metrics. Copyright © 2011 John Wiley & Sons, Ltd.     

Evaluation of different contraflow strategies for hurricane evacuation in Charleston,South Carolina

Abstract

Limited specific evidence is available on the effectiveness of using contraflow as an evacuation traffic management tool. This study was conducted to determine the best combination of strategy options for evacuating Charleston, SC, along route I-26 during the event of a hurricane or other events. PARAMICS microscopic traffic simulator was used to evaluate the impact of each combination of evacuee response timing and traffic control strategy, such as contraflow, with respect to average vehicular travel time and evacuation duration. Analysis revealed the combination of management strategies that created the lowest evacuation durations and travel times for several types of anticipated evacuee responses. Furthermore, a proposed reconfiguration of the I-526/I-26 interchange for contraflow operations produced additional savings in travel times and evacuation durations. These findings support the use of all lanes for contraflow during all evacuations and provide justification to examine a possible reconfiguration of the I-526/I-26 interchange for use during evacuations.     

Risk aversion,regret aversion and travel choice inertia: an experimental study

This paper presents the results of an experimental study into the role of risk aversion and regret aversion as codeterminants of travel choice inertia. Theoretical results published by Chorus and Dellaert are tested empirically. More specifically, the expectation is tested that when (1) travelers are risk averse, (2) the quality of travel choices is uncertain, and (3) the quality is partially revealed upon usage, travel choice inertia emerges as a learning-based lock-in effect. In addition, this paper studies the role of regret aversion as a possible trigger of travel choice inertia. Analyses are based on data collected in an experiment, where the reward that participants obtain is a function of the outcome of choices they make. Empirical results suggest that the learning-based lock-in effect indeed plays a role in the context of our data. The evidence for the hypothesis that regret aversion triggers inertia is mixed at best.     

Short-term impact analysis of fuel price policy change on travel demand in Malaysian cities

Abstract

Malaysia is one of the few countries in the world that provides a fuel subsidy to consumers. Due to the recent economic crisis, the Malaysian Government decided to revise its fuel subsidization policy from a fixed price subsidy to a floating price subsidy dependent on global oil demand. Recognizing that the change in fuel subsidization policy can have an impact on travel behavior, this article investigates the short-term impact of the policy change on private and public transportation in the Klang Valley region of Malaysia. Spectral analyses are performed to investigate if the policy change has an impact on private vehicle travel demand, measured in terms of road traffic, and short-term travel demand elasticity with respect to fuel price is estimated. To measure the impact on the public transportation system, the demand cross-elasticity values of rail transit and buses are also estimated. It was found that traffic flow reduces with an increase in fuel price, although elasticity and cross-elasticity values obtained are low. The article finds that there is a potential mode shift from private vehicles to rail transit with increasing fuel price. It is demonstrated that reducing fuel price subsidy can be an effective travel demand management strategy to alleviate congestion.     

覆盖层次结构的知识距离刻画方法

为了研究覆盖上的层次结构问题,在覆盖上提出了知识距离的概念,并由覆盖知识距离构建了两种不同的代数格,最终使用由这两种代数格所诱导出的偏序关系来刻画不同覆盖之间的关系.实例分析表明由知识距离格方法来研究覆盖的层次问题是切实可行的.由此可以看出,知识距离为研究覆盖的层次问题提供了一种新的有效方法.     

Enablers and Barriers to the Adoption of Alternatively Powered Buses

Abstract

This paper seeks to identify enablers and barriers that stimulate or prevent the adoption of alternatively powered buses (APBs) in cities. The research method concentrates on an in‐depth analysis of 21 European demonstration case studies of APBs. Considerable differences exist between these cities due to the different reference situation. The type of measurement and the situation in the demonstration cities influence the exact fuel consumption and emission reduction. Variables that could enable the adoption of all types of APBs are: (1) the compatibility with previously introduced ideas; (2) the already available necessary supporting infrastructure in the city; (3) a changed external appearance of the APB; (4) the acceptance of the APBs by passengers and bus drivers; and (5) political support in the city regarding the APBs. The main variables that could be determined as barriers are: the relative economic advantage (the outline of costs is higher than that of conventional buses); and the understanding of the APB for bus drivers and mechanics (because special training is needed for both groups).     

Promoting Cycling for Transport: Research Needs and Challenges

Abstract

Near future travel-time information is one of the most critical factors that travellers consider before making trip decisions. In efforts to provide more reliable future travel-time estimations, transportation engineers have examined various techniques developed in the last three decades. However, there have not been sufficiently systematic and through reviews so far. In order to effectively support various transportation strategies and applications including Intelligent Transportation Systems (ITS), it is necessary to apply appropriate forecasting methods for matching circumstances in a timely manner. This paper conducts a comprehensive review study focusing on literatures, including modern techniques proposed recently, related to travel time and traffic condition predictions that are based on ‘data-driven' approaches. Based on the underlying mechanisms and theoretical principles, different approaches are categorized as parametric (linear regression and time series) and non-parametric approaches (artificial intelligence and pattern searching). Then, the approaches are analysed for their strengths, potential weaknesses, and performances from five main perspectives that are prediction range, accuracy, efficiency, applicability, and robustness.     

Seventy Minutes Plus or Minus 10 — A Review of Travel Time Budget Studies

Abstract

This paper provides a comprehensive review of travel-time budget (TTB) studies in the literature for about the past four decades. Starting with the concept of TTBs, it discusses both the studies that support the existence of TTB and also those that deem the concept to be unfounded. Sociodemographic variables and their relation to TTB are also discussed briefly. However, as past studies use different data sources, survey techniques, and methodology for analysis, cross comparison of studies is not possible. Most importantly, the underlying cause of the regularity that is found at an aggregate level is still not known. The idea of TTB is important because, if it exists, it would mean that the total time spent on travelling per person per day will remain unchanged in spite of all improvements to transport. TTB has immense implications for transport policies and it is usually ignored. The paper also explores the available theoretical explanation of this concept, past research gaps and new analysis potentials. Recent directions in TTB studies are also discussed together with the potential use of multiday multiyear panel data in TTB research to explore the phenomenon better than before.