Impact of regional population density on walking behavior

Land use can influence walking (measured by the number of steps) and so the health of people. This paper presents the result of empirical research on the impact of regional population densities (inhabitants per inhabitable area) on the number of steps (all steps, both outdoors and indoors). With data collected from almost 11,000 respondents in 148 Japanese regions, we estimate polynomial regression models, the total number of steps being the dependent variable and densities being the main independent variable. Regional population density significantly affects the number of steps after controlling for individual and household attributes. The estimated population density that maximizes the number of steps is around 11,000?persons/km². Increasing densities, up to levels of around 11,000?inhabitants/km², could increase walking and consequently the health of inhabitants. The population density elasticity of the number of steps is 0.046–0.049 in a simple log linear regression model without a peak.     

Travel time prediction and departure time adjustment behavior dynamics in a congested traffic system

This paper examines two heuristic rules proposed for describing urban commuters' predictions of travel time as well as the adjustments of departure time in response to unacceptable arrivals in their daily commute under limited information. It is based on the notion that the magnitude of the predicted travel time depends on each commuter's own experience, including recallable travel time, schedule delay, and difficulties in searching for a satisfactory departure time. An explanatory analysis is first performed to compare these two rules, based on the information provided by a set of commuters interacting over 24 days through a simulated traffic system. A more elaborate model specification which captures the dynamic interrelation between the commuter's cumulative and recent experience with the traffic system's performance is then proposed. The model parameters are estimated with explicit consideration of the serial correlation arising from repeated decisions by the same individuals and the contemporaneous interaction with other system users' decisions through the traffic system's performance.     

Travel itinerary problem

In this study, we propose a travel itinerary problem (TIP) which aims to find itineraries with the lowest cost for travelers visiting multiple cities, under the constraints of time horizon, stop times at cities and transport alternatives with fixed departure times, arrival times, and ticket prices. First, we formulate the TIP into a 0–1 integer programming model. Then, we decompose the itinerary optimization into a macroscopic tour (i.e., visiting sequence between cities) selection process and a microscopic number (i.e., flight number, train number for each piece of movement) selection process, and use an implicit enumeration algorithm to solve the optimal combination of tour and numbers. By integrating the itinerary optimization approach and Web crawler technology, we develop a smart travel system that is able to capture online transport data and recommend the optimal itinerary that satisfies travelers’ preferences in departure time, arrival time, cabin class, and transport mode. Finally, we present case studies based on real-life transport data to illustrate the usefulness of itinerary optimization for minimizing travel cost, the computational efficiency of the implicit enumeration algorithm, and the feasibility of the smart travel system.     

Role of the Travel Factor Convenience in Rail Travel and a Framework for its Assessment

Abstract

This paper reviews the travel factor convenience with particular regard to rail travel. Past research has shown that convenience is a concept readily associated with the private car and its perceived ability to provide a door‐to‐door journey. Private vehicles such as cars are often key competitors to public transport. However, convenience with regard to public transport has proved to be somewhat of an ambiguous concept, often showing a high degree of overlap with the other main recognized travel factors. This paper shows that it is possible to consider convenience in rail travel as an embodiment of four themes: access/egress, station facilities/environment, frequency of service/scheduling and interchange between train services. A list of physically measurable elements can be produced relating to these four themes in order to assess the convenience of any particular station. A categorization process is proposed based upon the initial findings of a questionnaire designed to obtain a user perspective upon convenience. It is concluded that no definitive measure of convenience can be produced for rail travel, although a proxy measure, based upon categorization, containing some or all of the defined elements should be possible.     

The Myth of Travel Time Saving

Abstract

The idea that the main benefit of improvements to transport infrastructure is the saving of travel time has been central to transport economic analysis. There is, however, little empirical evidence to support this proposition. Indeed, in the long run average travel time is conserved, implying that travellers take the benefit of improvements in the form of additional access to more distant destinations made possible by higher speeds. Such a perspective, based on considerations of the value of access, has implications for economic appraisal, modelling and policy.     

Tradeoffs between Time Allocations to Maintenance Activities/Travel and Discretionary Activities/Travel

This paper focuses on the tradeoff in time allocation between maintenance activities/travel and discretionary activities/travel. We recognize that people generally must travel a minimum amount of time in order to allocate one unit of time to the activity. This minimum amount of travel is represented by the travel time price, a ratio obtained by dividing the total amount of time traveling to maintenance or discretionary activities by the total amount of time spent on activities of the same type; it is the time equivalent of the monetary price for performing an activity. Using the San Francisco Bay Area 1996 Household Travel Survey data and applying the Almost Ideal Demand System (AIDS) of demand equations, we found that with respect to the time equivalent of income elasticities of maintenance and discretionary activities, the former is less than unity and the latter is greater than unity. In other words, maintenance activities are a necessity and discretionary activities are a luxury. With respect to the own travel time price elasticities, if the travel time price of performing a certain type of activity increases (for reasons such as traffic congestion), one would reduce the time allocated to that type of activity. Time spent on maintenance activities is less elastic than the time spent on discretionary activities. As for the cross travel time price elasticities (changes in time allocated to activity type i in responses to changes in the time price for activity type j), we found that ɛ_dm>0 and ɛ_md>0, suggesting a substitution effect between maintenance and discretionary activities.     

Unraveling the evacuation behavior of the medically fragile population: Findings from hurricane Irene

Despite the widely recognized importance of evacuation planning for residents with special needs – in this paper referred to as the medically fragile population – there is virtually no research available to guide such planning, as opposed to the numerous empirical research studies on the evacuation behavior of the general population. In this paper, we provide these long-overdue insights using data from a large-scale phone survey (over 7000 samples) conducted in the aftermath of hurricane Irene in the Hampton Roads region in Virginia. Via aggregate and disaggregate analyses, we start to unravel the behavior of this heavily understudied, and potentially vulnerable population group. Special emphasis will be placed on the differences between the medically fragile and non-medically fragile population. Two alternative definitions for what constitutes medically fragile are examined in this paper. Using the broader definition, it was found that a key difference between these two groups relates to the importance of having a strong network of family members in the area. When considering a more narrow definition, we found that being a single parent household, likelihood of neighborhood flooding and knowing most of the names of one’s neighbors have significantly different impacts on the two population groups.     

Travel behaviour and environmental concern

In two empirical studies, the impact of attitudes and environmental knowledge on driving distance, travel behaviour and acceptance of various traffic restrictions was investigated. The first study included the population in Lund, southern Sweden, and the second the politicians and civil servants responsible for transports and environment in the same city. Comparisons of the two samples revealed similar psychological processes, including environmental concern, hazard/efficacy perception and car affection, whereas environmental knowledge seemed to have a subordinate role. Preferences of restrictions differed somewhat between the public, and the politicians and civil servants. It is suggested that local implementation of new strategies to reduce private car driving might benefit from a better understanding of what will be accepted among the public. Further, in promoting pro-environmental travel behaviour it may be important to focus on basic attitudes, rather than to rely solely on factual information.     

Understanding Travel Time Expenditures Around the World: Exploring the Notion of a Travel Time Frontier

Travel behavior researchers have been intrigued by the amount of time that people allocate to travel in a day, i.e., the daily travel time expenditure, commonly referred to as a “travel time budget”. Explorations into the notion of a travel time budget have once again resurfaced in the context of activity-based and time use research in travel behavior modeling. This paper revisits the issue by developing the notion of a travel time frontier (TTF) that is distinct from the actual travel time expenditure or budget of an individual. The TTF is defined in this paper as an intrinsic maximum amount of time that people are willing to allocate for travel. It is treated as an unobserved frontier that influences the actual travel time expenditure measured in travel surveys. Using travel survey datasets from around the world (i.e., US, Switzerland and India), this paper sheds new light on daily travel time expenditures by modeling the unobserved TTF and comparing these frontiers across international contexts. The stochastic frontier modeling methodology is employed to model the unobserved TTF as a production frontier. Separate models are estimated for commuter and non-commuter samples to recognize the differing constraints between these market segments. Comparisons across the international contexts show considerable differences in average unobserved TTF values.     

老龄人口出行行为特征研究综述

人口老龄化对现存的交通系统和传统的交通规划、设计方法提出了巨大的挑战。本文的目的在于研究老龄人口的出行行为,为我国未来老龄化背景下的综合交通体系的建设、管理提供依据。本文通过综述国内外有关老龄人口出行的文献,对老龄人口的出行行为特征及其影响因素、出行对老龄人口的意义以及相应的交通对策进行对比分析研究,并在此基础上指出,今后应当结合我国老龄化社会的实际特点开展关于老龄人口的意愿出行需求分析与预测的方法理论研究。     

Travel time variability and airport accessibility

We analyze the cost of access travel time variability for air travelers. Reliable access to airports is important since the cost of missing a flight is likely to be high. First, the determinants of the preferred arrival times at airports are analyzed. Second, the willingness to pay (WTP) for reductions in access travel time, early and late arrival time at the airport, and the probability to miss a flight are estimated, using a stated choice experiment. The results indicate that the WTPs are relatively high. Third, a model is developed to calculate the cost of variable travel times for representative air travelers going by car, taking into account travel time cost, scheduling cost and the cost of missing a flight using empirical travel time data. In this model, the value of reliability for air travelers is derived taking “anticipating departure time choice” into account, meaning that travelers determine their departure time from home optimally. Results of the numerical exercise show that the cost of access travel time variability for business travelers are between 0% and 30% of total access travel cost, and for non-business travelers between 0% and 25%. These numbers depend strongly on the time of the day.     

Travel mode choice among same-sex couples

Same-sex partnered individuals are far more likely to use transit, walk, and cycle, and to a lesser extent, use carpools than are people in straight couples. As society becomes more tolerant, gay and lesbian populations are an increasingly visible social group, yet they have received scant attention by transportation scholars. This paper builds on this nascent literature by documenting and attempting to explain these dramatic differences by controlling for factors known to influence mode choice.We perform two separate analyses employing two distinct datasets. The first analysis examines journey-to-work data from the American Community Survey. The second analysis focuses in specifically on non-motorized (walking, biking) travel using use self-reported walk and bike frequency from the 2009 National Household Travel Survey. In both, we find that characteristics of the neighborhoods in which gays and lesbians live, as well characteristics of the individuals themselves, only explain part of the increased propensity to use “alternative” modes of transportation; a strong residual effect remains.     

客运专线超大断面隧道施工过程三维力学分析

客运专线上的隧道开挖断面积在150m2以上,必须选择合适的施工方法才能满足建设需要.对此,文章以Ⅳ级围岩为研究对象,根据隧道埋深的不同,对深埋情况下的台阶法和环形开挖留核心土法、浅埋情况下的CD法和CRD法等开挖方法进行了三维数值模拟;通过对超大断面隧道基本受力规律的分析比较,给出了适合于超大断面隧道的安全、经济、有效的施工方法.     

Travel behaviour and the total activity pattern

In the past years the behavioural basis of travel demand models has been considerably extended. In many cases individual behaviour is taken as the starting point of the analysis. Conventional aggregate models have been complemented by disaggregate models. However, even in most disaggregate models there is still the well-known sequence of generation, distribution, mode split, and assignment. In fact, travel behaviour is isolated from other human activities, and analyzed separately. The alternative is to take the general activity pattern of individuals as the departure point, and to consider travel as a derived demand. The basis of this study are diaries, kept during a full week on the basis of quarter hours by a sample of approximately 1100 persons.First, results with respect to travel frequency and travel time are given. Secondly, the influence of car availability and degree of urbanisation on travel behaviour is studied. Next, the population is divided into five person categories, and the travel pattern and activity pattern are studied separately per person group. Finally, links between travel and other activities are tentatively established.     

Travel demand functions for Florida bound tourists

This paper postulates functions for explaining and predicting tourist traffic to Florida. Traditional demand determinants, income and price, are included in the explanatory variable set, and two specifications of the functions are considered. Attention is confined to the auto and plane modes since they account for almost all Florida tourists. The equations are formulated in compliance with specific needs of the State. The data, which cover the period 1961I–1974II, are described in detail. Estimation of the demand equations involves the forty-six quarters ending 1972II with the remaining eight quarters reserved for ex post forecasting. These forecasting results are then compared with those from four naive models. Some effects of the energy crisis appear in the findings, and implications of the analysis for that issue are briefly discussed. Because of multicollinearity the functions are estimated by ridge regression. Straightforward application of ordinary least squares leads to theoretically incorrect algebraic signs in the auto equations and general imprecision in most equations. These anomalies are eliminated by a simple transformation of the data matrix according to the ridge criterion. Models of the type examined here can provide a geographic region with information on important aspects of its tourist population. They can also aid planners in the development of policy.     

Travel choices in alcohol-related situations in Virginia

Transportation - Using survey data from 3004 respondents aged 21 and older in Northern Virginia, Richmond, and the Tidewater area, this paper identifies factors associated with respondents’...     

Travel reduction strategies: intentions and outcomes

Continuing growth in travel has led to concerns about the environment and sustainability, and hence the need to attempt to reduce travel, particularly by car. This paper considers the types of travel reduction strategy available, in terms of the implicit mechanisms of switching or substitution by which travel would be modified or reduced, and evaluates their potential impacts by means of four case studies in European cities. It is found that the various travel reduction strategies have had qualified success. The strategies to some extent achieve reduction in car travel, mainly through switching to other modes, although also through reduced travel distance. However, the scale of the reduction is relatively small and may be offset by new traffic generation. In addition, in some cases the objectives of the measures, although potentially having a travel reduction contribution, are not always aimed directly at travel reduction as such, and therefore may not be able to deliver the intended travel reduction. The paper concludes that the way forward would appear to lie in setting clear policy objectives and in assembling travel reduction measures into strategy packages, ensuring that when combined the measures are complementary towards the policy objectives of travel reduction.