Determining the optimal number of seasonal adjustment factor groupings when estimating annual average daily traffic and investigating their characteristics

Although cluster analysis is recommended by the US Traffic Monitoring Guide (TMG) to supplement the development of seasonal adjustment factor groupings (SAFGs), the relationships among SAFGs' characteristics remain undiscovered, while the determination of the optimal number of clusters is an ambiguous task exposed to great subjectivity. Statistical indicators provide a mathematical solution by removing engineering judgment without taking into consideration any guidelines or other criteria, necessary for transportation planners to generate ‘practical and sensible’ groupings. The method examined in this study aims to overcome the above weaknesses incorporating into the methodology a series of statistics, recommendations, and previous research findings. The investigation of the relationships among (1) the within-group variation, (2) the total number of sites, (3) the minimum number of stations within a cluster, (4) the optimal number of clusters, and (5) the geographical size of the groups constitutes the main objectives of this research. According to the results, the cluster variability declines as the available number of stations increases. When the minimum number of stations within a cluster increases, the weighted coefficient of variation inflates as well, with the rate of increase depending on sample size. The average number of automatic traffic recorders per cluster is analogous to the sample size, while the optimal number of clusters varies conversely with the minimum number of stations within a cluster. The application developed for the conduct of the analysis minimizes the computational time needed, while it can be easily implemented by engineers to automate the process recommended by the TMG, enhancing the current state of practice.     

Impacts of commuting efficiency on congestion and emissions: case of the Hamilton CMA, Canada

This study uses IMULATE (Integrated Model of Urban LAnd use, Transportation, energy and Emissions) to examine the impacts of commuting efficiency on congestion and automobile emissions—specifically, non-methane hydrocarbons, carbon monoxide and nitrogen oxides—in the Hamilton Census Metropolitan Area. Estimates of these externalities are compared for two commuting scenarios: a base scenario of estimated commuting flows for 1991 and an optimal scenario in which the mean commuting time for all workers is minimized. The findings indicate that significant reductions in congestion and automobile emissions are possible by advocating policies that encourage greater commuting efficiency in the locational choices of workers. The analysis of jobs–housing balance as one such means suggests that a considerable proportion of commuting cannot be explained by geographical imbalances in the distributions of jobs and housing, and that workers consider many factors besides commuting costs in their locational choices. It is concluded that policies promoting jobs–housing balance as the principal strategy for facilitating more efficient commuting may not meet the expectations of policy-makers.     

The Mixed Logit model: The state of practice

The mixed logit model is considered to be the most promising state of the art discrete choice model currently available. Increasingly researchers and practitioners are estimating mixed logit models of various degrees of sophistication with mixtures of revealed preference and stated choice data. It is timely to review progress in model estimation since the learning curve is steep and the unwary are likely to fall into a chasm if not careful. These chasms are very deep indeed given the complexity of the mixed logit model. Although the theory is relatively clear, estimation and data issues are far from clear. Indeed there is a great deal of potential mis-inference consequent on trying to extract increased behavioural realism from data that are often not able to comply with the demands of mixed logit models. Possibly for the first time we now have an estimation method that requires extremely high quality data if the analyst wishes to take advantage of the extended behavioural capabilities of such models. This paper focuses on the new opportunities offered by mixed logit models and some issues to be aware of to avoid misuse of such advanced discrete choice methods by the practitioner.     

车钩改进与互换的管理

在美国,车钩几乎是铁路装备中既要受美国联邦铁路管理委员会管理,又要受美国铁路协会监督的仅有部件,要求各制造商生产的车钩必须具有良好的互换性。这一要求适用于车钩的几乎每一单件,即钩舌、钩锁和钩体。机、货车的可靠连接完全取决于整个车钩的互换性。这一要求使得ABC     

车辆用缓冲装置

介绍了近10年来缓冲装置的发展情况,以及几个供货商研究开发的车钩缓冲装置。     

正确认识牵引杆的选择

介绍了无间隙牵引杆和关节连接器在北美货车联运中的运用情况,比较分析了其与常规车钩缓冲装置运用上的互换性和可维修性,同时阐述了牵引杆的结构特点和性能特征。     

How to Retreat: The Necessary Transition from Buyouts to Leasing

Abstract

Moving assets out of vulnerable areas, known as “retreat,” is a necessary but unpopular option when coastal hazards impact land. Most people prefer protection options. Governments and private land owners tend to adopt a “wait-and-see” approach for retreat. This may be because the time for retreat seems some way off, or because protection has not yet been ruled out, or to avoid unwelcome news. This policy void has allowed people to assume that government will offer to “buyout” property on generous terms after coastal hazards inevitably force the owner to relocate. The problem with that assumption is that (a) it is unaffordable as a solution for all at-risk properties and (b) it acts as an incentive to intensify development in locations vulnerable to coastal hazards. It is, in effect, a form of market distortion which promotes maladaptive behavior. We therefore need to retire that assumption by articulating a standard default arrangement for retreat. This essay suggests that government should establish a default position of renting land, rather than acquiring it, once assets are abandoned by private land owners. This provides sufficient leverage to protect the public interest and a level of financial assistance to the relocating land owner, while allowing markets to properly reflect risk and enabling coastal adaptation.     

下一代新型货车

介绍了美国几家主要货车制造商开发的新型有盖漏斗车、双层棚车、大载重平车、铝合金煤炭漏斗车、双层汽车运输车、冷藏车和可交换车体货车等车型的主要特点和结构参数,其共同目标是延长车辆寿命、减轻车辆自重、提高有效运载能力.     

THE CHANGES OF BONE VOLUME AND TURNOVER IN POSTMENOPAUSAL WOMEN WITH OSTEOPOROSIS：A REPORT OF 293 BONE BIOPSIES

ＴＨＥＣＨＡＮＧＥＳＯＦＢＯＮＥＶＯＬＵＭＥＡＮＤＴＵＲＮＯＶＥＲＩＮＰＯＳＴＭＥＮＯＰＡＵＳＡＬＷＯＭＥＮＷＩＴＨＯＳＴＥＯＰＯＲＯＳＩＳ：ＡＲＥＰＯＲＴＯＦ２９３ＢＯＮＥＢＩＯＰＳＩＥＳＺｈｕＪｉａｎｍｉｎ；ＷｉｌｌｉａｍＥ．Ｈｕｆｆｅｒ，Ｐａｔ...     

A reliability‐based traffic assignment model for multi‐modal transport network under demand uncertainty

In densely populated and congested urban areas, the travel times in congested multi‐modal transport networks are generally varied and stochastic in practice. These stochastic travel times may be raised from day‐to‐day demand fluctuations and would affect travelers' route and mode choice behaviors according to their different expectations of on‐time arrival. In view of these, this paper presents a reliability‐based user equilibrium traffic assignment model for congested multi‐modal transport networks under demand uncertainty. The stochastic bus frequency due to the unstable travel time of bus route is explicitly considered. By the proposed model, travelers' route and mode choice behaviors are intensively explored. In addition, a stochastic state‐augmented multi‐modal transport network is adopted in this paper to effectively model probable transfers and non‐linear fare structures. A numerical example is given to illustrate the merits of the proposed model. Copyright © 2012 John Wiley & Sons, Ltd.