Book reviews

R. S. Farrow, with J. M. Broadus, T. A. Grigalunas, P. Hoagland III, and J. J. Opaluch. 1990. Managing the Outer Continental Shelf Lands: Oceans of Controversy. New York: Taylor & Francis New York, 168 pp., paper.

Richard A. Kenchington. 1990. Managing Marine Environments. New York: Taylor & Francis, 248 pp.     

Exploring the impacts of road surface texture on tyre/road noise - A case study in Hong Kong

The impacts of road surface texture on tyre/road noise are explored by analysing field data applying fast Fourier transform technique to tyre/road noise spectrum analysis. The results indicate that the tyre/road noise can be higher at lower frequency bands but lower at higher bands. Cluster analysis on surface texture in terms of wavelength identified three cluster groups that centred at 1.32 mm, 3.65 mm, and 5.11 mm have different impacts on noise. The shorter wavelength group suppressed tyre/road noise, medium group aggravated it and the high wavelength group were outliers.     

Demand Information from Incomplete Data—Application to Commercial Catfish

This paper provides general background information relating to the physical characteristics and operations of the Suez Canal. In connection with the future development of the Canal, the research programme currently being undertaken by a British consortium is outlined, with particular reference to the traffic system presently operating.     

Approach to assess a fast welding simulation in an industrial environment — Application for an automotive welded part

Fusion welding processes are widely used for joining metal structures, such as pipes, ships, and cars. In general, these joining processes offer a very good compromise between reliability, safety, cost and maintenance which are important issues in the current economical context. The negative heat effects of welding, i.e. distortions and residual stresses of the welded parts, are well known and many researches in this field have already been done in the last decades in order to minimize them. On the experimental side, many sophisticated procedures have become state of the art to deal with this problem. On the computational side, the improvement of the simulation algorithms and the computing power enables the simulations of many physical phenomena occurring during the welding process. The implementation of welding simulation techniques is nevertheless not an easy task and often associated with expert knowledge which hinders their global application in an industrial environment. This paper is focused on the industrial requirements of a welding simulation software with special respect to the needs of the automotive industry. The necessary information to run a welding simulation and the expectations of a weld specialist without deep knowledge in numerical methods are investigated. These expectations are tested on an automotive welded assembly with a commercially available welding simulation software designed especially for the needs of the automotive industry. A welding experiment is done and the measured temperature distributions and distortions serve as reference to validate the simulation results. The result quality of the simulations of temperature fields and distortions is in best agreement with experimental data. The workflow is well adapted for the considered industrial requirements and the time-tosolution as well as the computational costs are acceptable, whereas the efficient calibration of the heat input model is still a point which will be further investigated in current and future research works.     

Non-singular slip (NSS) method for longitudinal tire force calculations in a sudden braking simulation

In a dynamic vehicle simulation, longitudinal tire force is primarily based on the longitudinal slip (ratio). In the longitudinal slip formula, state variables are used in the denominator. This causes a divergence problem for numerical simulations of vehicle dynamics. To avoid this numerical singularity, a differential slip calculation method was developed for use in dynamic vehicle simulations. However, this method also causes a singularity when the wheel velocity approaches zero in a pure slip state, such as during sudden braking. In this paper, a new longitudinal slip calculation method, which can overcome singularities in all velocity conditions, is proposed. For this purpose, the Taylor series is adapted to the slip formula and the idea of virtual wheel rotation stiffness is introduced for the development of the slip equation. The physical phenomenon at the zero slip state is analyzed. Finally, the proposed slip formula is used to solve the numerical singularity problem, and the non-singular slip (NSS) calculation method is proposed. The proposed NSS method is applied to tire model performance test (TMPT) simulations to validate its performance.     

Transport effects of e-commerce: what can be learned after years of research?

This paper offers an extensive review of conceptual and quantitative studies on the implications of business-to-consumer (b2c) e-commerce on mobility. To create a more comprehensive understanding of the mobility implications we also discuss the complementary side: freight transport. Most studies conducted thus far have looked at the consequences of b2c e-commerce for either personal travel or goods movement, but not for both. The added value of this review article is that it not only explores the conclusions drawn in the wide-ranging published research, but also attempts to review the sampling strategies, definitions, assumptions and methodologies that lead to the diverse conclusions. For example, the paper discusses the differences in how “e-shopping” is defined (whether it includes browsing or only purchasing) and with what frequency a respondent e-shops (however it is defined) in order to be considered an “e-shopper”. The review describes how product differentiation is necessary to scrutinize the mobility effects of e-commerce. It points to studies which tend to have a dual conclusion. We try to observe whether complementary effects are given the same level of attention as substitution effects. Each of these factors can have sizable impacts on the quantitative conclusions reached. Our aim is that, by calling attention to these issues, the conclusions of studies will be discussed in a rigorous way to improve our knowledge of the transportation impacts of online shopping.     

A framework for urban freight policy analysis

This paper provides an overview of the urban freight process, in the context of the supply and demand aspects of freight. A framework for analysis is developed, and within that framework, particular aspects of the urban freight process are described. Issues of concern from a public policy viewpoint are highlighted.

Seven main instruments related to public policy are introduced and their application described — taxes and subsidies, regulations, investment, operational instruments, planning, public ownership and research.

It is concluded that the importance of urban freight to the community and its relevance to urban transport justifies a higher level of attention in transport planning and policy formulation, and that there are a wide range of policy instruments available to enable this to be done. The objective of such planning and policy making needs to be specified in each specific context.     

Assessing the impact of the built environment on travel behavior: a case study of Buffalo,New York

Assessing the impact of characteristics of the built environment on travel behavior can yield valuable tools for land use and transportation planning. Of particular interest are planning models that can estimate the effects of ‘smart growth’ planning. In this paper, a post-processor method of quantifying and searching for relationships among many aspects of travel behavior and the built environment is developed and applied to the Buffalo, NY area. A wide scope of travel behavior is examined, and over 50 variables, many of which are based on high-detail data sources, are examined for potentially quantifying the built environment. Linear modeling is then used to relate travel behavior and the built environment, and the resulting models may be applied in a post-processor fashion to travel models to provide some measure of sensitivity to built environment modifications. The study’s findings demonstrate that mode choice is highly correlated to measures of the built environment, and that many of the principles of smart growth appear to be a valid way to encourage non-vehicle travel. Home-based VHT and VMT appear to be affected by the built environment to a lesser degree.     

Identifying variations and co-variations in discrete choice models

This study introduces an extended version of a standard multilevel cross-classified logit model which takes co-variations into account, i.e., variations jointly caused by two or more unobserved factors. Whilst focusing on mode choice behavior, this study deals with four different types of variation: spatial variations, inter-individual variations, intra-individual variations and co-variations between inter-individual and spatial variations. Such co-variations represent individual-specific spatial effects, reflecting different responses to the same space among individuals, which may for example be due to differences in their spatial perceptions. In our empirical analysis, we use data from Mobidrive (a continuous six-week travel survey) to clarify the existence of co-variation effects by comparing two models with and without co-variation terms. The results of this analysis indicate that co-variations certainly exist, especially for utility differences in bicycle and public transport use in comparison with car use. We then sequentially introduce four further sets of explanatory variables, examine the sources of behavioral variations and determine what types of influential factors are dominant in mode choice behavior.