Explaining the “immigrant effect” on auto use: the influences of neighborhoods and preferences

Since immigrants will account for most urban growth in the United States for the foreseeable future, better understanding their travel patterns is a critical task for transportation and land use planners. Immigrants initially travel in personal vehicles far less than the US-born, even when controlling for demographics, but their reliance on autos increases the longer they live in the US. Cultural or habitual differences, followed by assimilation to auto use, could partly explain this pattern; and it may also be partly due to changes in locations and characteristics of home and work neighborhoods. Previous studies have rarely investigated non-work travel, and have not tested workplace land use measures, compared the relative influences of enclave and home neighborhood measures, or looked at the role of culturally-bound residential preferences or motivations for migration. This study relies on a unique and rich dataset consisting of a survey of US residents born in South Asia, Latin America, and the US, joined to spatial information in a GIS. I find that the home built environment is the most consistently influential factor in explaining the lower auto use of both recent and settled Latin American immigrants. Indian immigrants use autos less than would be expected given their home and work neighborhoods. There is little evidence that either ethnic enclaves, or cultural differences, play a role in lower auto use by immigrants. These results suggest there may be a role for neighborhood built environment policies in delaying immigrant assimilation to auto use in the US.     

The impact of port operations on efficient ship operation from both economic and environmental perspectives

Recently, shipping lines have focused on efficient ship operation, which relates to energy efficiency issues in shipping and, particularly, to operational issues such that the minimisation of fuel consumption and resulting greenhouse gas emissions. Efficient ship operation in container lines is closely related to the ship’s time at sea and ship’s time in port. Reduction in port time, thanks to high-quality port operations, allows improvement in the operational efficiency of a liner service by reducing the fuel consumption of a ship at sea and its resulting CO₂ emissions. The main goal of this article is to investigate how time in port affects efficient ship operation in terms of operating costs, CO₂ emissions and externalities. For this, as a methodology, a simulation based upon system dynamics is introduced. Major finding is that less time in port resulting from the improvement of port operations contributes to efficient ship operation in terms of operating costs, amount of CO₂ emissions and external effects in the liner shipping industry. In particular, a sensitivity analysis on efficient ship operation vis-à-vis the quality of port operation shows that bigger ships need to select highly productive calling ports that provide less time in port.     

Bridging the gap between complex data and decision-makers: an example of an innovative interactive tool

Abstract

The increasing capacity of technological tools, as well as the advent of geographic information systems, has multiplied the ability to process large sets of microdata. At the same time, modeling concerns and the quest for a more in-depth understanding of individual behaviors is requiring more, and better, data. The gap between scientific modeling and informational tools for decision-making seems to be widening.

In the Greater Montreal area, large sets of microdata have been available for more than 30 years. Along with the development of modeling and planning tools, particular attention has been given to the continuous enlightening of planners and decision-makers with respect to the outcomes of the various surveys. This has led to the development of particular interactive tools, specifically addressed at local planners, which present the most significant information regarding travel and demography, for geopolitically relevant areas.

This paper presents the most recent interactive tool that has been developed for local planners in the Montreal area. It integrates information from both the most recent travel survey held in the region and the Canadian census. It offers both ease of use and relevant analytical means to assist in exploring the complex relations between spatial locations, demographic features, and activity-travel indicators.     

The spatial dimensions of immobility in France

In travel surveys, immobility is often approached as a technical issue that needs to be dealt with in order to measure mobility more accurately. By covering mobility patterns over a full week, the 2008 French Travel Survey allows immobility to be analysed other than as a marginal and random phenomenon. For working days alone, 28.8% of the adults in the survey had experienced one or more immobility episodes. By considering the intensity of immobility, and by introducing latent variables into Structural Equation Modelling, we have been able to propose a model with reasonable explanatory power. Our findings agree with previous studies and also show that within suburban or rural areas, access to shops or the type of local residential fabric are also factors that influence the number of immobile days. In addition, our findings show that the effects of the determinants differ between categories of individuals, notably between working adults and students on the one hand, and between retired and non-working people on the other.     

KERFIX, a time-series station in the Southern Ocean: a presentation

Between January 1990 and March 1995, the research project KERFIX undertook the first regular noncoastal multiyear acquisition of parameters related to the carbon cycle in the Southern Ocean at a time series station located at 50°40′ S–68°25′ E, 60 miles southwest of the Kerguelen Islands. The objectives of KERFIX are (1) to monitor the ocean/atmosphere CO₂ and O₂ exchanges and to understand which processes govern these exchanges (2) to observe and interpret the seasonal and interannual variability of the production, flux, decomposition and dissolution of carbon and associated elements at this location. In addition, micropaleontological studies describe the present and past flux dynamics in this oceanic area, to improve the knowledge of the transfer functions of some oceanographic proxies. This paper presents a survey of the KERFIX program: scientific objectives, organization of the field operations and some main results obtained since the beginning of KERFIX program, as well as the results of the temporal evolution of hydrological, chemical and biological parameters.     

Inter-firm relationships and shipping services: the case of car carriers and automobile importers to the United States

This paper is an initial exploration of inter-industry relationships and linkages in the context of automobile imports to the United States. It is our contention that the nature and structure of the engagement between automobile importers and shipping lines is central to understanding the evolution of the car carrier trade. Building on the literature on transactions costs, and supply and value chains, we show that the regimes currently governing car carriage services range from markets to vertical integration via network forms of engagement. We illustrate this through a detailed discussion of Japanese inter-firm networks and an examination of automobile import data to the US from 1980 to 2000. The findings raise important questions for future research on the impact of inter-industry relationships in various strategic decisions of steamship lines, shippers and port authorities including port entry, port choice and routeing, technological and investment choices, and trajectories of supply chain development.     

Approaches to the future in U.S. urban transportation planning

In appreciation of the fact that longer-run considerations are particularly important in the development of urban transportation, during the past three decades American transportation planning has been employing increasingly sophisticated approaches to the future. This article discusses four phases in this evolution, with a given focus dominant in each period.During the first period, following on the initial provision of federal government funds for the construction of highways in and around cities, major reliance was based on simple projections of travel demand in metropolitan regions, based mainly on current patterns.This was followed by an approach which focused on an analysis of impacts on transportation systems of projected land uses, based on forecasts of population and economic growth for a target year, on the assumption that facilities were to be provided to move all vehicles that wanted to move from here to there at least possible cost.The third period was characterized by an increasing consciousness of the value of articulating national and local goals in making transportation decisions, going beyond narrow economic and mobility objectives, and including the notion of trade-offs among goals.The most recent period discussed is one characterized by rising interest in futures studies, using methods such as Delphi and cross-impact analysis and approaches such as alternative futures, as well as a search for achieving flexibility in transportation development and for means of limiting resource commitment in the face of the uncertainties of the future (keeping options open).It is pointed out that we still have a long way to go in learning how to evolve feasible images of the future, with associated explicit urban life-style goals, that come to grips with societal variety and conflicting interests.     

Land requirements for public transport facilities in urban areas—A statistical approach

The major aim of this work is to develop a primary tool for the quantitative determination of land areas needed to fulfil the diverse functions of public transport. The need for such a tool is obvious; worldwide there is a lack of criteria for determining the types of areas needed, their size, and relative location in the urban system. Moreover, there is a lack of awareness regarding land allocation during the various planning stages, both by urban planners and decision makers. This work attempts to identify various types of facilities to be allocated within the urban framework, and to determine quantitative guidelines for the land needed for them. A statistical analysis is performed in order (i) to identify major transit facilities and operational data functions for which land must be allocated, and (ii) to forecast areas for types of facilities not dealt with by the statistical analysis. The statistical forecast is based on fitting a regression model to the input data. The outcome of this work is presented in terms of three statistical relationships and an indirect relationship: between socio-economic and demographic variables (independent) to the dependent variables, either operating variables or land area variables, and between operating variables (independent) and land area variables (dependent), where for the latter there is also an indirect relationship while using standards.     

The influence of suspension components friction on race car vertical dynamics

This work analyses the effect of friction in suspension components on a race car vertical dynamics. It is a matter of fact that race cars aim at maximising their performance, focusing the attention mostly on aerodynamics and suspension tuning: suspension vertical and rolling stiffness and damping are parameters to be taken into account for an optimal setup. Furthermore, friction in suspension components must not be ignored. After a test session carried out with a F4 on a Four Poster rig, friction was detected on the front suspension. The real data gathered allow the validation of an analytical model with friction, confirming that its influence is relevant for low frequency values closed to the car pitch natural frequency. Finally, some setup proposals are presented to describe what should be done on actual race cars in order to correct vehicle behaviour when friction occurs.     

Enhancing roll stability of heavy vehicle by LQR active anti-roll bar control using electronic servo-valve hydraulic actuators

Rollover of heavy vehicle is an important road safety problem world-wide. Although rollovers are relatively rare events, they are usually deadly accidents when they occur. The roll stability loss is the main cause of rollover accidents in which heavy vehicles are involved. In order to improve the roll stability, most of modern heavy vehicles are equipped with passive anti-roll bars to reduce roll motion during cornering or riding on uneven roads. However these may be not sufficient to overcome critical situations. This paper introduces the active anti-roll bars made of four electronic servo-valve hydraulic actuators, which are modelled and integrated in a yaw-roll model of a single unit heavy vehicle. The control signal is the current entering the electronic servo-valve and the output is the force generated by the hydraulic actuator. The active control design is achieved solving a linear optimal control problem based on the linear quadratic regulator (LQR) approach. A comparison of several LQR controllers is provided to allow for tackling the considered multi-objective problems. Simulation results in frequency and time domains show that the use of two active anti-roll bars (front and rear axles) drastically improves the roll stability of the single unit heavy vehicle compared with the passive anti-roll bar.