Network-wide traffic and environmental impacts of acceleration and deceleration among Eco-Driving Vehicles in different road configurations

Eco-Driving, a driver behaviour-based method, has featured in a number of national policy documents as part of CO₂ emission reduction or climate change strategies. This investigation comprises a detailed assessment of acceleration and deceleration in Eco-Driving Vehicles at different penetration levels in the vehicle fleet, under varying traffic composition and volume. The impacts of Eco-Driving on network-wide traffic and environmental performance at a number of speed-restricted road networks (30?km/h) is quantified using microsimulation. The results show that increasing levels of Eco-Driving in certain road networks result in significant environmental and traffic congestion detriments at the road network level in the presence of heavy traffic. Increases in CO₂ emissions of up to 18% were found. However, with the addition of vehicle-to-vehicle or vehicle-to-infrastructure communication technology which facilitates dynamic driving control on speed and acceleration/deceleration in vehicles, improvements in CO₂ emissions and traffic congestion are possible using Eco-Driving.     

A rational analysis of intact stability hazards involving small inland passenger ferries in Bangladesh

The safety of inland passenger vessels operating in Bangladesh has been investigated. By thorough analysis of past accident data, the main causes of intact stability failures have been determined: adverse weather conditions and overloading, likely resulting in crowding to one side. Historical series of wind data were gathered and their analysis suggests that an increase in the wind speed presently used in the Weather Criterion in force in Bangladesh could be advisable. A model of a small passenger ship typically operated in Bangladesh has been analyzed in order to identify the most relevant hazards under intact ship conditions. A strongly jeopardizing effect of overloading under intact ship conditions has been detected when analyzing the hazard from the crowding of people to one side.     

Trip misreporting forecast using count data model in a GPS enhanced travel survey

As Global Positioning System (GPS) technology advances, it has been increasingly used to supplement traditional self-reported travel surveys due to its promising features in capturing travel data with better accuracy and reliability. Realizing the limitations of diary-based surveys, this paper presents a study that directly accounts for trip misreporting behavior in trip generation models. Travel data were obtained from prompted-recall assisted GPS survey along with a diary-based survey. Negative Binomial models for count data were developed to accommodate misreporting behavior by introducing interaction effects of the sample-indicator variable with various personal and household variables. The interaction effects indicate how the impacts of the socioeconomic and demographic variables on trip-making vary across the two samples. Assuming that the GPS sample represents the ground truth, the interaction effects actually capture the likelihood and the extent of trip misreporting by detailed personal and household characteristics. The model results reveal significant interaction effects of several personal and household variables, indicating misreporting behavior associated with these attributes. The addition of interaction coefficients to the main effect model represents the real impacts of the independent variables, after compensating for trip misreporting behavior, if any.     

Modelling the dynamics between tour-based mode choices and tour-timing choices in daily activity scheduling

Transportation - The paper presents a dynamic discrete–continuous modelling approach to capture individuals’ tour-based mode choices and continuous time expenditure choices tradeoffs in...     

Determinants of certified motorcycle helmet use among postal delivery riders at rural areas in Peninsular Malaysia

This study aims to identify the determinants of certified helmet use among postal delivery riders (PDRs) in rural areas of Peninsular Malaysia. A cross-sectional study was done among 269 PDRs from 50 postal distribution centres (DC) nationwide. Data collection was achieved through observation of the helmets and a questionnaire. The quality of the motorcycle helmets was determined by the presence of the certification label issued by the Standards and Industrial Research Institute of Malaysia (SIRIM). The response rate was 99.3%. The odds of full-shell helmets having the SIRIM label were 37.1 times more than that of the half-shell helmets. The odds of non-purchased helmets having the SIRIM label were 14.9 times more than that of the purchased helmets. The odds of expensive helmets having the SIRIM label were 4.4 times more than that for cheaper motorcycle helmets. The odds of helmets owned by riders without a previous crash history having the SIRIM label were 1.9 times more than helmets owned by riders with a crash history. Full-shell helmets with SIRIM standard certification, non-purchased helmets, helmet price of US$11.00 or more, and motorcycle riders without any previous crash history were determinants that contributed towards the use of a certified motorcycle helmet. Multiple logistic regression indicated that two variables significantly predicted the use of a certified motorcycle helmet among PDRs – helmet type and cost. An employer that provides the employees with full-shell motorcycle helmets with SIRIM standard certification label that costs at least US$11.00 and hiring motorcycle riders without any previous crash history gives a higher chance of compliance with standard certified motorcycle helmet usage.     

Logistics and supply chain management

In this paper an introduction to the principles and methods used in logistics and supply chain management is presented. It begins by a discussion on fundamentals and explains the relevant terms. Next policy and practice associated with logistics and freight services are regarded with a focus on the EU policy for the sector which greatly influences the development of logistics chains and services. Mathematical formulation of typical transport and logistics-related problems is also presented followed by a discussion on the concept of sustainability.     

Strength and deformability of corroded steel plates under quasi-static tensile load

The objective of this study was to estimate the strength and deformability of corroded steel plates under quasi-static uniaxial tension. In order to accurately simulate this problem, we first estimated the true stress–strain relationship of a flat steel plate by introducing a vision sensor system to the deformation measurements in tensile tests. The measured true stress–stain relationship was then applied to a series of nonlinear implicit three-dimensional finite element analyses using commercial code LS-DYNA. The strength and deformability of steel plates with various pit sizes, degrees of pitting intensity, and general corrosion were estimated both experimentally and numerically. The failure strain in relation to the finite element mesh size used in the analyses was clarified. Two different steels having yield ratios of 0.657 and 0.841 were prepared to examine the material effects on corrosion damage. The strength and deformability did not show a clear dependence on the yield ratios of the present two materials, whereas a clear dependence was shown with respect to the surface configuration such as the minimum cross-sectional area of the specimens, the maximum depth of the pit cusp from the mean corrosion diminution level, and pitting patterns. Empirical formulae for the reduction of deformability and the reduction of energy absorption of pitted plates were proposed which may be useful in strength assessment when examining the structural integrity of aged corroded structures.     

Weekly activity-travel behaviour in rural Northern Ireland: differences by context and socio-demographic

Despite a wide variation in access to goods and services between rural areas, common policy interventions are often proposed in Northern Ireland. Questions remain as to the level and form of policy differentiation that is required, if any, both within and between different rural areas. This issue is investigated in this paper through the analysis of activity-travel patterns of individuals living in two rural areas with different levels of area accessibility and area mobility. Three focus groups, 299 questionnaires and 89 activity-travel diaries for 7 days were collected for individuals from these areas. Regression analyses were employed to explore the degree to which different factors influence activity-travel behaviour. The results indicate that individuals from rural areas with a higher level of accessibility are more integrated within their local community and as a result, are potentially less at risk of being excluded from society due to immobility. Differences, however, were also found between different groups within an area (e.g. non-car owning individuals who were more reliant on walking, and low-income individuals who made trips of a shorter distance). Based on the study findings and a review of existing policies, this research highlights the need to tailor policy responses to reflect the particular sets of circumstances exhibited in different areas.     

Exploring built environment impacts on transit use – an updated meta-analysis

ABSTRACT

The built environment (BE) is widely accepted to influence transit use (TU). Evidence to date suggests the relationship is dependent on many factors which can be difficult to account for in quantitative studies. This creates barriers to transferring research into practice. Considering many studies together can be useful for accounting for more of the factors impacting transit use. Yet, meta-analysis of research measuring these influences was last undertaken in 2010 based on 18 studies. Since then 90 new quantitative studies have been published. These recent studies use improved methodologies and are conducted in more diverse geographies. This paper reports an improved and updated meta-analysis of built environment impacts on transit use. It compares elasticity estimates from research published pre-and post-2010 and explores the impact of new methods and a more diverse geographical representation on findings. Updated meta-elasticities range from <0.01 to 0.26; a similar range to the 2010 study. However, at the individual indicator levels, more recent results are different. Elasticities for urban density, including population, employment and commercial density, have increased significantly in studies published since 2010, as did that of land use mix. However, measures of local access, design and jobs-housing balance decreased in post-2010 studies. These results confirm the small but imprecise relationship between the BE and TU. Results also suggest that while the range of elasticity impacts is relatively consistent, new study methodologies, notably those that control for regional accessibility and self-selection, and the increasing geographical diversity in study applications, is acting to change BE-TU findings at the indicator level. Research setting and context are important to consider when using empirical results to design BE strategies to promote transit use.     

Changing household car ownership level and life cycle events: an action in anticipation or an action on occurrence

This paper analyzes households’ decision to change their car ownership level in response to actions/decisions regarding mobility issues and other household events. Following recent literature on the importance of critical events for mobility decisions, it focuses on the relationship between specific events (e.g. childbirth and buying an extra car), rather than trying to explain the status of car ownership from a set of stationary explanatory variables. In particular, it is hypothesized that changes in household car ownership level take place in response to stressors, resulting from changed household needs or aspirations. The study includes a broad range of events. Apart from changes in work status, employer and residential location, it analyzes demographic events such as household formation and childbirth. Also, it scrutinizes the temporal sequence in which chains of related events are most likely to occur. To this end, data from a retrospective survey that records respondents’ car ownership status, as well as residential and household situation over the past 20 years are used. A panel analysis has been carried out to disentangle typical relationships. The results suggest that strong and simultaneous relationships exist between car ownership changes and household formation and dissolution processes. Childbirth and residential relocation invoke car ownership changes. Changes are also made in anticipation of future events such as employer change and childbirth. Childbirth is associated with increasing the number of cars, whereas the effect of employer change goes the opposite way. Job change increases the probability of car ownership change in the following year.