Modelling the effects of physical–biological interactions and spatial variability in spawning and nursery areas on transport and retention of sardine Sardinops sagax eggs and larvae in the southern Benguela ecosystem

A particle-tracking individual-based model (IBM) coupled with a 3-D hydrodynamic model was used to investigate how spatial variability in spawning and nursery grounds may influence transport and retention of sardine (Sardinops sagax) eggs and larvae in the southern Benguela ecosystem. A temperature-dependent Bělehrádek development model based on laboratory growth data was used to determine the duration of one egg and two larval stages. Successful transport/retention depended on each particle's stage of development rather than its age. Results show that recruitment could occur in two distinct nursery areas on the west and south coasts of South Africa. Three viable recruitment ‘systems’ were identified: two are retention-based (spawned and retained on the west coast (WC–WC) or the south coast (SC–SC)) and one is transport-based (spawned on the south coast and transported to the west coast (SC–WC)). In the WC–WC system, the vertical distribution of eggs influenced retention; at intermediate depths of spawning (25–50 m) eggs avoided both offshore Ekman drift and deep cold water. In the SC–SC system, the area of spawning was important; > 50% of eggs from the eastern Agulhas Bank (EAB) were retained in the south coast nursery grounds, whereas very few eggs were transported there from west of Cape Agulhas. In the SC–WC system, area of spawning was also important; 40% of the eggs spawned on the western Agulhas Bank (WAB) were transported to the west coast nursery ground. Sardine life history strategy could be divided between two main systems: the west coast system (spawning on the WAB and WC, and recruiting to the WC) and the Agulhas Bank system (spawning on the central and eastern Agulhas Bank, and recruiting to the SC).     

Shift of reference point and implications on behavioral reaction to gains and losses

It is widely recognized that individual decision-making is subject to the evaluation of gains and losses around a reference point. The estimation of discrete choice models increasingly use data from stated choice experiments which are pivoted around a reference alternative. However, to date, the specification of a reference alternative in transport studies has been fixed, whereas it is common to observe individuals adjusting their preferences according to a change in their reference point. This paper focuses on individual reactions, in a freight choice context, to a negative change in the reference alternative values, identifying the behavioural implications in terms of loss aversion and diminishing sensitivity. The results show a significant adjustment in the valuation of gains and losses around a shifted reference alternative. In particular, we find an average increase in loss aversion for cost and time attributes, and a substantial decrease for punctuality. These findings are translated to significant differences in the willingness to pay and willingness to accept measures, providing supporting evidence of respondents’ behavioural reaction.     

A KBS application for market research advice in transport

This paper presents some results of a knowledge based system (KBS) development applied to market research (MR) issues in transport. This application represents a rule production approach to decisions associated with the definition of appropriate survey procedures for various operation‐management problems in a transport enterprise or agency. The basic idea is to provide an aid for the user (manager, student or practitioner), who is concerned with MR, but is not very familiar with this field or has some concerns over data‐gathering and the use of that information. It focuses on specific applications in the transport environment and gives the user some support in maintaining greater consistency in his (her) decisions.

The objective of this paper is to describe the system structure, to point out some important aspects and problems arising during its development and also to make some comments with respect to the further development of this and similar systems.     

Limitations of transport policy

There is an implication in the notion of 'transport policy' that substantial improvements could be made to the transport system given sufficient ingenuity, investment and good will. This paper argues that such policy aspirations cannot cope with the desire for ever-increasing mobility, a deep and powerful force in modern society. In densely populated countries there is no possibility of meeting the demand for unconstrained movement through construction of additional transport infrastructure, since new and longer journeys would quickly fill the extra capacity until the congestion equilibrium is re-established. What limits mobility in practice is the time individuals have available for travel, time which is equitably distributed. Transport plans need to acknowledge this time constraint as fundamental, and accordingly be realistically modest about what is achievable. It is an illusion that the transport system could be substantially more efficient whilst remaining equitable.     

Book reviews of Maritime Transport. Edited by M ary R. B rooks,K enneth B utton and P eter N ijkamp (Cheltenham UK: Edward Elgar, 2002) [Pp. 553] £150.00. ISBN 1 84064 552 0

Using the extended task-technology fit (TTF) model, this paper investigates how certain factors (e.g. task characteristics, technology (i.e. intranet) characteristics, middle managers’ demographic characteristics, task-technology fit, and perceived usefulness and usage) affect the port middle managers’ job performance. Numerous organizations in the port industry constitute the population of interest. The preliminary results suggest that the majority of middle managers believe that intranet could improve their job performance. The results from the structural equation modelling (SEM) indicate that task characteristics and intranet characteristics significantly justify their variance on task-technology fit. However, demographic variables do not predict task-technology fit. Perceived usefulness is found to be a predictor of intranet usage. Task technology fit, on the other hand, significantly predicts usage and explains the variance on middle managers’ job performance. This study is the first study to investigate the effects of intranet usage and managerial performances in an integrative perspective, taking into account various user acceptance models and users’ demographic characteristics.     

Psychological items: a useful addition in modeling travel behavior on managed lanes

Transportation - Managed lanes (MLs) are a tool to more efficiently operate segments of a freeway. As ML prevalence increases in the United States of America, it is important to understand travel...     

Discrete/continuous econometric models and their application to transport analysis

A wide range of transport‐related decisions involve the linking of discrete choices (e.g. of vehicle choice) and continuous choices (e.g. of vehicle use). In recent years econometricians have developed procedures for integrating such choices into a framework that is both economically and statistically sound. The literature is however somewhat technical. The objective of this paper is to provide a general overview of the basic elements of discrete/continuous econometric modelling with an emphasis on transport applications. It is hoped that such an introduction will demonstrate that the essence of the approach for the practitioner is quite straightforward and can be implemented with widely available computer software.     

Delivering Value for Money to Government through Efficient and Effective Public Transit Service Continuity: Some Thoughts

Abstract

This paper documents some thoughts on the reform agenda in public transit that is occurring throughout the world. The specific focus is on a growing commitment to competitive regulation through competitive tendering, and the efforts by a few governments (notably in Australia) to take control of the tangible assets used by private operators as a mechanism to exercise the opportunity, if so taken, to put services out to competitive tender. The paper reviews the theoretical arguments and empirical evidence on contracting regimes and asset ownership, and the role that government and the operator might play in a setting in which building trusting and collaborative partnerships has merit in delivering services that are in the main funded from the public purse.     

Applications of transport economics and imperfect competition

The great majority of analyses made in transport economics use, explicitly or, more often, implicitly, the common assumption of perfect competition. This is the case, for instance, when infrastructure projects are evaluated using the mere sum of the surpluses of transport users and providers. Even when putting aside the question of externalities such as noise, safety or environmental quality, the real chain of economic interactions that takes place in transport provision or downstream of transport provision is not taken into account. Surely enough, describing and simulating this chain could be quite complex. Nevertheless, it is not uninteresting to try to estimate if it does make a big difference or not to make this approximation. The paper makes such an attempt for two broad kinds of applications of transport economics:     

Forecasting automobile petrol demand in Australia: An evaluation of empirical models

Transport fuel consumption and its determinants have received a great deal of attention since the early 1970s. In the literature, different types of modelling methods have been used to estimate petrol demand, each having methodological strengths and weaknesses. This paper is motivated by an ongoing need to review the effectiveness of empirical fuel demand forecasting models, with a focus on theoretical as well as practical considerations in the model-building processes of different model forms. We consider a linear trend model, a quadratic trend model, an exponential trend model, a single exponential smoothing model, Holt’s linear model, Holt–Winters’ model, a partial adjustment model (PAM), and an autoregressive integrated moving average (ARIMA) model. More importantly, the study identifies the difference between forecasts and actual observations of petrol demand in order to identify forecasting accuracy. Given the identified best-forecasting model, Australia’s automobile petrol demand from 2007 through to 2020 is presented under the “business-as-usual” scenario.