Long-term behavior of particulate matters at urban roadside and background locations in Seoul,Korea

The concentrations of particulate matter, PM_2.5, PM₁₀, and TSP at an urban roadside and an urban background station are analyzed. Data collected over a 10 year period are analyzed. The concentrations of the particulates measured at the urban site are systematically larger than at the background station. The mean PM values at the former also exhibit a slight fall over the decade unlike those at the background station. Overall, the particulate matters at both locations are in an intermediate range of global level, e.g., approximately two times lower than those in other Asian regions but higher than in Europe.     

Decision support for simulating the car park activity in an urban area

Complexity of car park activity is reproduced from a concurrent execution of behaviour of various drivers. This paper presents a step in the development of a multimodal traffic simulator based on multi‐agent paradigm and designed as a decision aid tool as well as a video game. The user‐player has the opportunity to test different scenarios. We propose an approach for designing the decision‐making rules and the learning mechanism for a car driver agent. For that, a panel of methods such as stated preference modelling, Design Of Experiments and data fusion is used. Initial behavioural models, based on similar preferences, are developed for specified categories. Each agent will adapt its behaviour after executing its learning process. Our approach can be used in order to optimize needs of road network users and those of people in charge of traffic regulation. A demonstrator has been developed to test parking policies in an urban area as well as changes of car park characteristics.     

A review of Australian traffic system design models

The demands for traffic infrastructure are increasing. Yet over the last decade investment in new infrastructure has decreased at all levels. Traffic systems designers are, therefore, being asked to be more accurate in their prediction of the impacts of changes, to analyse ever more complex situations and to extract more from the existing traffic system. This paper reviews developments in techniques for analysing the impacts of changes in the traffic system. It looks at intersection, route, network, parking lot and public transport design models that have been developed in Australia. Particular emphasis is given to the considerable developments in microcomputers and graphics and the impact these are having on the models. Future developments are also discussed.     

Parking restraint policy and urban vitality

The aim of the paper is to examine whether parking restraint policies may have impacts on the economic vitality of urban centres. Literature from empirical, attitudinal and modelling studies is reviewed within a structure based around a conceptual framework of parking impacts. The search for relevant material was undertaken both for the UK and overseas, but the discussion and conclusions were related to the UK context. Original modelling was undertaken and is reported here. This review found that as parking restraint policies have not been previously implemented with consistency or longevity, there is a lack of direct evidence, given that land-use impacts typically involve a long-term response. Furthermore, different methods of examining impacts have come to very different conclusions. Attitudinal evidence suggests that there is a high level of sensitivity to parking provision, whereas aggregate statistical studies tend to find only a weak relationship. The reasons underlying these differences are discussed. Land-use/transport models show impacts if there is sufficient change in generalized cost, although the spatial distribution of impacts, and impacts by household or employment disaggregation, vary considerably. Given the inconclusive nature of the evidence to date, only tentative policy implications can be drawn. Recommendations for further research are outlined, both for empirical study and for model enhancements.     

Issue Definition and Planning for Whalewatching Management Strategies in Ensenada,Mexico

The exceptional growth of whalewatching in Baja California Sur (BCS) and other parts of Mexico during the last 10 years motivated the design and implementation of a Mexican whalewatching law based on experiences in BCS. However, recent research in the Ensenada whalewatching area confirms that this law is insufficient in this area because whalewatching boats and other fishing, cruising, or drifting boats influence the behavior (swimming direction and velocity) of migrating gray whales. In the long term, the migration corridor might be displaced offshore, and whalewatching may become infeasible. This study proposes a management planning process to adapt regulations to this area, to promote adherence to regulations by encouraging self-regulation and strengthening law enforcement, and to enhance the tourist service on board. The actors involved were identified.     

Stated preference analysis of travel choices: the state of practice

Stated preference (SP) methods are widely used in travel behaviour research and practice to identify behavioural responses to choice situations which are not revealed in the market, and where the attribute levels offered by existing choices are modified to such an extent that the reliability of revealed preference models as predictors of response is brought into question. This paper reviews recent developments in the application of SP models which add to their growing relevance in demand modelling and prediction. The main themes addressed include a comparative assessment of choice models and preference models, the importance of scaling when pooling different types of data, especially the appeal of SP data as an enriching strategy in the context of revealed preference models, hierarchical designs when the number of attributes make single experiments too complex for the respondent, and ways of accommodating dynamics (i.e. serial correlation and state dependence) in SP modelling.An earlier modified version was presented as the keynote address to the 1993 National Conference on Tourism Research, held at the University of Sydney, 19 March 1993. The comments of Jordan Louviere, Lester Johnson, Paul Hooper, W.G. Waters II and Mark Bradley are appreciated.     

Generating complete all-day activity plans with genetic algorithms

Activity-based demand generation contructs complete all-day activity plans for each member of a population, and derives transportation demand from the fact that consecutive activities at different locations need to be connected by travel. Besides many other advantages, activity-based demand generation also fits well into the paradigm of multi-agent simulation, where each traveler is kept as an individual throughout the whole modeling process. In this paper, we present a new approach to the problem, which uses genetic algorithms (GA). Our GA keeps, for each member of the population, several instances of possible all-day activity plans in memory. Those plans are modified by mutation and crossover, while bad instances are eventually discarded. Any GA needs a fitness function to evaluate the performance of each instance. For all-day activity plans, it makes sense to use a utility function to obtain such a fitness. In consequence, a significant part of the paper is spent discussing such a utility function. In addition, the paper shows the performance of the algorithm to a few selected problems, including very busy and rather non-busy days.     

The rational locator reexamined: Are travel times still stable?

The rational locator hypothesis posits that individuals can, if they choose, maintain approximately steady journey-to-work travel times by adjusting their home and workplace. This hypothesis was coupled with the observation of long-term stability in drive alone journey-to-work times in metropolitan Washington (those times were unchanged from 1957 through 1968 to 1988). Despite the increase of average commuting distance and congestion, trip duration remained constant or even declined when controlling for travel purpose and travel mode because of shifting a share of traffic from slow urban routes to faster suburban routes. This observation has significance, as it is important to know for travel demand analysis if there is an underlying budget, or even a regularity, as this helps us determine whether our forecasts are reasonable. To re-test the underlying rationale for the hypothesis that travel times are stable, intra-metropolitan comparisons of travel times are made using Washington DC data from 1968, 1988, and 1994, and Twin Cities data from 1990 and 2000. The results depend upon geography. For the larger Washington DC region, keeping the same geography shows little change in commute times, but using the larger 1994 area suggests an increase in commute times. However, the Twin Cities, starting from a much shorter commute time, shows a marked increase over the decade, using either the smaller or the larger geography. Despite the remarkable continuing observation of stability in drive alone commuting times in metropolitan Washington, we reject the theory of personal commuting budgets, as we find that not only are commuting times not generally stable over time at the intra-metropolitan area, but that commuting time clearly depends on metropolitan spatial structure.     

Toward the betterment of risk allocation: Investigating risk perceptions of Australian stakeholder groups to public-private-partnership tollroad projects

This paper presents a qualitative assessment of the risk perceptions held by key Australian stakeholder groups in the context of tollroads operated under the public-private-partnership model. The findings confirm that experience accumulated in recent years has contributed toward the betterment of risk-sharing optimisation amongst the contracting parties. The knowledge acquired through in-depth interviews supports the common view that equitable risk sharing is the vital ingredient of value for money. The proposition that the private sector is better equipped to manage commercial risks involving economic decision making whilst risks that have embedded unquantifiable social and public values and those in the domain of public governance are best left with government alone, appears to be replete with refutable implications. Public perception is a malleable concept and should be managed by both sectors.     

Incompleteness and clarity in bus contracts: Identifying the nature of the ex ante and ex post perceptual divide

In the transport sector, many types of contracts exist. Some are very precise, and strive for completeness; others are very ‘light-weight’ and are incomplete. Bus and coach contracts, won through competitive tendering or negotiation, are typically incomplete in the sense of an inability to verify all the relevant obligations, as articulated through a set of deliverables. This paper draws on recent experiences in contract negotiation, and subsequent commitment in the bus sector, to identify what elements of the contracting regime have exposed ambiguity and significant gaps in what the principal expected, and what the agent believed they were obliged to deliver. We develop a series of regression models to investigate the extent of discrepancy between the principal and the agents perceived ‘understanding’ of contract obligations. The empirical evidence, from a sample of bus operators, is used to identify the extent of perceived incompleteness and clarity across a sample of bus contracts. A noteworthy finding is the important role that a trusting partnership plays in reducing the barriers to establishing greater clarity of contract specification and obligations, and in recognition of the degree of contract completeness.