Dynamic traffic assignment (DTA) has received increasing attention in recent years, and there are numerous examples of practical implementations. This work adds to the literature by describing the ongoing experience of building the first large-scale simulation-based DTA model in Australia. The input data for the model are summarized, and an in-depth discussion and an analysis of model output and the calibration process are presented. Current results put 80% of the 322 calibration points spread across the network within an acceptable bound of error, but the project found that alternative metrics of network performance also must be considered so that other aspects of model realism are not neglected. The described DTA model could be used for evaluating important policy decisions and infrastructural development in the context of the macro- and mesoscale network operation. Additionally, this project is a proof of concept for the Australian region and may provide insight to practitioners interested in emerging areas of transport planning and traffic modeling.
Obesity and other chronic diseases are becoming more prevalent in affluent countries such as Australia. Researchers are trying to understand and combat this trend. One related growing stream of research explores the role of the built environment and transport system on an individual’s weight. However, results from many studies conducted have been contradictory. A primary cause of these contradictions is due to how neighborhood areas are defined, which directly affects how the built environment variables are calculated in geographic information systems. The potential impacts on regression analysis resulting from different data aggregation methods are well documented in spatial studies, geography, and regional planning fields, and the problem is primarily referred to as the modifiable aerial unit problem. In this paper, the focus is on reducing the error caused by the modifiable aerial unit problem by introducing a new data aggregation method. Individual health and lifestyle data are obtained from the survey of households, income, and labor dynamics in Australia, and the relationship between the built environment and obesity is evaluated by using a discrete choice model. The proposed aggregation method is evaluated across three spatial scales and compared against a conventional data aggregation method (i.e., using predefined administrative boundaries such as census tracts). The results reveal a stronger relationship between land use variables and obesity when the proposed aggregation method is implemented. This paper is relevant primarily to researchers because it provides an improved aggregation method to deal with some privacy restrictions of surveys. It is also relevant to practitioners and policy makers by its quantification of the association between specific built environment variables and obesity.
Ramp metering is a control technology used to manage the flow of traffic entering motorways and freeways, with the primary aim of minimizing congestion on the main thoroughfare. This technique has been studied and implemented globally since the 1960s. It has been shown that ramp meters improve the overall efficiency of the system; however, the distribution of the benefits and costs across users has been questioned, and this is one of the main constraints on user acceptance of the ramp metering system. The typical methodology used in the literature is to assume that the most equitable condition is when all on-ramps have the same delay across space or time. This research developed a new definition of horizontal equity for ramp meters and a proposed method for calculating it. A hypothetical microsimulation model was developed on the basis of a motorway in Sydney, Australia, and used as the platform to demonstrate how the proposed equity definition can be evaluated. To assist in the interpretation, two configurations of a ramp metering algorithm were simulated and compared. Finally, the typical equality measure used in the literature was calculated for the same scenarios and compared with the proposed equity measure. The results showed that these two measures can favor scenarios. A qualitative discussion of the expected benefits of the proposed equity measure is offered. Those expected benefits are an easy-tocommunicate means of justifying the metering rates for user acceptance (rates that are arguably fairer, compared with the typical equality measure); a measure that is complementary to integration with other intelligent transportation system technology such as tolled bypass lanes; and ease of incorporation in the long-term traffic management plan.Equity, as a representation of justice or fairness, refers to the distribution of impacts (benefits and costs) and whether that distribution is considered appropriate. Road authorities consider these distributions as part of the evaluation process of transport projects and as essential for the support of public officials and the general public (1-4). How equity is defined and measured can significantly affect analysis results.There are three fundamental classifications of equity: (a) equality or egalitarian, where each person is assigned the same amount of benefit; (b) horizontal equity (also called market equity), which relies on the idea that you should get what you pay for-thus, benefits and costs are distributed on the basis of the amount of benefits and costs that are received from the individual; and (c) vertical equity, where benefits are distributed on the basis of the needs or socioeconomic status of the individual. However, when evaluating the equity of a system, many other aspects also must be considered, including the measure of benefits and costs, the aggregation method to obtain measurements, the categories of people, the definition of the base case, and the formulation used to summarize the distribution (5).Ramp meters (RMs) have been in use for more than 5...
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