John Taplin

Car trip attraction and route choice in Australia

Abstract The capacity of tourism destinations to attract visits and the propensity to make round trips to remote sites were approached through a model based on populations, travel times, traffic on road links, and identification of prime tourism destinations. A genetic algorithm was used to simultaneously estimate a gravity model of trip generation, incorporating an attraction population multiplier, and a route assignment model. Local residents and tourists were covered in separate but additive parts of the model. Results indicate an attraction multiplier of approximately four and a high propensity for long-distance car tourists to return home by a different route.

Preserving the symmetry of estimated commuter travel elasticities

Travel price and time elasticities are increasingly being derived from discrete choice models of the multinomial or nested logit form. These elasticities are then applied to obtain predictions of changes in travel demand consequent on a policy change in prices and travel times. The majority of the choice elasticities are estimated within the behavioural setting of modal choice, holding total travel fixed. A few mode choice models have recently relaxed the multinomial logit model assumption of equal variance in all the random components of the indirect utility function to permit unconstrained variances across all alternatives (subject to identification for one alternative). This enables the derivation of behaviourally meaningful and unique cross choice elasticities for each pair of alternatives. Under constant variance, only the direct choice elasticities have behavioural meaning. While this is an important advance in discrete choice modelling, the derivation of share elasticities is conditional on a fixed total demand, and the procedure cannot be relied on to carry through two important properties of the model into the demand elasticity matrix--namely symmetry and zero share weighted column sums. This paper takes a set of empirically derived choice elasticities and presents a second stage procedure to adjust these elasticities to arrive at an internally consistent matrix of demand elasticities. We draw on a recent data set collected in Sydney which utilises revealed preference and stated choice data to estimate a joint model of ticket choice conditional on mode and choice of mode for commuter travel.

A linear program to model daily car touring choices

Abstract A multi-period linear program is used to model daily decisions by Western Australian car tourists, subject to limits on average daily driving distance and the requirement that each journey starts and finishes at Perth within available vacation time. Varying weights or values are attached to going to multiple destinations and to warmer climates. Resulting choice patterns approximate to actual sequences of day-to-day choices by car tourists. A weighted sum of linear programming models provides a synthesized distribution of trips which is similar to trip patterns revealed by survey data. This offers an insight into the factors and constraints influencing tourist decisions.

Policy-sensitive selection and phasing of road investments with a goal program

A goal program to select and schedule road projects can include policy considerations in addition to those covered by cost-benefit evaluation. Five economic benefits and twelve environmental, developmental and accessibility objectives constitute the goals in a rural application in Western Australia. A plan and construction schedule can be generated for any set of priorities, each satisfying the budget constraint. Government can choose from them to match current policy concerns and meet the needs of affected residents. The method is particularly valuable when there are linkages between projects.

An integrated approach to the lot sizing and cutting stock problems

Various industries consist of the cutting stock and lot-sizing problems in successive stages. Traditionally, these two problems are dealt separately which may adversely affect the overall performance of the supply chain. In this paper, an integrated approach is advocated and a model is proposed to jointly optimize the changeover, inventory holding cost and trim loss for a paper mill. It also defines the sequence of the cutting patterns to be used during conversion process. Moreover, the relationship between the ensuing cycle service levels and the total joint costs is also discussed.

Characteristic Analysis of Mixed Traffic Flow of Regular and Autonomous Vehicles Using Cellular Automata

The technology of autonomous vehicles is expected to revolutionize the operation of road transport systems. The penetration rate of autonomous vehicles will be low at the early stage of their deployment. It is a challenge to explore the effects of autonomous vehicles and their penetration on heterogeneous traffic flow dynamics. This paper aims to investigate this issue. An improved cellular automaton was employed as the modeling platform for our study. In particular, two sets of rules for lane changing were designed to address mild and aggressive lane changing behavior. With extensive simulation studies, we obtained some promising results. First, the introduction of autonomous vehicles to road traffic could considerably improve traffic flow, particularly the road capacity and free-flow speed. And the level of improvement increases with the penetration rate. Second, the lane-changing frequency between neighboring lanes evolves with traffic density along a fundamental-diagram-like curve. Third, the impacts of autonomous vehicles on the collective traffic flow characteristics are mainly related to their smart maneuvers in lane changing and car following, and it seems that the car-following impact is more pronounced.

Adapting principles of developmental biology and agent-based modelling for automated urban residential layout design

The objective is to automate the design of residential layouts as an aid for planners dealing with complex situations. The algorithm COmputational Urban Layout Design, applied to sites with various shapes, is guided by the goal of many mutually accessible residences and can be set to generate orthogonal or irregular road layouts. Using biological principles of genomic equivalence, conditional differentiation and induction, it grows from an embryonic ‘adaptive cell’ into a plan. Cells are ‘genetically identical’ with full development potential and can simultaneously lay roads and residential lots, using the gene set to change cell expression and adapt to local contexts. Cells can be seen as self-propagating agents that sort out their dependencies through local interactions. When COmputational Urban Layout Design is set to grow a non-orthogonal layout, the plan has winding roads and irregular residential lots. Such a plan achieves the objective of relatively high residential density and accessibility, leading to walkable and coherent communities.

Pragmatic Incremental or Courageous Leapfrog [Re]Development of a Land-use and Transport Modelling System for Perth, Australia

Responding to land-use and transport modelling requirements, identified through a rigorous stakeholder engagement process, current land-use and transport modelling practices in Perth, Western Australia were examined and benchmarked against world-wide best practice. Three alternative model systems were proposed and evaluated. The preferred option, PLATINUM (Perth LAnd and Transport INtegrated Urban Model), is the more radical option, avoiding duplication and other resource inefficiencies, yet not discarding specialised and advanced work already undertaken. The unique contextual design challenges relate to the current modelling situation in Perth. It is concluded that designing model systems should explicitly acknowledge the current system in use and solutions should specify the pathway from the existing situation to the new model system. In addition, the two-edged sword of experience should be recognised as both a positive influence in terms of innovation awareness but carefully handled in relation to potential negative influences of path-dependent, ‘incrementality’ at the expense of embracing more radical innovations.

Achieving residential connectivity and density goals with computer-generated plans in a greenfield area

An algorithm has been developed to generate, without external intervention, a road and land-use plan for a regular or irregular site. It starts from an ‘embryo’ and grows a plan rather than trying to modify an initial solution. The basic modules are universal building blocks which change and adapt in a guided search with random selection of branching points followed by operations to add links or make connections. Deletion operators guide development by removing branches which do not improve the outcome. A hypothetical application, maximizing combined everyone-to-everyone connectivity and dwelling density, has evolved a highly interconnected street plan. However, no step is specific to the example; the operators will grow a road and land-use network under various specifications and constraints guided by an objective function. Making the process applicable to an actual development might require more constraints and certainly an enlarged objective function. Cost and other goals can be included so long as each goal is functionally related in some way to every change in the plan made by the search procedure.

Determining the Minimum Wage: A household expenditure approach

The establishment of a minimum wage, a wage below which no employer can pay able bodied full-time employees, is a common feature in most industrialised societies. In many of these societies the minimum wage is determined by government fiat. In Australia, the prevailing method of minimum wage determination has been by way of industrial tribunals. In their minimum wage role both governments and industrial tribunals need to determine minimum wage criteria as well as mechanisms for operationalising the criteria This paper proposes ‘reasonable living’ needs criteria for minimum wage determination. By analysing the Household Expenditure Survey it also suggests the amount which would constitute a ‘reasonable living’ minimum wage for labourers in Australia.