Journal of the Eastern Asia Society for Transportation Studies, 2015
Grave-sweeping is a popular special event in Asia, especially in Chinese societies, in which fami... more Grave-sweeping is a popular special event in Asia, especially in Chinese societies, in which families visit columbaria to express filial piety to their ancestors. The extraordinarily high travel demands usually associated with visiting columbaria during a relative short period around the grave-sweeping festivals severely affect the local traffic. To design and plan adequate transport facilities and services to cater to the travel needs of these families, modeling of their travel demand is a prerequisite procedure. This paper develops and calibrates a non-linear regression model for trip attraction and a joint logit model for trip distribution and modal split using data from headcount and revealed preference surveys collected at selected columbaria during the Ching Ming Festivals of 2013 and 2014. This paper also discusses policy insights gained from the model results that can be applied to the planning of transport facilities and the provision of feeder services to mitigate local co...
This paper proposes an approach-proportion-based variational inequality (VI) formulation for the ... more This paper proposes an approach-proportion-based variational inequality (VI) formulation for the multi-class dynamic traffic assignment problem with physical queues using the concept of intersection movements . To solve the problem, an extragradient method that only requires mild assumptions for convergence is developed. A car-truck interaction paradox, stating that allowing trucks traveling in a network or increasing the demand of trucks traveling in a network could improve the network performance for cars, in terms of total car travel time, is discussed. Numerical examples are set up to illustrate the importance of considering multiple vehicle types and their interaction in a dynamic traffic assignment model and the effects of various parameters on the occurrence of the paradox.
Transportation Research Part D: Transport and Environment, 2019
Abstract Reducing roadside emissions is a common challenge in metropolitan cities. In Hong Kong, ... more Abstract Reducing roadside emissions is a common challenge in metropolitan cities. In Hong Kong, conventional liquefied petroleum gas taxis are one of the main contributors to roadside emissions as they operate on the streets 24 h a day with a long daily driving mileage. Moreover, these taxis suffer from a severely poor service reputation. To enhance the environmental friendliness and service quality of the taxi industry, this study explores the market potential of operating premium electric taxis in the dispatching mode. A stated preference survey was conducted to 1410 taxi customers about their taxi-riding choices between premium electric taxis and conventional liquefied petroleum gas taxis. In total, 5640 observations were obtained and used to develop a series of binary logistic regression models with different model formulations for the determination of the significant factors influencing customers’ selections. The findings indicate that walk time to and wait time for taxis were the most critical concerns to the customers, and they were more willing to take premium taxis if their journey distance was longer and their desired improvement on taxi service quality was greater. The socio-demographic status of taxi customers also influences their choices. The associated policy implications are discussed for promoting taxis with better service quality and fewer roadside emissions. The findings provide some policy insights to other international cities that have a similar taxi market to Hong Kong.
International Journal of Sustainable Transportation, 2019
Abstract There has been a recent surge of research interest in quantifying the health and environ... more Abstract There has been a recent surge of research interest in quantifying the health and environmental impacts of increased cycling in urban environments. Although there is general agreement that the benefits of increased cycling outweigh the risks, most of the methodologies developed have had limited value for evaluating real-world transport policies. This is because they are based on hypothetical scenarios where increased cycling takes place but give no consideration to the courses of action which may help policymakers to achieve the scenarios. A useful extension to these methodologies would be one which allowed a user to find the optimal infrastructure design and/or policies which would maximize total societal benefit, taking into account the health and environmental impacts of cycling. In this study, a Network Design Problem is formulated for systematically designing cycling network layouts in order to maximize the net benefits to the network users and society. The problem is formulated as a mathematical program with equilibrium constraints (MPEC) and a solution approach based on a genetic algorithm (GA) is provided to solve the problem. The problem formulation and solution algorithm are tested using a numerical example. The GA algorithm was shown to efficiently converge to an optimal or near-optimal solution for the cycle network design. The proposed optimization framework may be adopted by transport authorities and/or urban planners as a decision support tool to help them to systematically identify the best design for a cycle network which balances the benefits and risks to all stakeholders.
... NH and C. Stamatiadis (2001).'Combining traffic assignment and adaptive control in a dyn... more ... NH and C. Stamatiadis (2001).'Combining traffic assignment and adaptive control in a dynamic ... Lo, H.(2002),'Trip travel time reliability in degradable transport networks', in MAP Taylor (ed ... Lo, H. and YK Tung (2003),'Network with degradable links: capacity analysis and design ...
Journal of the Eastern Asia Society for Transportation Studies, 2015
Grave-sweeping is a popular special event in Asia, especially in Chinese societies, in which fami... more Grave-sweeping is a popular special event in Asia, especially in Chinese societies, in which families visit columbaria to express filial piety to their ancestors. The extraordinarily high travel demands usually associated with visiting columbaria during a relative short period around the grave-sweeping festivals severely affect the local traffic. To design and plan adequate transport facilities and services to cater to the travel needs of these families, modeling of their travel demand is a prerequisite procedure. This paper develops and calibrates a non-linear regression model for trip attraction and a joint logit model for trip distribution and modal split using data from headcount and revealed preference surveys collected at selected columbaria during the Ching Ming Festivals of 2013 and 2014. This paper also discusses policy insights gained from the model results that can be applied to the planning of transport facilities and the provision of feeder services to mitigate local co...
This paper proposes an approach-proportion-based variational inequality (VI) formulation for the ... more This paper proposes an approach-proportion-based variational inequality (VI) formulation for the multi-class dynamic traffic assignment problem with physical queues using the concept of intersection movements . To solve the problem, an extragradient method that only requires mild assumptions for convergence is developed. A car-truck interaction paradox, stating that allowing trucks traveling in a network or increasing the demand of trucks traveling in a network could improve the network performance for cars, in terms of total car travel time, is discussed. Numerical examples are set up to illustrate the importance of considering multiple vehicle types and their interaction in a dynamic traffic assignment model and the effects of various parameters on the occurrence of the paradox.
Transportation Research Part D: Transport and Environment, 2019
Abstract Reducing roadside emissions is a common challenge in metropolitan cities. In Hong Kong, ... more Abstract Reducing roadside emissions is a common challenge in metropolitan cities. In Hong Kong, conventional liquefied petroleum gas taxis are one of the main contributors to roadside emissions as they operate on the streets 24 h a day with a long daily driving mileage. Moreover, these taxis suffer from a severely poor service reputation. To enhance the environmental friendliness and service quality of the taxi industry, this study explores the market potential of operating premium electric taxis in the dispatching mode. A stated preference survey was conducted to 1410 taxi customers about their taxi-riding choices between premium electric taxis and conventional liquefied petroleum gas taxis. In total, 5640 observations were obtained and used to develop a series of binary logistic regression models with different model formulations for the determination of the significant factors influencing customers’ selections. The findings indicate that walk time to and wait time for taxis were the most critical concerns to the customers, and they were more willing to take premium taxis if their journey distance was longer and their desired improvement on taxi service quality was greater. The socio-demographic status of taxi customers also influences their choices. The associated policy implications are discussed for promoting taxis with better service quality and fewer roadside emissions. The findings provide some policy insights to other international cities that have a similar taxi market to Hong Kong.
International Journal of Sustainable Transportation, 2019
Abstract There has been a recent surge of research interest in quantifying the health and environ... more Abstract There has been a recent surge of research interest in quantifying the health and environmental impacts of increased cycling in urban environments. Although there is general agreement that the benefits of increased cycling outweigh the risks, most of the methodologies developed have had limited value for evaluating real-world transport policies. This is because they are based on hypothetical scenarios where increased cycling takes place but give no consideration to the courses of action which may help policymakers to achieve the scenarios. A useful extension to these methodologies would be one which allowed a user to find the optimal infrastructure design and/or policies which would maximize total societal benefit, taking into account the health and environmental impacts of cycling. In this study, a Network Design Problem is formulated for systematically designing cycling network layouts in order to maximize the net benefits to the network users and society. The problem is formulated as a mathematical program with equilibrium constraints (MPEC) and a solution approach based on a genetic algorithm (GA) is provided to solve the problem. The problem formulation and solution algorithm are tested using a numerical example. The GA algorithm was shown to efficiently converge to an optimal or near-optimal solution for the cycle network design. The proposed optimization framework may be adopted by transport authorities and/or urban planners as a decision support tool to help them to systematically identify the best design for a cycle network which balances the benefits and risks to all stakeholders.
... NH and C. Stamatiadis (2001).'Combining traffic assignment and adaptive control in a dyn... more ... NH and C. Stamatiadis (2001).'Combining traffic assignment and adaptive control in a dynamic ... Lo, H.(2002),'Trip travel time reliability in degradable transport networks', in MAP Taylor (ed ... Lo, H. and YK Tung (2003),'Network with degradable links: capacity analysis and design ...
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Papers by Wai Yuen Szeto