Michael Bell - Academia.edu (original) (raw)

Papers by Michael Bell

Transportation Research Record: Journal of the Transportation Research Board, 2009

Motorcycles constitute a significant proportion of traffic in many countries but are poorly repre... more Motorcycles constitute a significant proportion of traffic in many countries but are poorly represented in existing traffic flow theories and simulation software. A new approach to modeling mixed traffic is introduced focusing on depicting the movements of motorcycles. In this study, the characteristic patterns of motorcycle behavior were identified, and the key elements contributing to these patterns were extracted. Then three mathematical models were developed to depict these key elements, which were calibrated by using field data collected at Victoria Embankment in central London. After the calibration procedures, these models were integrated into an agent-based simulation model system. The ability of the simulator to reproduce plausible patterns of car and motorcycle behavior was verified. A number of potential applications of this simulator for the management of mixed traffic streams in urban areas are discussed.

Transportation Research Part B-Methodological, 2011

This paper transfers the classic frequency-based transit assignment method of Spiess and Florian ... more This paper transfers the classic frequency-based transit assignment method of Spiess and Florian to containers demonstrating its promise as the basis for a global maritime container assignment model. In this model, containers are carried by shipping lines operating strings (or port rotations) with given service frequencies. An origin-destination matrix of full containers is assigned to these strings to minimize sailing time plus container dwell time at the origin port and any intermediate transhipment ports. This necessitated two significant model extensions. The first involves the repositioning of empty containers so that a net outflow of full containers from any port is balanced by a net inflow of empty containers, and vice versa. As with full containers, empty containers are repositioned to minimize the sum of sailing and dwell time, with a facility to discount the dwell time of empty containers in recognition of the absence of inventory. The second involves the inclusion of an upper limit to the maximum number of container moves per unit time at any port. The dual variable for this constraint provides a shadow price, or surcharge, for loading or unloading a container at a congested port. Insight into the interpretation of the dual variables is given by proposition and proof. Model behaviour is illustrated by a simple numerical example. The paper concludes by considering the next steps toward realising a container assignment model that can, amongst other things, support the assessment of supply chain vulnerability to maritime disruptions.

Transportation Research Part E: Logistics and Transportation Review, 2010

This paper studies job assignments for automated guided in container terminal settings under vari... more This paper studies job assignments for automated guided in container terminal settings under various conditions of uncertainty. An introduction to their operation is provided, along with a flexible dispatching algorithm, suitable for real-time control of AGVs. Using these concepts a new AGV dispatching approach is developed, capable of operating under uncertain conditions within a detailed container terminal model. Several performance indicators are presented, focused on generic features of vehicle operations as well the assessment of uncertainty levels inside the terminal. From the results of the simulation experiments, it is found that the proposed technique outperforms well known heuristics and alternative algorithms.

Transportation Research Part B: Methodological, 1997

Road pricmg is now being advocated as an el?icient means of managing traffic demand and of meetin... more Road pricmg is now being advocated as an el?icient means of managing traffic demand and of meeting other objectives, such as reducing the environmental impact of road traffic and improving public transport. This paper shows how a network toll pattern could be determined so as to reduce network travel demand to a desirable level. The demand between each origin4estination pair is described as a function of the generalized travel cost. When there is no toll charge, higher values of potential demand might cause congestion and queuing at bottleneck links of the road network. Queuing delay at saturated links may grow to choke off enough potential demand to reduce realized demand to the capacity of the network. thus leading to a queuing equilibrium where travel demand and travel cost match each other. In this paper, we first show how an elastic-demand network equilibrium model with queue could be used to determine this demand-~ supply equilibrium. We then seek a link toll pattern to remove the wasteful queuing delay, and/or restrain the realized demand to a desirable level to satisfy environment capacity constraints. We also show that the link toll pattern that could hold the traffic demand to a desirable level is not unique, a bi-level programming method is developed to select the best toll pattern among the feasible solutions based on pre-specified criteria.

Transportation Research Part B: Methodological, 2001

The continuous network design problem (CNDP) is characterized by a bilevel programming model and ... more The continuous network design problem (CNDP) is characterized by a bilevel programming model and recognized to be one of the most dicult and challenging problems in transportation. The main diculty stems from the fact that the bilevel formulation for the CNDP is nonconvex and nondierentiable, and indeed only some heuristic methods have been so far proposed. In this paper, the bilevel programming model for CNDPs is transferred into a single level optimization problem by virtue of a marginal function tool. By exploring the inherent nature of the CNDP, the marginal function for the lower-level user equilibrium problem is proved to be continuously dierentiable and its functional value and derivative in link capacity enhancement can be obtained eciently by implementing a user equilibrium assignment subroutine. Thus a continuously dierentiable but still nonconvex optimization formulation of the CNDP is created and a locally convergent augmented Lagrangian method is applied to solve this equivalent problem. The descent direction in each step of the inner loop of the solution method can be found by doing an all or nothing assignment. These favorable characteristics indicate the potential of the algorithm to solve large CNDPs. Numerical examples are presented to compare the proposed method with some existing algorithms.

Transportation Research Part B: Methodological, 2001

Transportation Research Part B: Methodological, 2000

Consider an urban transportation network. For a given current origin±destination (O±D) demand pat... more Consider an urban transportation network. For a given current origin±destination (O±D) demand pattern, we can have a corresponding link¯ow pattern on the network through an appropriate equilibrium trac assignment model. Supposing that¯ow on each link associated with the current O±D demand is below a given upper bound such as link capacity or any other prescribed threshold, we would ask how much additional demand from each trip origin can be accommodated by the network so that¯ow on each link is still within the given bound when the additional and existing demand is together assigned to the network. This problem can be referred to as the network capacity and level of service problem and is fully investigated in this paper. New formulations are presented and compared with existing techniques in terms of the assumption of O±D demand pattern and travelers' route and location choice behavior for the capacity and level of service modeling. Numerical examples are provided and potential applications of the models are mentioned.

Transportation Research Part B: Methodological, 2014

Areas subject to natural or man-made disasters, such as earthquakes, fires, floods or attacks, ar... more Areas subject to natural or man-made disasters, such as earthquakes, fires, floods or attacks, are reliant on the residual transport network for the rescue of survivors and subsequent recovery. Pre-disaster planning requires assumptions about how the transport network may degrade. This paper presents a game theoretic approach modelling network degradation and applies this to depot location, with a case study based on Sichuan province in China, which is prone to earthquakes. To facilitate a cautious approach to depot location, the method assumes that the transport network is subject to attack by node-specific demons with the power to degrade links. The mixed strategy Nash equilibrium for the non-cooperative zero sum game between dispatchers and demons is used to define rescue hyperpaths. These in turn define the best depot locations. Two forms of the drop heuristic are used to find good depot locations.

Transportation Research Part A: Policy and Practice, 2005

The theory and practice of congestion charging In August 2003, a group of experts from around the... more The theory and practice of congestion charging In August 2003, a group of experts from around the world came together at Imperial College London to discuss the theory and practice of congestion charging. The meeting was organised to celebrate the life of Professor Peter Hills, whose contributions to the field had inspired many, and to capitalise on the introduction of congestion charging in London during the preceding February. Over 100 attendees came to hear 39 presentations, demonstrating both the depth of interest and the breadth of the topic. This special issue constitutes the selected proceedings of the symposium. The theory of road pricing has long been studied, with the earliest notable literature dating back to the pioneering works of Dupuit in 1844 and Pigou in 1920. As economic, environmental, and sustainability considerations added to the need to develop policies to counter traffic congestion, the topic of congestion charging has attracted the attention of an increasing number of scholars, leading to innovative proposals to tackle the problem. Much of the debate on congestion modelling concerns the apparent conflict between the monotone increasing link cost functions commonly used in static traffic assignment, which have their routes in steady state queuing theory, and the non-monotone ''backward-bending'' link cost functions proposed for dynamic traffic assignment, which have their routes in both time-dependent queuing theory and traffic flow theory. This conflict lies at the core of the so-called Hills-Evans debate, pursued so energetically by the late Peter Hills. Lo and Szeto (2005) suggest that monotone link cost functions are inappropriate in modelling congestion charges when queue spillback (sometimes referred to as hyper-congestion) occurs. The use of monotone link cost functions could, in some cases, lead to the calculation and implementation of incorrect congestion charges, resulting in a worsening of the original problem. In a contrasting approach to the same problem of ''backward-bending'' link cost functions, Verhoef (2005) used car following theory to study hyper-congestion. Rather than confirming the existence of a backward-bend in link cost functions, he demonstrated instability under hyper-congestion which, when average values are plotted, gives the appearance of a backward bend. It is fitting that a reconciliation of the conflicting positions in the Hills-Evans debate should be found in this special issue.

The Annals of Regional Science, 2000

For studying carpooling problems, this paper presents two models, namely deterministic and stocha... more For studying carpooling problems, this paper presents two models, namely deterministic and stochastic, and gives the economic explanations to the model solutions. We investigate the jockeying behavior of work commuters between carpooling and driving alone modes through solving each model for both no-toll equilibrium and social optimum. The logit-based stochastic model involves the consideration on preference option of mode choice. Under some assumptions, the paper explains how the amount of carpooling is a¨ected by fuel cost, assembly cost, value of time, preferential or attitudinal factors and tra½c congestion. It is found that carpooling is sensitive to tra½c congestion reduction only when a congestion externality-based tolling scheme is implemented.

Research in Transportation Economics, 2009

Entering the 21st century, one of the most significant demographic changes in developed countries... more Entering the 21st century, one of the most significant demographic changes in developed countries is the aging of the population. Travel is an important aspect of older people's economic well-being, so with the aging of the population, improving transport for older people is increasingly important. This article presents the results of a study of older people's travel behaviour based largely but not exclusively on LATS (London Area Travel Survey) 2001 data. The focus is on older people's trip chaining behaviour, including trip chain complexity, trip purpose sequence and mode choice in a chain. After identifying the policy implications it looks at the role of Special Transport Services in improving the supply of transport for older people, taking the London Borough of Camden as a case study.

Maritime Policy & Management, 2011

Simulation has been an integral part of research and development work in container terminal opera... more Simulation has been an integral part of research and development work in container terminal operations. The sheer size of the facilities and the complexity of equipment used make it difficult to predict analytically how the terminal will operate under specific layouts and configurations. Control techniques which relate to the dynamic behaviour of the equipment are even more difficult to analyse and benchmark, therefore necessitating the presence of a tool that can replicate the behaviour of a real terminal. This paper provides ...

During September 2000 a wave of popular unrest over the price of petrol gripped several European ... more During September 2000 a wave of popular unrest over the price of petrol gripped several European countries. In the UK, these protests led to oil refineries being blockaded resulting in severe fuel shortages, which in turn forced many drivers to restrict their car use and make adaptations in their travel behaviour. These changes in behaviour were potentially of a nature and scale not normally associated with conventional transport policy interventions. The incidence of these 'coerced responses' provided a unique opportunity to study the mechanisms of adaptation involved in significant reductions in car use and to gain insight into the consequences of these adaptations for the individuals concerned, both in the short and longer term. The aim of this paper is to present the results of a study carried out to investigate the nature of these responses and to discuss the implications of the findings for travel demand management and travel reduction policies. The study was carried out shortly after the end of the UK fuel crisis and involved a combination of two methodologies. First, three group discussions were undertaken in two urban and one rural area in the UK to investigate the qualitative impact of the fuel shortage on individuals' travel patterns and activity participation and to gain insight into the mechanisms of behavioural adaptation, including the factors that act as inhibitors of adaptation. These group discussions were then followed up in the second stage with a nationally representative telephone survey that collected quantitative information on the severity of the impact of fuel shortages on different activities and travel purposes and the incidence of different form of behavioural response. The paper is organised as follows. The first section describes the background to the study and briefly reviews the existing literature on the nature of behavioural responses manifest in 'coercive' situations e.g., in instances of major transport system failures or natural disasters. The second section then summarises the key features of the study methodology and presents summary data on the characteristics of the qualitative and quantitative samples. The third section presents the key descriptive findings from the qualitative and quantitative data. Tentative findings available at this stage suggest that the impact of the September 2000 fuel crisis was perhaps neither as extensive nor intensive as media reports at the time suggested, but that longer periods of uncertainty regarding fuel supplies would indeed have profound effects upon travel patterns, especially commuting, travel in the course of work and shopping. The results also indicate that travellers would be likely to invoke a wide range of behavioural responses, including both those that are well-researched (such as mode and destination switching) and, significantly, those that are not (such as trip chain re-scheduling and modifications to driving style). Both impacts and responses differ significantly in urban and rural areas. The final section explores the policy implications of these findings and identifies future research and policy needs. For the covering abstract see ITRD E115303.

... The authors would like to thank the John Lewis Partnership and the London Retail Consortium f... more ... The authors would like to thank the John Lewis Partnership and the London Retail Consortium for permission to analyse the sales data and Transport for London for funding the study. ... Quddus et al. (2005), analysing weekly sales data for six John Lewis ...

Navigationsgeräte sind mittlerweile ein fast selbstverständlicher Teil des auto mobilen Lebens un... more Navigationsgeräte sind mittlerweile ein fast selbstverständlicher Teil des auto mobilen Lebens und stellen neben dem Verkehrsfunk die wichtigste Informationsquelle im Fahrzeug dar. Vor allem in den letzten Jahren sind neben den fest installierten Geräten auch mobile Navigationsgeräte zu günstigen Preisen am Markt erhältlich. Prognosen zeigen, dass in wenigen Jahren ein großer Teil der Fahrzeuge mit einem Navigationsgerät ausgestattet sein wird. Ziel der reinen Zielführungsfunktion eines Navigationsgerätes ist es, vom aktuellen, meist durch Satellitenortung errechneten, Standpunkt des Fahrzeugs entweder die zeitlich schnellste oder räumlich kürzeste Route zum eingegebenen Bestimmungsort zu finden. Neben der reinen Zielführungsfunktion, die vor allem dem Fahrer in einer ihm unbekannten oder unvertrauten Umgebung hilft, gewinnt die sogenannte „dynamische Zielführung“ immer mehr an Bedeutung. Dabei werden aktuelle Verkehrsinformationen, z. B. per TMC, bei der Routenberechnung berücksich...

2012 15th International IEEE Conference on Intelligent Transportation Systems, 2012

Metropolitan areas today have become more than ever saturated with various types and sources of r... more Metropolitan areas today have become more than ever saturated with various types and sources of real-time data. Yet, the unsolved practical challenge how to most effectively combine data sources currently prevents the wide use of this data as a powerful tool to both improve the quality of the transport supply and to influence travel demand. Focusing on London, this paper investigates the current state and attempts to give an outlook into the future of traffic data fusion in dense urban network environments. Successes and gaps in the current state are identified, and extensions are proposed, along with respective deployment scenarios and impacts assessment.

2012 15th International IEEE Conference on Intelligent Transportation Systems, 2012

The London Congestion Charging (LCC) scheme was initially introduced on 17 February 2003. Being t... more The London Congestion Charging (LCC) scheme was initially introduced on 17 February 2003. Being the largest of its kind and employing advanced technology, it marked a major innovation in the field of urban road user charging and provided inspiration to several other cities worldwide. Nine years on, and following a number of operational changes that have taken place, this study analyzes successes and pitfalls, and identifies potential future opportunities in the light of latest technological developments in the field of cooperative Intelligent Transport Systems (ITS). The analysis concentrates primarily on the LCC scheme itself, but draws broader conclusions about the future of urban road charging in general.

Transportation Research Record: Journal of the Transportation Research Board, 2010

This paper examines the development, use, and evaluation of a new traffic conflict analysis techn... more This paper examines the development, use, and evaluation of a new traffic conflict analysis technique that specifically addresses pedestrian–vehicle conflicts with the intention of being applicable to shared-space environments. The method is based on an existing, well-established, and widely used vehicle–vehicle conflict analysis technique, but is adapted to consider the movement of pedestrians, which differs significantly from that of vehicles. The new method is then implemented on the Exhibition Road site of West London with the use of video data collected from locations with a potentially high concentration of vehicle–pedestrian conflicts, and the results of the analysis are presented. Finally, the results are compared with those obtained by other conflict analysis techniques and also against accident data to assess not only the accuracy but also the functionality of the new technique.

Transportation Research Record: Journal of the Transportation Research Board, 2009

Motorcycles constitute a significant proportion of traffic in many countries but are poorly repre... more Motorcycles constitute a significant proportion of traffic in many countries but are poorly represented in existing traffic flow theories and simulation software. A new approach to modeling mixed traffic is introduced focusing on depicting the movements of motorcycles. In this study, the characteristic patterns of motorcycle behavior were identified, and the key elements contributing to these patterns were extracted. Then three mathematical models were developed to depict these key elements, which were calibrated by using field data collected at Victoria Embankment in central London. After the calibration procedures, these models were integrated into an agent-based simulation model system. The ability of the simulator to reproduce plausible patterns of car and motorcycle behavior was verified. A number of potential applications of this simulator for the management of mixed traffic streams in urban areas are discussed.

Transportation Research Part B-Methodological, 2011

This paper transfers the classic frequency-based transit assignment method of Spiess and Florian ... more This paper transfers the classic frequency-based transit assignment method of Spiess and Florian to containers demonstrating its promise as the basis for a global maritime container assignment model. In this model, containers are carried by shipping lines operating strings (or port rotations) with given service frequencies. An origin-destination matrix of full containers is assigned to these strings to minimize sailing time plus container dwell time at the origin port and any intermediate transhipment ports. This necessitated two significant model extensions. The first involves the repositioning of empty containers so that a net outflow of full containers from any port is balanced by a net inflow of empty containers, and vice versa. As with full containers, empty containers are repositioned to minimize the sum of sailing and dwell time, with a facility to discount the dwell time of empty containers in recognition of the absence of inventory. The second involves the inclusion of an upper limit to the maximum number of container moves per unit time at any port. The dual variable for this constraint provides a shadow price, or surcharge, for loading or unloading a container at a congested port. Insight into the interpretation of the dual variables is given by proposition and proof. Model behaviour is illustrated by a simple numerical example. The paper concludes by considering the next steps toward realising a container assignment model that can, amongst other things, support the assessment of supply chain vulnerability to maritime disruptions.

Transportation Research Part E: Logistics and Transportation Review, 2010

This paper studies job assignments for automated guided in container terminal settings under vari... more This paper studies job assignments for automated guided in container terminal settings under various conditions of uncertainty. An introduction to their operation is provided, along with a flexible dispatching algorithm, suitable for real-time control of AGVs. Using these concepts a new AGV dispatching approach is developed, capable of operating under uncertain conditions within a detailed container terminal model. Several performance indicators are presented, focused on generic features of vehicle operations as well the assessment of uncertainty levels inside the terminal. From the results of the simulation experiments, it is found that the proposed technique outperforms well known heuristics and alternative algorithms.

Transportation Research Part B: Methodological, 1997

Road pricmg is now being advocated as an el?icient means of managing traffic demand and of meetin... more Road pricmg is now being advocated as an el?icient means of managing traffic demand and of meeting other objectives, such as reducing the environmental impact of road traffic and improving public transport. This paper shows how a network toll pattern could be determined so as to reduce network travel demand to a desirable level. The demand between each origin4estination pair is described as a function of the generalized travel cost. When there is no toll charge, higher values of potential demand might cause congestion and queuing at bottleneck links of the road network. Queuing delay at saturated links may grow to choke off enough potential demand to reduce realized demand to the capacity of the network. thus leading to a queuing equilibrium where travel demand and travel cost match each other. In this paper, we first show how an elastic-demand network equilibrium model with queue could be used to determine this demand-~ supply equilibrium. We then seek a link toll pattern to remove the wasteful queuing delay, and/or restrain the realized demand to a desirable level to satisfy environment capacity constraints. We also show that the link toll pattern that could hold the traffic demand to a desirable level is not unique, a bi-level programming method is developed to select the best toll pattern among the feasible solutions based on pre-specified criteria.

Transportation Research Part B: Methodological, 2001

The continuous network design problem (CNDP) is characterized by a bilevel programming model and ... more The continuous network design problem (CNDP) is characterized by a bilevel programming model and recognized to be one of the most dicult and challenging problems in transportation. The main diculty stems from the fact that the bilevel formulation for the CNDP is nonconvex and nondierentiable, and indeed only some heuristic methods have been so far proposed. In this paper, the bilevel programming model for CNDPs is transferred into a single level optimization problem by virtue of a marginal function tool. By exploring the inherent nature of the CNDP, the marginal function for the lower-level user equilibrium problem is proved to be continuously dierentiable and its functional value and derivative in link capacity enhancement can be obtained eciently by implementing a user equilibrium assignment subroutine. Thus a continuously dierentiable but still nonconvex optimization formulation of the CNDP is created and a locally convergent augmented Lagrangian method is applied to solve this equivalent problem. The descent direction in each step of the inner loop of the solution method can be found by doing an all or nothing assignment. These favorable characteristics indicate the potential of the algorithm to solve large CNDPs. Numerical examples are presented to compare the proposed method with some existing algorithms.

Transportation Research Part B: Methodological, 2001

Transportation Research Part B: Methodological, 2000

Consider an urban transportation network. For a given current origin±destination (O±D) demand pat... more Consider an urban transportation network. For a given current origin±destination (O±D) demand pattern, we can have a corresponding link¯ow pattern on the network through an appropriate equilibrium trac assignment model. Supposing that¯ow on each link associated with the current O±D demand is below a given upper bound such as link capacity or any other prescribed threshold, we would ask how much additional demand from each trip origin can be accommodated by the network so that¯ow on each link is still within the given bound when the additional and existing demand is together assigned to the network. This problem can be referred to as the network capacity and level of service problem and is fully investigated in this paper. New formulations are presented and compared with existing techniques in terms of the assumption of O±D demand pattern and travelers' route and location choice behavior for the capacity and level of service modeling. Numerical examples are provided and potential applications of the models are mentioned.

Transportation Research Part B: Methodological, 2014

Areas subject to natural or man-made disasters, such as earthquakes, fires, floods or attacks, ar... more Areas subject to natural or man-made disasters, such as earthquakes, fires, floods or attacks, are reliant on the residual transport network for the rescue of survivors and subsequent recovery. Pre-disaster planning requires assumptions about how the transport network may degrade. This paper presents a game theoretic approach modelling network degradation and applies this to depot location, with a case study based on Sichuan province in China, which is prone to earthquakes. To facilitate a cautious approach to depot location, the method assumes that the transport network is subject to attack by node-specific demons with the power to degrade links. The mixed strategy Nash equilibrium for the non-cooperative zero sum game between dispatchers and demons is used to define rescue hyperpaths. These in turn define the best depot locations. Two forms of the drop heuristic are used to find good depot locations.

Transportation Research Part A: Policy and Practice, 2005

The theory and practice of congestion charging In August 2003, a group of experts from around the... more The theory and practice of congestion charging In August 2003, a group of experts from around the world came together at Imperial College London to discuss the theory and practice of congestion charging. The meeting was organised to celebrate the life of Professor Peter Hills, whose contributions to the field had inspired many, and to capitalise on the introduction of congestion charging in London during the preceding February. Over 100 attendees came to hear 39 presentations, demonstrating both the depth of interest and the breadth of the topic. This special issue constitutes the selected proceedings of the symposium. The theory of road pricing has long been studied, with the earliest notable literature dating back to the pioneering works of Dupuit in 1844 and Pigou in 1920. As economic, environmental, and sustainability considerations added to the need to develop policies to counter traffic congestion, the topic of congestion charging has attracted the attention of an increasing number of scholars, leading to innovative proposals to tackle the problem. Much of the debate on congestion modelling concerns the apparent conflict between the monotone increasing link cost functions commonly used in static traffic assignment, which have their routes in steady state queuing theory, and the non-monotone ''backward-bending'' link cost functions proposed for dynamic traffic assignment, which have their routes in both time-dependent queuing theory and traffic flow theory. This conflict lies at the core of the so-called Hills-Evans debate, pursued so energetically by the late Peter Hills. Lo and Szeto (2005) suggest that monotone link cost functions are inappropriate in modelling congestion charges when queue spillback (sometimes referred to as hyper-congestion) occurs. The use of monotone link cost functions could, in some cases, lead to the calculation and implementation of incorrect congestion charges, resulting in a worsening of the original problem. In a contrasting approach to the same problem of ''backward-bending'' link cost functions, Verhoef (2005) used car following theory to study hyper-congestion. Rather than confirming the existence of a backward-bend in link cost functions, he demonstrated instability under hyper-congestion which, when average values are plotted, gives the appearance of a backward bend. It is fitting that a reconciliation of the conflicting positions in the Hills-Evans debate should be found in this special issue.

The Annals of Regional Science, 2000

For studying carpooling problems, this paper presents two models, namely deterministic and stocha... more For studying carpooling problems, this paper presents two models, namely deterministic and stochastic, and gives the economic explanations to the model solutions. We investigate the jockeying behavior of work commuters between carpooling and driving alone modes through solving each model for both no-toll equilibrium and social optimum. The logit-based stochastic model involves the consideration on preference option of mode choice. Under some assumptions, the paper explains how the amount of carpooling is a¨ected by fuel cost, assembly cost, value of time, preferential or attitudinal factors and tra½c congestion. It is found that carpooling is sensitive to tra½c congestion reduction only when a congestion externality-based tolling scheme is implemented.

Research in Transportation Economics, 2009

Entering the 21st century, one of the most significant demographic changes in developed countries... more Entering the 21st century, one of the most significant demographic changes in developed countries is the aging of the population. Travel is an important aspect of older people's economic well-being, so with the aging of the population, improving transport for older people is increasingly important. This article presents the results of a study of older people's travel behaviour based largely but not exclusively on LATS (London Area Travel Survey) 2001 data. The focus is on older people's trip chaining behaviour, including trip chain complexity, trip purpose sequence and mode choice in a chain. After identifying the policy implications it looks at the role of Special Transport Services in improving the supply of transport for older people, taking the London Borough of Camden as a case study.

Maritime Policy & Management, 2011

Simulation has been an integral part of research and development work in container terminal opera... more Simulation has been an integral part of research and development work in container terminal operations. The sheer size of the facilities and the complexity of equipment used make it difficult to predict analytically how the terminal will operate under specific layouts and configurations. Control techniques which relate to the dynamic behaviour of the equipment are even more difficult to analyse and benchmark, therefore necessitating the presence of a tool that can replicate the behaviour of a real terminal. This paper provides ...

During September 2000 a wave of popular unrest over the price of petrol gripped several European ... more During September 2000 a wave of popular unrest over the price of petrol gripped several European countries. In the UK, these protests led to oil refineries being blockaded resulting in severe fuel shortages, which in turn forced many drivers to restrict their car use and make adaptations in their travel behaviour. These changes in behaviour were potentially of a nature and scale not normally associated with conventional transport policy interventions. The incidence of these 'coerced responses' provided a unique opportunity to study the mechanisms of adaptation involved in significant reductions in car use and to gain insight into the consequences of these adaptations for the individuals concerned, both in the short and longer term. The aim of this paper is to present the results of a study carried out to investigate the nature of these responses and to discuss the implications of the findings for travel demand management and travel reduction policies. The study was carried out shortly after the end of the UK fuel crisis and involved a combination of two methodologies. First, three group discussions were undertaken in two urban and one rural area in the UK to investigate the qualitative impact of the fuel shortage on individuals' travel patterns and activity participation and to gain insight into the mechanisms of behavioural adaptation, including the factors that act as inhibitors of adaptation. These group discussions were then followed up in the second stage with a nationally representative telephone survey that collected quantitative information on the severity of the impact of fuel shortages on different activities and travel purposes and the incidence of different form of behavioural response. The paper is organised as follows. The first section describes the background to the study and briefly reviews the existing literature on the nature of behavioural responses manifest in 'coercive' situations e.g., in instances of major transport system failures or natural disasters. The second section then summarises the key features of the study methodology and presents summary data on the characteristics of the qualitative and quantitative samples. The third section presents the key descriptive findings from the qualitative and quantitative data. Tentative findings available at this stage suggest that the impact of the September 2000 fuel crisis was perhaps neither as extensive nor intensive as media reports at the time suggested, but that longer periods of uncertainty regarding fuel supplies would indeed have profound effects upon travel patterns, especially commuting, travel in the course of work and shopping. The results also indicate that travellers would be likely to invoke a wide range of behavioural responses, including both those that are well-researched (such as mode and destination switching) and, significantly, those that are not (such as trip chain re-scheduling and modifications to driving style). Both impacts and responses differ significantly in urban and rural areas. The final section explores the policy implications of these findings and identifies future research and policy needs. For the covering abstract see ITRD E115303.

... The authors would like to thank the John Lewis Partnership and the London Retail Consortium f... more ... The authors would like to thank the John Lewis Partnership and the London Retail Consortium for permission to analyse the sales data and Transport for London for funding the study. ... Quddus et al. (2005), analysing weekly sales data for six John Lewis ...

Navigationsgeräte sind mittlerweile ein fast selbstverständlicher Teil des auto mobilen Lebens un... more Navigationsgeräte sind mittlerweile ein fast selbstverständlicher Teil des auto mobilen Lebens und stellen neben dem Verkehrsfunk die wichtigste Informationsquelle im Fahrzeug dar. Vor allem in den letzten Jahren sind neben den fest installierten Geräten auch mobile Navigationsgeräte zu günstigen Preisen am Markt erhältlich. Prognosen zeigen, dass in wenigen Jahren ein großer Teil der Fahrzeuge mit einem Navigationsgerät ausgestattet sein wird. Ziel der reinen Zielführungsfunktion eines Navigationsgerätes ist es, vom aktuellen, meist durch Satellitenortung errechneten, Standpunkt des Fahrzeugs entweder die zeitlich schnellste oder räumlich kürzeste Route zum eingegebenen Bestimmungsort zu finden. Neben der reinen Zielführungsfunktion, die vor allem dem Fahrer in einer ihm unbekannten oder unvertrauten Umgebung hilft, gewinnt die sogenannte „dynamische Zielführung“ immer mehr an Bedeutung. Dabei werden aktuelle Verkehrsinformationen, z. B. per TMC, bei der Routenberechnung berücksich...

2012 15th International IEEE Conference on Intelligent Transportation Systems, 2012

Metropolitan areas today have become more than ever saturated with various types and sources of r... more Metropolitan areas today have become more than ever saturated with various types and sources of real-time data. Yet, the unsolved practical challenge how to most effectively combine data sources currently prevents the wide use of this data as a powerful tool to both improve the quality of the transport supply and to influence travel demand. Focusing on London, this paper investigates the current state and attempts to give an outlook into the future of traffic data fusion in dense urban network environments. Successes and gaps in the current state are identified, and extensions are proposed, along with respective deployment scenarios and impacts assessment.

2012 15th International IEEE Conference on Intelligent Transportation Systems, 2012

The London Congestion Charging (LCC) scheme was initially introduced on 17 February 2003. Being t... more The London Congestion Charging (LCC) scheme was initially introduced on 17 February 2003. Being the largest of its kind and employing advanced technology, it marked a major innovation in the field of urban road user charging and provided inspiration to several other cities worldwide. Nine years on, and following a number of operational changes that have taken place, this study analyzes successes and pitfalls, and identifies potential future opportunities in the light of latest technological developments in the field of cooperative Intelligent Transport Systems (ITS). The analysis concentrates primarily on the LCC scheme itself, but draws broader conclusions about the future of urban road charging in general.

Transportation Research Record: Journal of the Transportation Research Board, 2010

This paper examines the development, use, and evaluation of a new traffic conflict analysis techn... more This paper examines the development, use, and evaluation of a new traffic conflict analysis technique that specifically addresses pedestrian–vehicle conflicts with the intention of being applicable to shared-space environments. The method is based on an existing, well-established, and widely used vehicle–vehicle conflict analysis technique, but is adapted to consider the movement of pedestrians, which differs significantly from that of vehicles. The new method is then implemented on the Exhibition Road site of West London with the use of video data collected from locations with a potentially high concentration of vehicle–pedestrian conflicts, and the results of the analysis are presented. Finally, the results are compared with those obtained by other conflict analysis techniques and also against accident data to assess not only the accuracy but also the functionality of the new technique.