Anthony Chen

• PhD
• Professor (Full) at The Hong Kong Polytechnic University

During and after a disaster, people share resources with family, friends and neighbors to tide them over difficult times. The conventional top-down approach for disaster relief overlooks the wealth of critical resources that exist within communities. Here we explicitly model place-based peer-to-peer (P2P) resource sharing and evaluate its impact on...

We extend congestion games to the setting where players need to make multiple joint choices with interactions in a hierarchical manner (termed joint congestion game). At each choice dimension, players are involved in a typical congestion game. This game has a feature that the output of one choice dimension serves as an input of another one, and the...

Traditional transportation planning emphasized the direct economic benefits of transportation infrastructure. While there is a growing awareness of the environmental consequences, social impacts are frequently overlooked due to methodological complexities and political neglect. Although existing literature acknowledges the existence of transportati...

Understanding how people choose routes in urban environments is essential for effective urban planning. While conventional transportation studies focus on utilitarian decision-making, this research investigates the complex interplay between human-environment interactions and emotional attachments to places, which influence transportation choices. S...

Electrified transit is crucial for promoting zero-emission transportation in metropolitan cities. However, this initiative faces considerable challenges in Hong Kong due to limited space available for parking and refueling bus fleets. Despite the inexpensive operational costs of battery electric buses (BEBs), plenty of space is required to park and...

Infrastructure networks play pivotal roles by facilitating social interactions and economic activities. Nonetheless, these networks are susceptible to disruptive influences such as natural disasters. In response to such disruptions, decision-makers must undertake efficient allocation of recovery projects to restore to a pre-disruption state. With s...

In urban transportation network, the formation of traffic congestion is often caused by link capacity constraints, which is often accompanied by physical queuing phenomena. This paper proposes a bi-modal mixed traffic equilibrium model with capacity constraints under two cases: (1) the physical queuing case for both car and bus modes; (2) implement...

In this paper, we study the elastic-demand bi-criteria traffic assignment problem under the continuously distributed value of time, referred to as the ED-CBiTA problem for simplicity. Specifically, the origin and destination (O-D) demand of ED-CBiTA is endogenously guided by the expected generalized travel time aggregated from all efficient paths,...

Transit-oriented development (TOD) aims to create pedestrian-friendly neighborhoods around transit hubs to improve urban mobility. However, it often overlooks the specific transportation needs of people with limited mobility. This study adopts Sen’s capabilities approach (CA) and the concept of conversion factors to analyze how ordinary pedestrians...

This paper studied the range-constrained traffic assignment problem (RTAP), where heterogeneous range anxiety is considered among the driving population by electric vehicles (EVs). In order not to get stranded en-route, each EV driver is assumed to have his/her own driving range limit for being able to complete the trip. As a result, two types of m...

The reliability and unreliability of travel time variability caused by stochastic train delays considerably influence passengers' travel path choices. This paper proposes an equilibrium assignment method that can capture the passengers' path choice behaviors considering both the reliability and unreliability of travel time variability in the railwa...

Braess proposed one of the classical traffic paradoxes in 1968, which states that adding a link in a transportation network may increase the travel cost for all travelers in the network. The paradox attracted substantial scholarly attention and research. However, there are many other paradoxical phenomena in the transportation field, which we call...

In this paper, we focus on the multiclass bi-criteria (time and toll) traffic assignment (MBTA) problem. The conventional MBTA model keeps multiple copies of class-specific variables to model user heterogeneity, which puts a great burden on memory storage and computational speed when dealing with real transportation networks. This paper proposes an...

This study proposes an optimization-based approach to rank the importance of link combinations and analyze network vulnerability in extreme and near-extreme cases of disruption under the simultaneous disruption of multiple links. A vulnerability envelope concept is used, which considers the worst and best network performance under multiple-link dis...

Pedestrian infrastructures in Hong Kong enable multilevel city life in a vertical metropolis plagued by land scarcity. Public spaces integrated into pedestrian networks play an indispensable role in neighbourhood accessibility. We visualize the impact of the Covid-19 vaccine passport (VP) restrictions on the use of public space on pedestrian access...

Once an urban rail transit (URT) system breaks down or is deliberately damaged, it will cause tremendous pressure on the whole urban transportation system. Hence, its ability to deal with incidents has become an important research field. Existing studies seldom consider the entire cycle of an incident and ignore changes in passenger travel behavior...

Given the increasing prevalence of new urban transport modes such as ridesharing, e-hailing, and combined transport, it is essential to evaluate their effects on the capacity of transportation networks. Hence, this paper develops a novel transportation network capacity model to capture the travel behaviors of inter-multimodal mobility in an urban t...

The unavoidable travel time variability in transportation networks, resulted from the widespread supply-side and demand-side uncertainties, makes travel time reliability (TTR) be a common and core interest of all of the stakeholders in transportation systems, including planners, travelers, service providers, and managers. This common and core inter...

This paper presents a proof-of-concept designer-in-the-loop schematic map drawing tool, based on the marriage of two approaches – manual and automated, which provides the technical interactivity of drawing tools between the user and the computer. We focus on concentric circle maps as opposed to the commonly used orthogonal mode representation, whic...

The intensive development of the metro system has enabled the building of underground infrastructure that facilitates pedestrian movement from below ground to the surface, and between surface areas. However, it is unclear how willing residents are to use the network of underground spaces of newly built stations as a pedestrian system parallel to th...

The intensive development of the metro system has enabled the building of underground infrastructure that facilitates pedestrian movement from below ground to the surface, and between surface areas. However, it is unclear how willing residents are to use the network of underground spaces of newly built stations as a pedestrian system parallel to th...

Network capacity, defined as the largest sum of origin–destination (O–D) flows that can be accommodated by the network based on link performance function and traffic equilibrium assignment, is a critical indicator of network-wide performance assessment in transportation planning and management. The typical modeling rationale of estimating network c...

The concentric circles (CC) map design is an alternative approach for schematically representing metro systems. Compared with traditional octo-linear maps, CC maps can effectively simplify the perception of a network by visually accenting circular line patterns. This design offers new insights into the schematic drawing of metro systems that can im...

Extensive empirical studies show that the long distribution tail of travel time and the corresponding unexpected delay can have much more serious consequences than expected or moderate delay. However, the unexpected delay due to the unreliable aspect of travel time has received limited attention in recent studies of the valuation of travel time var...

The unavoidable travel time variability in transportation networks, resulted from the widespread supply side and demand side uncertainties, makes travel time reliability (TTR) be a common and core interest of all of the stakeholders in transportation systems, including planners, travelers, service providers, and managers. This common and core inter...

Many app-based transportation services provide waiting time information to users before they book the services. Travel time is an important component of waiting time, and positive skew with a long upper tail is a basic characteristic of travel time variability. Waiting time information provision is expected to be reliable and easy to understand. Ho...

Vehicle capacity and number-of-transfers constraints are critical in transit network equilibrium because (1) transit vehicles cannot carry passengers over their capacity and (2) transit passengers typically avoid paths with numerous transfers. In this paper, we propose a strategy-based transit stochastic user equilibrium (SUE) model that considers...

Three-dimensional transportation space is one of the most important characteristics of multi-layered cities; however, fine-scale built environment factors about facilities that support the 3D walking environment were unavailable in understanding travelers’ behaviors before heading to the Big Data era. Using both small (questionnaire survey) and big...

Transportation network capacity is an important indicator from measuring the performance of a transportation system. Previous studies on the capacity of multimodal networks have not considered transfers between different transportation modes. In fact, because of the diversified development of the urban transportation system, travelers are no longer...

Travel time is important for both users and planners. Travel time variability widely exists in transportation systems. Positive skew with a long/fat upper tail is a basic characteristic of travel time variability, which poses great challenges to reporting travel time information to the public. There are two main approaches for disseminating travel...

Accessibility and mobility are positioned differently at the heart of transportation planning; whist a transportation system with high accessibility is not necessarily be able to support high mobility. In this short article, we evaluate and visualize the accessibility and mobility of pedestrian networks around the metro station areas in a transit-o...

Systematic uncertainty analysis can be used to quantitatively evaluate variation in model outputs and identify the critical sources of uncertainty to improve the reliability and stability of a system. To analyze the effects of uncertainties in transit networks that may be caused by probabilistic travel demand, congestion, or vehicle frequencies, th...

The non-additive traffic equilibrium problem (NaTEP) overcomes the inadequacies of the additivity assumption in traditional traffic equilibrium models by relaxing the cost incurred on each path that is not a simple sum of the link costs on that path. The computation of the NaTEP heavily depends on the efficiency of the step size determination. This...

Static pricing is currently the most prevalent form of congestion pricing. Most existing methods for static pricing design use equilibrium-based indices as the optimization objective function. However, in reality, the equilibrium may not be reached within the toll planning horizon, and thus equilibrium-based pricing schemes might be ineffective in...

Modeling bicycle traffic assignment requires consideration of the various factors and criteria that could play a role in a cyclist’s route decision‐making process. However, existing studies on bicycle route choice analysis tend to overlook the less tangible or measurable aspects of cyclist route decision‐making, such as a cyclist’s cognitive unders...

In this paper, we develop a new tool to enhance the resilience of transportation networks by optimizing route diversity redundancy from travelers’ perspective. The decision of where to add new links is made to generate as many origin–destination (O-D) pairs with alternative distinct routes as possible to potentially alleviate the impact of disrupti...

This study investigates the impacts of the least perceived travel cost on the stochastic user equilibrium (SUE) problem. The Weibit SUE models are considered since they have a location parameter that naturally capture the least perceived travel cost. Considering a positive location parameter enhances the behavioral reality by attaching a positive l...

Freight transportation network is an essential backbone for supporting the industrial activities and economic developments of the nation and global trade. In this paper, we extend the network-based measures recently developed by Xu et al. (2018) for assessing freight transportation network redundancy – an important component in making freight trans...

The disruption of critical components in a transportation network can bring about severe network performance degradation and requires a relatively long period to recover, which would lead to commuters’ day-to-day route choice adjustment. Under disruptions, there would be greater travel time variability (objective uncertainty) and travelers’ percept...

A verified behavior assumption for travelers faced with travel time variability is that beyond the mean travel time, travelers will add a travel time margin to mitigate the probability of being late. Compared with the most widely used standard deviation and variance in the VOR studies, travel time margin is the additional travel time reserved by tr...

In recent years, a multiplicative hybrid (MH) route choice model was proposed to overcome the drawbacks of the multinomial logit (MNL) model and the multinomial weibit (MNW) model. This paper compares the conditions for the stochastic traffic assignment paradox of the three models. We analyze the condition when improving a link in an uncongested ne...

The number of efficient paths between an origin-destination (O-D) pair provides the route diversity degree of possibly used paths in a transportation network, and it has many important applications in practice, e.g., network redundancy assessment, network sensor location problem, and vulnerable link/node identification problem. The existing countin...

This study provides a gradient projection (GP) algorithm to solve the combined modal split and traffic assignment (CMSTA) problem. The nested logit (NL) model is used to consider the mode correlation under the user equilibrium (UE) route choice condition. Specifically, a two-phase GP algorithm is developed to handle the hierarchical structure of th...

The mixed itinerary-size weibit (MISW) model was recently developed for predicting passengers’ itinerary-choice behaviors in a schedule-based railway network. It considers passengers’ heterogeneous perceptions and relaxes the independently and identically distributed assumptions of random utility models. However, this model has not been verified us...

Automated Electric Transportation (AET) is an innovative concept that aims to integrate energy, vehicle, highway, and communication infrastructures. It provides an electrified transportation system to support in-motion energy transfer through wireless charging of inductive coupling in the highway. A considerable body of previous research has sought...

The COVID-19 outbreak has necessitated a critical review of urban transportation and its role in society against the backdrop of an exogenous shock. This article extends the transportation literature regarding community responses to the COVID-19 pandemic and what lessons can be obtained from the case of Hong Kong in 2020. Individual behavior and co...

Better transportation and medical service systems contribute to urban sustainable development. Dock-less bike-sharing system (DLBS) is an innovative, sustainable, and flexible travel mode that has been a worldwide spread. This paper addresses a pioneer research aims to explore the characteristics of DLBS usage in outpatient trips and its impacts on...

Many studies have evaluated the influence of the built environment on public transport. Some studies assign subjective weights to environmental factors, which could oversimplify spatial heterogeneity and overlook the temporal dimension. On the other hand, the spatial-interaction network of public transport system is seldom considered. In this paper...

The Mass Transit Railway (MTR) serves as the backbone of the Hong Kong public transportation network and continues to be expanded in phases. Nevertheless, occasional but severe disruptions have raised concerns about whether the proposed MTR expansions will benefit the system resilience. To assess the value of each stage of MTR network expansion, it...

This paper aims to fill the research gap of the relationship between the access travel time (ATT) estimation and the accessibility to high speed railway (HSR) station. A regression analysis was developed on the basis of risk-return model to analyze the access travel time estimation error (ATTEE). The data sources were 1595 valid interview survey da...

Step size determination (also known as line search) is an important component in effective algorithmic development for solving the traffic assignment problem. In this paper, we explore a novel step size determination scheme, the Barzilai-Borwein (BB) step size, and adapt it for solving the stochastic user equilibrium (SUE) problem. The BB step size...

Current air traffic control (ATC) procedures sequence aircraft arrivals in the First Come First Serve (FCFS) order which is more suitable for low traffic intensity aerodrome. For higher traffic intensity aerodrome, the FCFS method could be inefficient orders since it requires a longer horizontal minimum separation between two following aircrafts. T...

Cycling is gaining popularity both as a mode of travel in urban communities and as an alternative mode to private motorized vehicles due to its wide range of benefits (health, environmental, and economical). However, this change in modal share is not reflected in current transportation planning and travel demand forecasting modeling processes. The...

In this paper, we consider captive mode travelers (those who have no other choices but rely on one specific travel mode for daily commuting trips) in a multi-modal network equilibrium (MMNE) problem. Specifically, the dogit model is adopted to account for captive mode travelers in the modal split problem, and the path-size logit (PSL) model is used...

The aggregated traffic flow forecasting problem with multi-level mixed logit based route choice model is discussed in this paper. Multi-level unobserved taste heterogeneity in route choice is further divided to two parts, the OD pair specific and observation specific. With the proposed model, the observations between the same OD pair, as well as th...

This study proposes a new household optimum (HO) utility approach to model the intra-household interactions between household members by heterogeneous household type with different size in deciding their daily joint/solo activities and travel in congested road networks. In contrast to the conventional approach based on selfish choices of individual...

In this study, we propose a new schedule-based itinerary-choice model, the mixed itinerary-size weibit model, to address the independently and identically distributed assumptions that are typically used in random utility models and heterogeneity of passengers’ perceptions. Specifically, the Weibull distributed random error term resolves the percept...

This paper demonstrates a counter-intuitive phenomenon that “paradox links” (i.e. marginally improving or adding these links will increase a system’s cost) can sometimes decrease a system’s cost. It can be expressed that simultaneously improving paradox link to a certain threshold (rather than only marginal improvement) or adding more paradox links...

We review recent studies on transportation network performance under perturbations. Three representative concepts relating to network performance are covered: reliability, vulnerability, and resilience. With an overview of the definitions and the quantitative indices of these three concepts, we analyse and compare their similarities and differences...

Railway network is an integral part of the economy of many countries. Identifying critical network elements can help network executives to take appropriate preventive actions before the occurrence of catastrophic disruptions or to add necessary redundancy to enhance the resilience of the rail network. The criticality of an element or a link is meas...

It is necessary to design and evaluate the effectiveness of walking facilities to accommodate the needs of all pedestrian groups, including individuals with disabilities. The Americans with Disability Act (ADA) standard requires that each facility or part of a facility constructed by, on behalf of, or for the use of a public entity shall be designe...

Currently, there is a growing movement in the urban planning and transportation sectors advocating for the creation of sustainable and livable communities. Since these communities focus on the promotion of public health and the protection of environmental resources, it comes to no surprise that cycling is experiencing increasing popularity as an al...

Accessibility is an important link between transportation and land use. As a typical measure of accessibility, logsum or a utility-based measure has been widely used in project appraisal, urban transit accessibility evaluation, destination choice, and network vulnerability analysis. Since the logsum term is the log of the denominator of the choice...

Travel time reliability (TTR) has received great attention in the past decades. The majority of TTR measures rely on the travel time percentile function as a basic element for performance evaluation. There are two main approaches for deriving the travel time percentile function: simple unimodal probability distribution models and mixture/nonparamet...

This paper examines the optimal location and allocation of relief trains (RTs) to enhance the resilience level of the rail network. Unlike probabilistic approaches, the priority of demand is handled by link exposure measure which considers the operational attributes of links and accessibility to road system. We formulate the proposed model using a...

There is a need to model individuals with physical disabilities in a crowd. This requires both understanding how such individuals impact a crowd and how the crowd impacts them. Previous efforts have adjusted velocity to represent individuals with disabilities in a crowd. The various disabilities that are represented in a crowd of individuals show m...

The primary goal of this study is to identify those factors that influence public transportation (PT) competitiveness through an analysis of current passenger loyalty. To accomplish this goal, a structural equation model (SEM) is introduced to construct the theoretical model. A comprehensive set of hypotheses is tested to explore the relationships...

This paper analyses the effects of congestion and stochastic perceived error in stochastic traffic assignment paradox, by the measure of both actual and perceived travel cost. Two different circumstances are studied: improving an existing link and adding a new link. It is found that different congestion cost functions and perceived error levels wil...

Empirical studies have revealed that travel time variability (TTV) can significantly affect travelers’ behaviors and planners’ cost-benefit assessment of transportation projects. It is therefore important to systematically quantify the value of TTV (VTTV) and its impact. Recently, Fosgerau's valuation method makes this quantification possible by co...

Pedestrian evacuation studies are critical in obtaining information about evacuation scenarios and in preparing to face the challenges of actual evacuations. Studies have examined evacuation policies, exit choice modeling, and evacuation curve analysis. Some studies have addressed the evacuation behavior of individuals with disabilities (IWDs), alt...

Cycling has been considered as a healthy, environmentally friendly, and economical alternative mode of travel to motorized vehicles (especially private motorized vehicles). However, bicycles have often been neglected in the transportation planning and travel demand forecasting modeling processes. The current practice in modeling bicycle trips in a...

Poster at TRB-863-Behavioral Route Choice

863-Behavioral Route Choice

Due to the increasing energy prices and environmental issues, energy conservation for metro trains has become an important research topic in recent years. The static timetable optimization approach can reduce the trains’ energy consumption to a certain degree by scheduling multiple trains’ movements. However, this optimization approach is prone to...

This paper aims to develop an optimization approach for deriving the upper and lower bounds of transportation network vulnerability under simultaneous disruptions of multiple links without the need to evaluate all possible combinations as in the enumerative approach. Mathematically, we formulate the upper and lower bounds of network vulnerability a...

Select link analysis provides information of where traffic comes from and goes to at selected links. This disaggregate information has wide applications in practice. The state-of-the-art planning software packages often adopt the user equilibrium (UE) model for select link analysis. However, empirical studies have repeatedly revealed that the stoch...

This paper aims to develop an optimization approach for deriving the upper and lower bounds of transportation network vulnerability under simultaneous disruptions of multiple links without the need to evaluate all possible combinations as in the enumerative approach. Mathematically, we formulate the upper and lower bounds of network vulnerability a...

It is imperative to design walking facility infrastructures to accommodate the needs of all pedestrian, including individuals with disabilities. Unfortunately, individuals with disabilities are often overlooked due to the lack of available data. The purpose of this study was to measure the individual pedestrian walking behaviors of individuals with...

In this paper, we propose a methodology to analyze the most critical links of a railway network based on flow interdiction. Our strategy for network interdiction is to maximize network disruption by removing the links with the greatest impact to the system. For this purpose, we first introduce our primary model to determine vulnerable links based o...

Reduction of vehicle emissions is a major component of sustainable transportation development. The promotion of green transport modes is a worthwhile and sustainable approach to change transport mode shares and to contribute to healthier travel choices. In this paper, we provide an alternate weibit-based model for the combined modal split and traff...

This paper proposes a new modeling approach for network-wide on-line travel time estimation with inconsistent data from multiple sensor systems. With the development of Intelligent Transportation Systems (ITS), travel time can be estimated on some links or path segments in transportation networks by a variety of sensor systems. One limitation of mo...

Metro is considered as an efficient transport mode to alleviate traffic congestion in big cities because of its large transport capacity. Generally, a good metro system means not only a passenger-oriented timetable but also an eco-friendly speed profile. This study develops a bi-objective nonlinear programming model to determine the optimal timetab...

Road speed limits have been widely implemented in many countries to improve traffic safety and environmental quality. In this paper, we provide a different perspective on the network-wide impacts of speed limits: managing network uncertainty. Specifically, a multi-dimensional modeling approach is proposed to investigate the impacts of speed limits...