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Publications (80)
We consider a bottleneck system in a state of disequilibrium, in which commuters are heterogeneous in the values of travel time and schedule delays. Three representative dynamical systems are used to formulate the day-to-day departure time choice of commuters, and a Walrasian toll charge scheme is utilized to control the evolutionary process of tra...
Suitable information of routes and exits can help guide evacuees to approach the expected destinations more efficiently in case of emergencies, such as fire accidents, terrorist attacks and power failures. Therefore, the purpose of this paper is to provide an overview of the dynamics of two patterns of guided crowd evacuation. One is source-guided...
One of the critical challenges in the development of pedestrian models is the lack of relevant data under emergency conditions. In this paper, we reveal several behavior characteristics of passenger emergency evacuation from a burning bus carriage through observing and analyzing a video recording, attempting to close the gap between practical obser...
We propose a dynamical system model to formulate the day-to-day dynamics of both traveler mode choice and ride-sourcing car supply in a duopoly ride-sourcing market. In the transport system, besides usual transport modes, e.g., private car and public transit, there are two platforms to provide ride-sourcing services, and travelers choose travel mod...
This paper extends the work of Zhang et al. (2008) to investigate the daily commuting patterns allowing both late arrival in the morning and early departure in the evening in a linear city. Given the fixed parking locations of morning commuters, the Nash equilibrium principle is employed to formulate commuters’ departure time choice in the evening...
We investigate the route choice behavior of pedestrians under the condition of local view by using a field observation in a subway station and a microscopic pedestrian model with discrete space representation. The local view of a pedestrian means that the pedestrian's field of vision can be blocked by obstacles. Several typical phenomena with respe...
This paper presents an extended cell transmission model to simulate an emergency evacuation of crowd in a supermarket scenario. The supermarket scenario with a daily shopping, an emergency exit and multiple parallel shelves is discretized into a set of regular hexagonal cells. First, we verify the validity of the model by comparing the results of t...
In this paper, we propose a microscopic pedestrian model with discrete space representation to simulate pedestrian flows through multiple queues. In the model, two types of pedestrians, i.e., passing pedestrians and queuing pedestrians, are involved and they can intersect in different angles. Both the interaction and movement of pedestrians are joi...
We analyze the commuting patterns and parking modes for integrated daily commuting under different regimes. Based on a bi-direction bottleneck network with a spatial pattern of parking, the daily commuting patterns with parking location choices are analyzed. Without road toll and parking fee, there exist two equilibrium flow patterns and one parkin...
This paper studies the impact of route choice set of networks on the day-to-day traffic dynamics through conducting a group of experiments, in which four traffic networks with different sets for choice are used. It is observed that a deterministic user equilibrium (DUE) state is difficult to sustain and the probability of reaching DUE is larger in...
We concern the modal choice of commuters in a transport system comprising a highway, which is only used by autos, in parallel to two separate transit lines, which are only used by buses. For the operation of the transit lines, two market structures are considered: monopolistic and duopolistic. Each transit operator sets its transit fare to maximize...
In this study, we conducted a series of experiments to investigate child behavior during self-evacuation and guided evacuation under non-emergency and emergency situations. The properties of child flow dynamics are obtained through analysis of the experimental video recordings. It is found that under a non-emergency situation, the evacuation proces...
Fraud detection is usually compared to finding a needle in a haystack and remains a challenging task because fraudulent acts are buried in massive amounts of normal behavior and true intentions may be disguised in a single snapshot. Indeed, fraudulent incidents usually take place in consecutive time steps to gain illegal benefits, which provides un...
Climate change is posing risks for human and natural systems, and one of the most important questions faced by policy makers is to reduce such risks and impacts through adaption and mitigation actions. As the country with the highest CO2 emissions, China is facing unprecedented challenges: climate change, energy structure transformation and socio-e...
We propose an extended cell transmission model with regular hexagonal cell representation to simulate the bi-directional pedestrian flow through a bottleneck. We take humility behavior among pedestrians into the model as a set of parameters. Without loss of generality, this model simulates the boarding and alighting process of passengers for a spec...
We concern the modal choice of commuters in a transport system comprising a highway, which is only used by autos, in parallel to a transit line, which is only used by buses. In the transport system, the in-vehicle congestion of passengers in bus carriages is treated as a negative externality cost of affecting the modal choice of commuters and commu...
In this paper, a cellular automata model for pedestrian evacuation is presented. Special attention is paid to a phenomenon wherein an artificial and allegedly unrealistic bias in route choice is introduced. This phenomenon is caused by the so-called gray areas that affect the calculation of the potential fields which dictate pedestrians’ movements...
We propose a dynamic tradable credit scheme for control of the day-to-day evolution process of traffic flows towards the system optimum (SO) state in a traffic network with elastic demand. In the scheme, the distribution and charge of travel credits are adjusted from period to period. The interacting dynamics among day-to-day traffic flows, period-...
This paper investigates the impact of travel-time uncertainty on day-to-day route choices of travelers by using a set of laboratory experiments and statistical analytical methods. A route choice experiment with 30 participants was conducted and performed 30 times at five different travel-time-uncertainty levels. The uncertainty of travel time depen...
Bus holding is a widely used control method to regularize bus headways and reduce bus bunching. The method works in such a way by delaying buses at control points if their departure times or headways deviate from the planned ones. However, it may result in reduced bus commercial speeds and increased passenger onboard travel time. To avoid this prob...
We developed a data-driven approach for extracting and analyzing the interagent and intergroup collaboration patterns centered on the COLLSTRUC language and its related algorithm. The proposed approach is evaluated by comparing it with existing studies related to collaboration patterns and through an empirical evaluation using Volvo IT event logs.
In the operational planning process of public transport, the time a passenger spends on waiting is a very critical element for judging passenger service. Schedule synchronization is a useful strategy for reducing bus waiting time and improving service connectivity. This paper develops an extended vehicle scheduling model, taking into account the in...
The aim of this study is to address the following issues: 1) revealing the typical behaviors and properties of pedestrian movement when going upstairs and downstairs; 2) constructing a pedestrian evacuation model to formulate the walking process of pedestrians in stair area; 3) verifying that the cell transmission model widely used in the two-dimen...
Child behavior during evacuation, as a critical problem that has not been fully explored and understood, is investigated in this paper, through conducting a group of experiments and developing a cellular automaton (CA) model. The video recordings have revealed several typical patterns of child behavior related to distance, obstacle and congestion l...
The efficacy of the principal–agent contract in supply-chain quality control depends not only on contract parameters but also such noncontract parameters as cost of a high-quality effort and the diagnostic error of the inspection policy. The noncontract parameters usually fluctuate and are unobservable during contract execution, which may hinder su...
This study proposes a potential-based dynamic pedestrian flow assignment model to optimize the evacuation time needed for all pedestrians to leave an indoor or outdoor area with internal obstacles and multiple exits, e.g., railway station, air terminal, plaza, and park. In the model, the dynamic loading of pedestrian flows on a two-dimensional spac...
An extended cell transmission model is proposed to simulate bi-directional pedestrian flow in the corridor. In the model, the walking space is discretized into regular hexagonal cells. Three walking preferences of pedestrians are taken into account, including walking on the right-hand side, following front people in the same direction, and avoiding...
An improved bi-directional pedestrian model based on reciprocal velocity obstacles (RVO) is proposed to investigate self-organization phenomena for bi-directional pedestrian flows crossing bottlenecks, and the influencing factors of pedestrian flow are analyzed. According to the RVO model problem, an improved method is constructed. The model of bi-...
We investigate the day-to-day modal choice of commuters in a bi-modal transportation system comprising both private transport and public transit. On each day, commuters adjust their modal choice, based on the previous day's perceived travel cost and intraday toll or subsidy of each mode, to minimize their perceived travel cost. Meanwhile, the trans...
This paper investigated the optimal deployment problem of electric vehicle lanes to maximize the utilization of electric vehicles in the future. By considering charging demands and driving limitation of electric vehicles, which are obviously distinguishable from gasoline-powered vehicles, a bi-level programing model was presented to solve the propo...
This paper investigates the problem of locating public charging stations for electric vehicles in an urban traffic network. To equilibrate the choice of battery recharging or swapping for electric vehicles without running out of charge, as well as to reduce the construction cost of public charging stations, a bi-level programing model of locating p...
The dynamic traffic equilibrium problem has been a pivotal area of research in transportation for a few decades. The current state-of-the-art research in this area generally considers simultaneous departure time and route choice. In this paper, we theoretically prove that, in the simplest standard bottleneck model with a sufficient number of commut...
We extend the proportional swap system by Smith (1984a) and the network tatonnement process by Friesz et al. (1994) to formulate the day-to-day evolution of departure time choice under bounded rationality in the bottleneck model. It is shown that the stationary points of the doubly dynamical systems exist and are equivalent to the boundedly rationa...
We extend the proportional swap system by Smith (1984a) and the network tatonnement process by Friesz et al. (1994) to formulate the day-to-day evolution of departure time choice under bounded rationality in the bottleneck model. It is shown that the stationary points of the doubly dynamical systems exist and are equivalent to the boundedly rationa...
Through relaxing the behavior assumption adopted in Smith's model (Smith, 1984), we propose a discrete dynamical system to formulate the day-to-day evolution process of traffic flows from a non-equilibrium state to an equilibrium state. Depending on certain preconditions, the equilibrium state can be equivalent to a Wardrop user equilibrium (UE), L...
Delays of both pedestrians, who are classified according to whether complying with traffic law, and vehicles at a signalized crosswalk are analyzed in this paper. The truncated Adams’ model is applied to generate the probability and mean of delay of pedestrians non-complying with traffic law. Using the section-based traffic queuing-theory and the s...
This work presents a second-order predictive dynamic model for pedestrian flow to investigate movement patterns and non-equilibrium phenomena in pedestrian traffic. This model is described as a system of nonlinear hyperbolic conservation laws with relaxation under the hypothesis that a group of pedestrians are regarded as a continuous anisotropic m...
We propose a dynamical system model to formulate day-to-day traffic assignment. This model describes the dynamic adjustment process of route flows from day to day and its stationary state is equivalent to the Logit stochastic user equilibrium state. We also analyze several properties of the model, including the equivalence between the stationary st...
This paper investigates evolutionary implementation of congestion pricing schemes to minimize the system cost and time, measured in monetary and time units, respectively, with the travelers' day-to-day route adjustment behavior and their heterogeneity. The travelers' heterogeneity is captured by their value-of-times. First, the multi-class flow dyn...
The left-turn of vehicles at intersections has significant impacts on urban traffic congestions and accidents, which have negative effect on vehicle emissions causing air pollution. Many urban traffic networks prohibit direct left-turns for transport planning to keep traffic moving efficiently on major roads. As such, this paper proposes a bi-level...
A bi-objective programming model (BP) with spatial equity constraints is proposed to site park-and-ride (P&R) facilities in traffic networks. Both the number and locations of P&R facilities are determined. The maximal coverage and minimal resource utilization criteria, which are generally conflicting, are simultaneously considered to reveal the tra...
For a predetermined set of an upper bound of link flows, this paper proposes a price-based congestion control scheme for achieving such a restraint target of traffic flow that evolves from day to day. On each day, drivers have to pay a toll selected from a feasible set. The tolls on each day are determined by the link flows and toll charges on the...
We propose a revised social force model to simulate the pedestrian counter flow through a bottleneck. Spatial and temporal separation rules are involved in this model so as to reproduce these self-organizing movement patterns of pedestrians, including oscillatory flow and three classes of lane formations. Moreover, by scenario simulations, we show...
This paper investigates the Pareto efficiency of the various reliability-based traffic equilibria proposed in the literature and the risk-taking behavior of travelers. Reliability indexes such as the percentile travel time (PTT), travel time budget (TTB), mean excess travel time (METT) and the quadratic disutility function (QDF) are examined in ter...
We develop a cellular automata model with finer discretization of space and higher walking velocities more than one cell. The model is used to simulate the evacuation process of pedestrians from a room with an exit. By simulation experiments, we find subtle effects of the discretization degree and walking velocities on the shape of the crowd near t...
A discrete dynamical system model, called a discrete rational adjustment process (DRAP), is built upon link-based variables to characterize the process of achieving equilibrium from a non-equilibrium state in traffic networks. The equilibrium state can be in either a deterministic or a stochastic user equilibrium state. The DRAP is formulated in a...
A microscopic pedestrian model based on cellular automata is proposed and three groups of experiments on pedestrian evacuation from a double-exit room are conducted to investigate the route choice of pedestrians during evacuation. In the model, the route-choice behavior of pedestrians is affected by the route distance from the pedestrians to the ex...
This study proposes a potential field algorithm for formulating pedestrian route choice behavior during evacuation in individual-based models with discrete space representation. The potential field reflects the effect of the route distance, pedestrian congestion and route capacity on route choice. Numerical simulations show that the developed model...
When the microscopic pedestrian models, in which pedestrian space is continuously represented, are used to simulate pedestrian movement in the buildings with internal obstacles, some issues arise and need be dealt with in detail. This paper discusses two of the issues, namely formulating the desired direction of each pedestrian in the buildings and...
We study a class of pedestrian evacuation process in rooms without visibility by analytical and simulative methods. First, the moving distance of pedestrians for leaving the rooms is analyzed using the mean and variance theory. A microscopic pedestrian model is then extended to simulate pedestrian evacuation in the rooms. By numerical examples, the...
The route choice of pedestrians during evacuation under conditions of both good and zero visibility is investigated using a group of experiments conducted in a classroom, and a microscopic pedestrian model with discrete space representation. Observation of the video recordings made during the experiments reveals several typical forms of behavior re...
Using the sample data obtained from a group of pedestrian experiments, a function formulating the velocity-density relationship of pedestrians and linear regression is proposed to provide empirical evidence for the look-ahead behavior of pedestrians in bi-directional flows. We find that the velocity of pedestrians is negatively correlated with not...
In this paper, a microscopic pedestrian model is developed for simulating pedestrian flow through walkways with not only perpendicular corners. These developments mainly include the determination of desired direction of pedestrians in the walkways, the action of pedestrians encountering walls around corner, and the generation of pedestrians in the...
We propose a pedestrian position update rule, which is added to a microscopic pedestrian model to avoid pedestrian overlap. In the rule, the step size of a pedestrian moving in a selected direction at each update is in inverse proportion to the repulsive actions imposed by other pedestrians moving in a direction with an exponential rate. The positi...
The crossing of vehicle flow by pedestrians at either signalized crosswalks or locations away from crosswalks is studied using a car-following model. The model process is constructed, and two safe criterions deciding whether pedestrians begin to cross a road and a rule stopping vehicles at a signal intersection are proposed. Numerical results indic...
When the car-following model is used to formulate vehicle flows crossed by pedestrians at random different locations on roads, some issues arising need be dealt with in detail. This paper discusses several of these issues, including the model process, the safe criterion, the influence of pedestrian crossing on the acceleration, velocity and displac...
A method for formulating the route choice behavior of pedestrians in evacuation in closed areas with internal obstacles is proposed. The method is implemented in a pedestrian model, in which the route choice is determined by the potential of discrete space. The potential measures the total effect of such factors affecting route choice as route dist...
We present a method of predicting pedestrian route choice behavior and physical congestion during the evacuation of indoor areas with internal obstacles. Under the proposed method, a network is first constructed by discretizing the space into regular hexagonal cells and giving these cells potentials before a modified cell transmission model is empl...
The rule of updating pedestrian position in a microscopic pedestrian model is substituted by a proposed new rule. In the new rule, the step size of a pedestrian moving in a selected direction at each update is in inverse proportion to repulsive actions imposed by other ones in the direction at an exponential rate, and also pedestrian positions are...
We develop a method to formulate pedestrians' route choice behavior and physical congestion during evacuation process in indoor areas with internal obstacles. This method first constructs a network through discretizing the pedestrian space and then employs a proposed cell transmission model to predict the pedestrian flow's evolution propagation ove...
A logit-based discrete choice model is proposed to study the exit choice behaviour of evacuees in rooms with internal obstacles and multiple exits. Several factors influencing the exit choice behaviour, including the information obtained by evacuees, the tendency of following others, the visibility and familiarity of exits and the physical conditio...
We develop a microscopic pedestrian-simulation model in which pedestrian positions are updated at discrete time steps. At each time step, each pedestrian probabilistically selects a direction of movement from a predetermined set according to a logit-type function that considers the dynamics of other pedestrians around, and then selects a step size...
Considering such a fact that the traffic demands freshly entering a network do not have perfect information about traffic condition and may then choose routes randomly, in this paper, we present an improved network traffic flow evolution model. The model’s properties and fixed points are investigated. Numerical results obtained from a grid network...
Considering such a fact that the traffic demand freshly entering a network does not have perfect information about traffic condition and then might choose travel routes randomly, we propose an improved network traffic flow evolution model in this article. The model's properties and fixed points are investigated. The fixed points of the model, which...
A modified floor field model is proposed to simulate pedestrian evacuation in rooms with internal obstacles and multiple exits. The modifications lie in developing a method to calculate the static floor field for every lattice site, which is determined by the most feasible distance to an exit, and employing a logit-based discrete choice principle t...
In order to formulate the process of realizing stochastic user equilibrium, authors proposed an evolution model of multiclass and multicriteria stochastic equilibrium traffic assignment. In the model, all travelers in a traffic network were discredited into finite number of classes according to their values of time and each class was divided into t...
Considering the fact that the interaction among pedestrians in a high-density crowd is asymmetric, accumulative and transferable, we present a modified floor field cellular automata model for simulating the pedestrian evacuation. In this model, the space for evacuation is discretized into smaller cells, every pedestrian is allowed to occupy multipl...
Considering such a fact that travellers dynamically adjust their routes and the resultant link traffic flows in a network evolve over time, this paper proposes a dynamical evolutionary model of the traffic assignment problem with endogenous origin---destination (OD) demands. The model's stability is analysed and the resultant user equilibrium (UE)...
We present a mobile lattice gas model for simulating the pedestrian evacuation process in a public building, through combining the advantages of the lattice gas model and the social force model. In our model, the interaction force between every two pedestrians and that between a pedestrian and the building wall are determined by the distance and th...
This paper presents a joint optimization model of congested road-use pricing and capacity using the optimal control theory in disequilibrium traffic networks with elastic demand. The model aims at maximizing the total network benefit from travel within the study horizon. Referring to the discrete version of the model, the first-order optimality con...
