Urban Taxi Services Research Articles

Trajectory-based clustering for enhanced attractive region mining in urban taxi services

ABSTRACT Trajectory data, increasingly available due to location tracking technologies, holds immense potential for intelligent traffic management and urban planning. Traditional 'attractive region' mining methods often rely on density-based clustering, neglecting the inherent path information within trajectories. To address this, we propose a novel graph-based approach for attractive region discovery. By transforming trajectory data into graphs, we effectively leverage path and connectivity information for clustering with locality-sensitive hashing. Our study introduces the pARM, pgARM, and hgARM algorithms, demonstrating their superiority over GridDBScan through experiments on real-world datasets. We employ Davies–Bouldin metric and visualization techniques to highlight the robustness of our approach, especially for datasets with varied degree distributions. Although our method may have slightly longer processing times for smaller grid sizes, it achieves execution times comparable to GridDBScan for larger grids. We rigorously analyze performance variations within our algorithms using execution time, clustering coefficient, and modularity scores, providing guidance for their optimal application.

The trend of the structural change of the city taxi market in China: a modal split analysis in the context of different market access rules

ABSTRACT To elucidate the impact of online car-hailing (OCH) on traditional taxi services and in producing structural changes to urban taxi markets in China, we propose a model based on the market access rules and business models of the two modes that analyzes their interactions in the following arenas: fleet size, passenger waiting time, service level, and driver income. Then, we build a nested logit model to predict the modal splits and market shares for four travel modes (online car-hailing, traditional taxi, metro, and bus). Taking Ningbo as an example, we estimate the changes in the number of OCH vehicles, the modal splits of the four travel modes, and the new equilibrium in urban taxi service markets. We show that OCH puts significant pressure on the traditional taxi market due to the positive feedback between OCH fleet size and its service quality.

A SYSTEM DYNAMICS MODEL FOR URBAN TAXI PRICE SIMULATION

Urban taxi services have been developing year on year, playing an increasingly important role in the economy and the transportation markets of each city. This increases interest in measuring their performance. This paper analysed the relationship among the four stakeholders (including administrative department, operational companies, taxi drivers and customers) for urban taxi passenger transport system in China, and applied System Dynamics (SD) model to explore the dynamic characteristics of urban taxi price system. The main achievements of this paper are as follows, firstly, this paper adopted stakeholder mapping to describe the relationships among the four stakeholders. Then analysed the causal flow diagrams and the different variables of urban taxi passenger transport system operation, and presented the SD model, which considers factors that affect the taxi operation. With the combination of taxi operation data of Harbin city, we simulated eleven urban taxi operation scenarios and proposed kinds of suggestions to improve urban taxi passenger transport system operation, which can provide a good basis for recommending policy decisions for urban taxi market.

Assessment of Intra Urban Taxi Services in Ilorin West Local Government Area

Assessment of Intra Urban Taxi Services in Ilorin West Local Government Area

Modeling urban taxi services with e-hailings: A queueing network approach

The rise of e-hailing taxis has significantly altered urban transportation system and led to a competitive taxi market with both traditional street-hailing and e-hailing taxis. The various taxi services provide similar door-to-door rides, thus compete with each other. Meanwhile, the expanding fleet size of e-hailing taxis, together with considerable number of traditional taxicabs, influence the urban road network performance, which can also in turn affect taxi mode choice and operation. In this study, we propose an innovative modeling structure for the competitive taxi market and capture the interactions not only within the taxi market but also between the taxi market and urban road system.The model is built on a network linking a certain number of queues, derived from both the taxi and urban road system. Considering both the passenger and vehicle arrivals, we utilize an assembly-like queue SM/M/1 for passenger-vehicle matching within the taxi system, which controls how many and how frequently vehicles drive from the taxi system to the urban road system. A common multi-server M/M/c queue that can account for road capacity is proposed for the urban road system and a feedback of network states is sent back to the taxi system. Then the stationary state distributions, as well as asymptotic properties, of the queueing network are discussed.An example is designed based on data from New York City. Numerical results show that the proposed modeling structure, together with the corresponding approximation method, can capture dynamics within high demand areas and, in particular, a spatially balanced system. Overall, this study shows how the queueing network approach can measure aggregated performance of various taxi services, for instance, not only the waiting/searching time during passenger-vehicle matching but also the delays in the urban road network. Furthermore, the model can be generalized to study the control and management of taxi markets.

An alternative methodology for evaluating the service quality of urban taxis

This paper proposes an alternative methodology to evaluate the service quality of urban taxis and develops a level-of-service (LOS) standard for taxi customers to monitor performance. A customer satisfaction survey was conducted from January to March 2013 in Hong Kong, with the respondents invited to give specific satisfaction ratings for ten service aspects individually and a global satisfaction rating for the overall taxi service quality, as well as to rank the important aspects that influence the given global rating. The ten service aspects related to the amount of time consumed when taking taxis, services and facilities provided for finding taxis, internal environments of taxis, and personal services provided by taxi drivers. An enhanced linear regression model was developed to identify the priority areas for improvement of urban taxi service quality. Based on the numerical score of overall taxi service quality, a six-level LOS standard, similar to academic grading, is introduced accordingly to improve the general public's understanding of the current service level. This paper discusses the potential policy implications to enhance the taxi service quality in Hong Kong, which can be applied to other metropolitan cities that provide similar urban taxi services.

The impact of rainfall on the temporal and spatial distribution of taxi passengers.

This paper focuses on the impact of rainfall on the temporal and spatial distribution of taxi passengers. The main objective is to provide guidance for taxi scheduling on rainy days. To this end, we take the occupied and empty states of taxis as units of analysis. By matching a taxi's GPS data to its taximeter data, we can obtain the taxi's operational time and the taxi driver's income from every unit of analysis. The ratio of taxi operation time to taxi drivers' income is used to measure the quality of taxi passengers. The research results show that the spatio-temporal evolution of urban taxi service demand differs based on rainfall conditions and hours of operation. During non-rush hours, taxi demand in peripheral areas is significantly reduced under increasing precipitation conditions, whereas during rush hours, the demand for highly profitable taxi services steadily increases. Thus, as an intelligent response for taxi operations and dispatching, taxi services should guide cruising taxis to high-demand regions to increase their service time and ride opportunities.

Zoox Self-Driving Startup to Design, Build, Operate Its Own Urban Taxi Service

Zoox Self-Driving Startup to Design, Build, Operate Its Own Urban Taxi Service

A Graph-Based Approach to Measuring the Efficiency of an Urban Taxi Service System

Taxi service systems in big cities are immensely complex due to the interaction and self-organization between taxi drivers and passengers. An inefficient taxi service system leads to more empty trips for drivers and longer waiting time for passengers and introduces unnecessary congestion on the road network. In this paper, we investigate the efficiency level of the taxi service system using real-world large-scale taxi trip data. By assuming a hypothetical system-wide recommendation system, two approaches are proposed to find the theoretical optimal strategies that minimize the cost of empty trips and the number of taxis required to satisfy all the observed trips. The optimization problems are transformed into equivalent graph problems and solved using polynomial time algorithms. The taxi trip data in New York City are used to quantitatively examine the gap between the current system performance and the theoretically optimal system. The numerical results indicate that, if system-wide information between taxi drivers and passengers was shared, it is possible to reduce 60%–90% of the total empty trip cost depending on different objectives, and one-third of all taxis required to serve all observed trips. The existence of destructive competition among taxi drivers is also uncovered in the actual taxi service system. The huge performance gap suggests an urgent need for a system reconsideration in designing taxi recommendation systems.

Aggregated Modeling of Urban Taxi Services

Models are an indispensable tool for decision makers when defining the principal policy measures of the taxi services, such as fleet size, fares or operational modes of the services within the city. Various models have been developed for calculating the variables that characterize the taxi services in urban regions. This paper presents an extensive review of the presented formulations for the modeling of taxi services in urban areas. The variables of the problem are identified and analyzed, presenting the different formulations proposed in the literature for each one of the three operational modes (hailing, stand and dispatching).

Taxi Bidirectional Search System Based on Smart Phone

For the issues of unreasonable taxi distribution, high load rate and low dispatching efficiency etc. in the current city calling taxi services, the paper presents some key technologies of implementation of taxi driver-passenger bidirectional search system based on smart phones, including map matching, hotspot analysis, taxi route planning and bidirectional search UI. The results help achieve efficiency of urban taxi service.

Returns to scale in the production of taxi services: an empirical analysis

This paper applies a log-linear simultaneous equation model to estimate the returns to scale in a Cobb–Douglas-type bilateral searching and meeting function which characterises the search frictions between taxis and customers. Number of taxis, taxi fare, population, average occupied taxi journey time and disposable income are used as exogenous variables; customer demand, average customer waiting time and average taxi waiting and cruising time in search of each customer are used as endogenous variables. These variables are coupled together through the simultaneous equation model whose parameters are estimated from the Hong Kong Annual Taxi Survey data as well as data from Traffic and Transport Digest and Annual Digest of Statistics. Our calibration results show that urban taxi services in Hong Kong exhibit an increasing return to scale. The established simultaneous equation model can be used to obtain regulatory information useful for decision-making, such as the impact of the restriction over the number of taxi licenses and the fixing of taxi fare structure.

Equilibrium Model of Urban Taxi Service Network Based on the Integrated Service Modes

This paper proposes an equilibrium model of urban taxi services on network to present the impact of the integrated service modes and the influence of the elastic customer demand distribution on taxi network equilibrium. Based on the cruising service mode, the model can describe how occupied taxis and vacant taxis cruise on network to provide services and search for customers by considering both the expected time cost and ride revenue and the elastic distribution characteristic of customer demand. At the same time, the dispatch service equilibrium problem by researching trip mode choice behavior is also considered. The model can then establish the relationship between customer waiting time and taxi search/waiting time by introducing a taxi-customer meeting function. And moreover, in supply-demand equilibrium, a number of performance measures of the taxis market can be obtained, such as the number of cruising taxis, the number of dispatch taxis and the average customer waiting time.

Empirical evidence for taxi customer-search model

A mutinomial logit model of urban taxi services has been developed for the study of the operational characteristics of the taxi industry, in which it is hypothesised that the customer-searching behaviour of vacant taxis follows a multinomial logit choice model. Although the model is commonly used, little empirical evidence exists to validate the choice mechanism and determine the set of important factors that affect the choice. In the present study, a stated preference survey of 400 taxi drivers was conducted to analyse the customer-searching behaviour of vacant taxis. The results explain how the considered parameters of waiting time, journey time, travel distance and toll affect the driver behaviour when searching for customers. In addition, market segmentation analysis was carried out to study the effects of driver demographics and operational characteristics on the searching behaviour. The parameters that were considered in this section of the study were the age of the driver, taxi ownership, driver experience and marital status.

Modeling urban taxi services with multiple user classes and vehicle modes

This paper extends the model of urban taxi services in congested networks to the case of multiple user classes, multiple taxi modes, and customer hierarchical modal choice. There are several classes of customers with different values of time and money, and several modes of taxi services with distinct combinations of service area restrictions and fare levels. The multi-class multi-mode formulation allows the modeling of both mileage-based and congestion-based taxi fare charging mechanisms in a unified framework, and can more realistically model most urban taxi services, which are charged on the basis of both time and distance. The introduction of multiple taxi modes can also be used to model the differentiation between luxury taxis and normal taxis by their respective service areas and customer waiting times. We propose a simultaneous mathematical formulation of two equilibrium sub-problems for the model. One sub-problem is a combined network equilibrium model (CNEM) that describes the hierarchical logit mode choice model of occupied taxis and normal traffic, together with the vacant taxi distributions in the network. The other sub-problem is a set of linear and nonlinear equations (SLNE), which ensures the satisfaction of the relation between taxi and customer waiting times, the relation between customer demand and taxi supply for each taxi mode, and taxi service time constraints. The CNEM can be formulated as a variational inequality program that is solvable by means of a block Gauss–Seidel decomposition approach coupled with the method of successive averages. The SLNE can be solved by a Newtonian algorithm with a line search. The CNEM is formulated as a special case of the general travel demand model so that it is possible to incorporate the taxi model into an existing package as an add-on module, in which the algorithm for the CNEM is built in practice. Most of the parameters are observable, given that such a calibrated transport planning model exists. A numerical example is used to demonstrate the effectiveness of the proposed methodology.

Modeling the bilateral micro-searching behavior for urban taxi services using the absorbing markov chain approach

This paper develops a mathematical model that is based on the absorbing Markov chain approach to describe taxi movements, taking into account the stochastic searching processes of taxis in a network. The local searching behavior of taxis is specified by a logit form, and the O-D demand of passengers is estimated as a logit model with a choice of taxi meeting point. The relationship between customer and taxi waiting times is modeled by a double-ended queuing system. The problem is solved with a set of non-linear equations, and some interesting results are presented. The research provides a novel and potentially useful formulation for describing the urban taxi services in a network.

Modeling urban taxi services in road networks: Progress, problem and prospect

AbstractTraditionally, many economists have examined the models and economics of urban taxi services under various types of regulation such as entry restriction and price control in an aggregate way. Only recently have we modeled urban taxi services in a network context. A realistic method has been proposed to describe vacant and occupied taxi movements in a road network and taxi drivers' search behavior for customers. A few extensions have been made to deal with demand elasticity and congestion effects together with development of efficient solution algorithms. Calibration and validation of the network taxi service models have been conducted towards their practical applications. This paper presents an overview of the research that has been carried out by the authors to develop network equilibrium models and solution algorithms for urban taxi services, and offers perspectives for future researches.

Modeling urban taxi services in congested road networks with elastic demand

This paper extends the simple network model of urban taxi services proposed by Yang and Wong (Yang, H., Wong, S.C., 1998. Transportation Research B 32, 235–246). The extensions include incorporation of congestion effects, customer demand elasticity, reformulation of the model and development of a new solution algorithm. Instead of the previous characterization of pure taxi movements in a network by a system of nonlinear equations, a two-level model formulation is proposed for taxi movements in congested road networks. The bi-level problem is a combined network equilibrium model that describes simultaneous movements of vacant and occupied taxis as well as normal traffic in a user-optimal manner for given total customer generation from each origin and total customer attraction to each destination. The upper-level problem is a set of linear and nonlinear equations ensuring that the relation between taxi and customer-waiting times and the relation between customer demand and taxi supply are satisfied. The lower-level problem can be solved by the conventional multi-class combined trip distribution and assignment algorithm, whereas the upper-level problem is solved by a Newtonian algorithm with line search. A numerical example is presented to illustrate the proposed model and algorithm and demonstrate the characteristics of the taxi services in congested road networks.

Modeling Level of Urban Taxi Services Using Neural Network

This paper is concerned with the modeling of the complex demand-supply relationship in urban taxi services. A neural network model is developed, based on a taxi service situation observed in the urban area of Hong Kong. The input consists of several exogenous variables including number of licensed taxis, incremental charge of taxi fare, average occupied taxi journey time, average disposable income, and population and customer price index; the output consists of a set of endogenous variables including daily taxi passenger demand, passenger waiting time, vacant taxi headway, average percentage of occupied taxis, taxi utilization, and average taxi waiting time. Comparisons of the estimation accuracy are made between the neural network model and the simultaneous equations model. The results show that the neutral network-based macro taxi model can obtain much more accurate information of the taxi services than the simultaneous equations model does. Although the data set used for training the neural network is small, the results obtained thus far are very encouraging. The neural network model can be used as a policy tool by regulator to assist with the decisions concerning the restriction over the number of taxi licenses and the fixing of the taxi fare structure as well as a range of service quality control.

A network model of urban taxi services

A network model is developed to describe how vacant and occupied taxis will cruise in a road network to search for customers and provide transportation services. The model can determine a number of system performance measures at equilibrium, such as vacant taxi movements and taxi utilization for a given road network and the customer origin–destination demand pattern. The effects of the taxi fleet size and the uncertainty on the system performances are explicitly taken into account. The model offers some interesting insights into the nature of the equilibrium of taxi services, and offers some policy-relevant results for decision making. These include the findings that the average taxi utilization decreases sharply with the number of taxis operating, and that the higher the taxi utilization, the larger the average customer waiting time.