Characterizing the performance of queuing networks in terminal control systems

The terminal infrastructure is critical for the effective and efficient operation of air traffic flow. The increase in air traffic flow creates pressure on air transport infrastructures and networks. Therefore, decision-makers need to develop and utilize efficient evaluation and analysis tools based on the limited availability of resources. Inspired by the underlying structure of queues for air traffic flow, a Petri-net-based model is developed in this study to characterize the system performance. In this study, air transportation networks are analyzed using a series of performance indicators that are based on a discrete-event system model.     

Urban taxis and air pollution: a case study in Harbin, China

Taxis share a high proportion of urban traffic volume and contribute a large proportion to urban air pollution. This paper addressees this context by exploring urban taxi air pollution emissions and possible reduction countermeasures. Based on a survey of Harbin taxis, we have developed different urban taxi pollution emissions models and considered taxi passenger occupancy and taxi average vacant ratio. To reduce taxi air pollution emission, this paper sets a reduction goal and puts forward three kinds of transport management policies. These are taxi market regulation, introduction of electric and Liquefied Petroleum Gas powered vehicles, and the introduction of dial-a-ride services. The paper provides recommendations for managing urban taxi development using these strategies.     

Revealing intra-urban travel patterns and service ranges from taxi trajectories

As an important transport tool, taxi plays a significant role to meet travel demand in urban city. Understanding the travel patterns of taxis is important for addressing many urban sustainability challenges. Previous research has primarily focused on examining the statistical properties of taxi trips to characterize travel patterns, while it may be more appropriate to explore taxi service strategies on seasonal, weekly or daily time scale. Therefore, intra-urban taxi mobility is investigated by examining taxi trajectory data that were collected in Harbin, China, while 12-week corresponding to 12-month is chosen as the sampling period in our study. The multivariate spatial point pattern analysis is firstly adopted to characterize and model the spatial dependence, and infer significant positive spatial relationships between the picked up points (PUPs) and the dropped off points (DOPs). Secondly, the points of interest (POIs) are identified from DOPs using the emerging hot spot detection technique, then the taxi services and movement patterns surrounding POIs are further examined in details. Moreover, our study builds on and extends the existing work to examine the statistical regularities of trip distances, and we also validate and quantify the impacts posed by airport trips on the distance distributions. Finally, the movement-based kernel density estimation (MKDE) method is proposed to estimate taxis' service ranges within three isopleth levels (50, 75 and 95%) between summer/weekday and winter/weekend from taxi driver's perspective, and season as well as temperature factors are identified as the significant effect within certain service range levels. These results are expected to enhance current urban mobility research and suggest some interesting avenues for future research.     

Analysis of ground access modes choice King Khaled International Airport, Riyadh, Saudi Arabia

Airports are vital to the transportation system because air travel is the fastest means of transporting people and goods around the world. Airports also connect aviation systems with other modes of transportation.As a result, access modes to airports are critical to the aviation system, and studying air passenger decisions regarding mode choice is an essential part of airport management and system planning.Though there has been systematic analysis of car use to access airports, there has been less systematic attention to the use of the public transport system, especially the taxi service. The aim of this study is to identify King Khaled International Airport (KKIA) access mode characteristics and users, which has not been investigated previously concentrating on the mix between car and taxi using data collected specifically for this research.More than half (55.5%) of the travelers surveyed arrived at KKIA by private car; taxi and limousine passengers accounted for 42.2% of the sample. The Saudi Public Transit Company (SAPTCO), transported only 2.3% of the air passengers surveyed. These results are similar to findings for an airport in the United States and very different from findings for an airports in the East (e.g., Hong Kong).A binary logit model was developed to evaluate the access mode choice. It was found that income, luggage, travel access time, and nationality significantly affect mode choice.Results provide insight for improved planning of access to KKIA.     

Study of emerging air taxi network operation using discrete-event systems simulation approach

This research focuses on understanding the air taxi operations to determine the number of air taxis required to fulfill the demand for urban air mobility in New York City (NYC). We leverage the Define, Measure, Analyze, Design, and Verify (DMADV) framework and integrate it with the systems simulation approach. Upon investigation, we find that all the parameters linearly impact the vehicle utilization, while other measures are robust, specifically with respect to the seating capacity. It is also recommended to operate initially with 70 air taxis in NYC to achieve a trade-off between customer wait time and vehicle utilization. The proposed approach can act as a recommender system for air taxi companies.     

Customer perspective on overbooking: The failure of customers to enjoy their reserved services,accidental or intended?

Overbooking is widely applied in the service industry to hedge against undesirable situations, such as cancellations and no-shows. However, during the implementation of overbooking, service providers may turn down some customers when the number of arrivals exceeds their capacity on the target date. Therefore, this paper examines overbooking from the customers' perspective to offer them a clear perception on the possibility for their reservations to be denied by the service provider. By establishing a Stackelberg model between a service provider and an online travel agency, we explore how optimal overbooking strategy is developed by the service provider. Afterward, by analyzing the obtained optimal overbooking pad, we calculate the probabilities of denied service under different levels of monetary compensation that is paid to denied customers. A higher monetary compensation guarantees a higher chance of successful service. This paper also provides customers with some reference when booking services.     

A diagrammatic analysis of the market for cruising taxis

A diagrammatic approach is used to study the characteristics of the cruising taxi market. For cost modeling, both taxi operator and passenger are taken as service producers. The former provides his vehicle operation and the latter, his waiting and travel time. Market demand is defined as a function of generalized price. It is shown that under short and long run conditions a unique equilibrium exists for a deregulated industry and it corresponds to a monopolistic competition. The relations among the free market equilibrium, social optimum and second best solution are analyzed. Regulations are studied in order to find their social convenience.     

A model for taxi pooling with stochastic vehicle travel times

Taxi pooling means the sharing of a taxi by more than one passenger with at least a semi-common route. Currently, a trial-and-error process is adopted, taking into account expected travel times, for taxi pooling, a method which is neither effective nor efficient. This is because stochastic disturbances arising from variations in the taxi travel times that occur in actual traveling are neglected. In the worst case scenario, where vehicle travel times fluctuate wildly during operations, the planned schedule can be disturbed enough to lose its optimality. Therefore, in this study, a network flow technique is used to construct a stochastic taxi pooling model incorporating stochastic vehicle travel times. A solution algorithm is also proposed to efficiently solve the problem. The performance of the proposed models and the use of the solution method in practice are evaluated by executing numerical tests using real data with suitable assumptions. The test results show that the stochastic model and the solution method could be useful references for practice.     

From traditional to professional Air Navigation Service Provider: A typology of European ANSP business models

This paper proposes a business model typology based on factor analysis of mixed data sourced from the 2016 Air Traffic Management Cost Effectiveness (ACE) benchmarking report, European air navigation service provider (ANSP) websites and annual reports. It provides ANSP management insight into the key strategic business model decisions to be made, their resulting models as well as how these business model decisions contribute to ATM/CNS profits. The findings suggest that ANSPs can benefit from increasing both their level of corporatisation as level of outsourcing. The paper can be used by ANSP managers to position themselves within the European air navigation services (ANS) landscape and as a discussion starter for future business model developments; or by ANS customers to better understand the strategic objectives of the ANSPs.     

A note on shared transportation for tourists with special reference to the Israeli sherut

In this note, we provide answers to two hitherto unstudied questions in the literature concerning the provision of shared transportation to tourists. First, we ascertain the long run fraction of time that there is no sherut taxi at a designated taxi stand. Second, we determine the long run fraction of tourists who are lost to the sherut taxi providing firm because no taxis are available when arriving tourists want a taxi. Finally, we show that these two long run fractions are equal because the so called PASTA property holds in our model. Copyright © 2009 John Wiley & Sons, Ltd.     

Route-charging policies for a central European cross-border upper airspace

The introduction of the Central European Air Traffic Services Upper Area Control Centre controlling the upper airspace of several European countries allows different route-charging policies. The impact of three charging scenarios on aircraft operators is examined. It is found that, without a compensatory mechanism, the policy of having different unit rates for each air navigation service provider would adversely affect regional and region-based carriers because the unit rate of the new provider would be significantly lower than the unit rates of the national providers controlling the lower airspaces.     

The redesign of a warranty distribution network with recovery processes

A warranty distribution network provides aftersales warranty services to customers and resembles a closed-loop supply chain network with specific challenges for reverse flows management like recovery, repair, and reflow of refurbished products. We present here a nonlinear and nonconvex mixed integer programming model for the design of the warranty distribution network of a semiconductor company which is operated by an outsourced third party logistics service provider. The application of the model to the real-life case provides an improved distribution network flow and rearranged warehouse and recovery locations, and resulted in weekly cost savings of 3.4% for the considered item.     

Analysis of the effect of charging infrastructure design on electric taxi driving profiles: A case study approach on the example of Singapore

Replacing conventional vehicle taxis with electric vehicles would be an efficient measure to reduce greenhouse gas emissions. Due to the limited range and long charging times of current battery electric vehicles, it is of utmost importance to provide sufficient charging facilities. This article analyses the impact of the placement and charging power of charging stations on potential mileage and revenue of electric taxis on the example of Singapore. Therefore, we developed an agent-based electric taxi simulation model to investigate electric taxis’ driving profiles with respect to different vehicle types and charging infrastructure designs. This model is also capable of simulating conventional taxi driving profiles. The validation of these simulation results with real taxi data showed that the model is reproducing taxi driving profiles with high accuracy in great detail. We found out that electric taxis could reach the same mileage and revenue as conventional taxis if charging with a power of 160?kW is possible. Furthermore, we discovered that waiting times for available charging stations have a stronger effect on revenue than the length of detours to reach charging stations. Based on these findings, we concluded that it is more important to reduce waiting times by placing sufficient numbers of charging stations at each location before expanding the charging network by installing small numbers of charging stations at many locations.     

Conditions for electric vehicle taxi: A case study in the Greater Stockholm region

This study investigates the usability of electric vehicles (EVs) in a taxi company in Greater Stockholm, Sweden. By investigating cost and revenue data of both electric and conventional taxi vehicles, as well as by interviewing taxi drivers and carriers, an assessment has been made of the financial and operational implications of using EVs in a company’s taxi fleet. Both the drivers’ and the carriers’ perspectives have been examined. The main findings are that the investigated e-taxis have a similar or lower Total Cost of Ownership and slightly higher profitability than the investigated conventional taxis. For taxi drivers, using e-taxis implies more advanced planning and revenue service time being sacrificed for charging. However, certain customers’ preferences for EVs, as well as benefits such as corporate clients favoring e-taxis and a zero emission priority queuing system at Stockholm’s main international airport (partly) compensate for time devoted to charging. In order to facilitate increased use of e-taxis, more fast charging facilities should become available at strategic locations. Besides that, there are signs that carriers’ lack of information about the opportunities and consequences of shifting towards e-taxis hamper a wider deployment of e-taxis.     

Dually sustainable urban mobility option: Shared-taxi operations with electric vehicles

Electric vehicles (EVs) are energy efficient and often presented as a zero-emission transport mode to achieve long-term decarbonization visions in the transport sector. The implementation of a sustainable transportation environment through EV utilization, however, requires the addressing of certain cost and environmental concerns such as limited driving range and battery-charging issues before its full potential can be realized. Nevertheless, a specific type of use of EVs, namely in taxi services, may elicit positive public opinion, as it promises a commitment toward sustainability in urban life. In light of this, this study proposes an integrated approach that combines EV operation with a conceptual design for shared-ride taxi services. As some productivity loss may be naturally expected due to the time spent in charging, it is important to look at whether such performance loss from the passenger and system standpoints can be offset with ingenuity in operational design. In this study, an EV taxi charge-replenishing scheme that can be coupled with a real-time taxi-dispatch algorithm is designed. The proposed EV charging schemes for taxi services are studied via simulations and the effects of the limited driving range and battery-charging details are examined from a system performance viewpoint. The simulation study also reveals illustrative results on the impact of the EV taxi fleet's operation on the charging system. Next, a real-time shared-taxi operation scheme that allows ride sharing with other passengers is proposed to maximize the operational efficiency. The simulation results suggest that the shared-taxi concept can be a viable option to improve on the limitations caused by EV operation. In addition, the importance of projected charging demands and queue delays at different charging locations are also addressed. Some limitations and a future research agenda are also discussed.     

An exploratory empirical analysis of willingness to hire and pay for flying taxis and shared flying car services

A new transportation mode that can simultaneously operate on land and in the air, namely the flying cars, is anticipated to penetrate the automobile fleet between 2020 and 2025. Due to their flexible mobility patterns and automated operational characteristics, flying taxi and shared flying car services are expected to expand the existing shared mobility services (such as Uber, Lyft, and similar services) of the urban transportation network. Despite their forthcoming introduction in the shared mobility market, public perceptions and expectations about these services have not been investigated in travel demand literature. This study aims to provide an exploratory analysis of public willingness to hire and pay for flying taxis and shared flying car services, and to identify the determinants of the willingness to hire and pay for such services. Using data collected from an online survey, individuals' willingness to hire and to pay for flying taxi and shared flying car services are statistically modeled within a correlated grouped random parameters bivariate probit framework. The analysis shows that various socio-demographic characteristics and individuals’ opinions towards the perceived benefits and challenges of flying cars affect public willingness to hire and pay for flying taxi and shared flying car services. Even though the awareness about the operation of flying taxis and shared flying car services is possibly limited in the public sphere, the findings of this study can provide insights into the challenges that policymakers, manufacturing companies, and shared mobility providers will face with the introduction of such flying car services in the transportation networks.     

Stated-preference analysis to estimate the domestic transport demand following the future entry of LCCs and the inauguration of the Linear Chuo Shinkansen in Japan

Using a stated-preference survey, we examine changes in air transport demand by the entry of low cost carriers into domestic service, and with the beginning of operation of the Linear Chuo Shinkansen. In order to construct a choice model, we estimate the Nested-Logit model parameters by the two kinds of travel purposes in order to consider the differences in the price-sensitivity between business and non-business travelers. Simulation results for the each targeted OD vary in the shares of each transportation mode, depending upon the travel times, the aviation network, travel purpose. Non-business travelers who are more price-sensitive are less likely to choose the Linear Chuo Shinkansen with higher fares. On the route between the metropolitan area and Kinki area, total aviation demand will increase by the entry of LCCs to/from Tokyo-Haneda airport even when the Linear Chuo Shinkansen begins operating, showing that the development of the Linear Chuo Shinkansen service will not prevent strong growth in aviation demand for the trunk domestic routes.     

Looking for the obvious: Motorcycle taxi services in Sub-Saharan African cities

Motorcycle taxis (MCT) have been present in many cities of Sub-Saharan Africa for several decades. This paper aims to answer two questions: How can we objectify the massive and lasting development of a “motorcycle taxi model” in the cities of SSA? How does this model function in practice? First, the spread of motorcycle taxis in Sub-Saharan Africa is examined by using an internet-based bibliometric analysis of academic output and local press articles. Second, the functioning of the industry and the informalization rationales at work in the deployment of the motorcycle taxi model are analyzed on the basis of a field study in Lomé, the capital of Togo.The bibliometric analysis of the academic output shows the presence of MCT in 14 countries over a 30 year period, and that of the local press almost doubles the number of countries. It also provides some temporal reference points and suggests some reasons for MCT deployment. Three main features of the functioning of the MCT industry in Lomé are identified: the equivocal attitude of the State, the heterogeneous characteristics of the players, and the strong and multifaceted linkages of MCT with formal activities. The results from this research provide evidence that the development of the motorcycle taxi model in SSA is closely associated with globalization and informalization processes.     

Examining the spatial-temporal relationship between urban built environment and taxi ridership: Results of a semi-parametric GWPR model

With the advance of intelligent transportation systems (ITSs) and data acquisition systems (DASs), it becomes possible in recent to explore the determinants of urban taxi ridership using multi-source heterogeneous data. This paper aims to use floating car data, points-of-interests (POIs) data and housing-price data to assess the influence of the built environment on taxi ridership. Within a scale of 0.5 km grid, critical indicators related to the economic aspect, intermodal connection, and land use factors were obtained using the multi-source data in Shanghai. To capture the spatial and temporal heterogeneity, Semi-parametric Geographically Weighted Poisson Regression (SGWPR) models are built over different time dimensions. It is found that SGWPR models result in higher goodness-of-fit than the generalized linear models. More importantly, the results show the impacts of built environment factors on taxi demand are highly heterogeneous, positive or negative in different city areas, reflected in the significant temporal variations of the effects. Overall, these findings suggest that the built environment factors have significant impacts on urban taxi demand, and the spatial context should not be ignored. Findings in this paper are expected to help better understand the relationship between urban taxi demand and built environment factors, improving the service level of the urban taxi system, and offering valuable insights into future urban and transportation planning.     

Pricing strategies for a taxi-hailing platform

Taxi hailing apps that facilitate taxi-customer matching quickly become popular in recent years. By combining the theories of two-sided market and taxi market, this paper models the taxi market in the presence of a single taxi hailing app through an aggregate and static approach. Based on the equilibrium model, the existence and stability of equilibria are examined, and a partial-derivative-based sensitivity analysis is conducted to quantitatively evaluate the impacts of the platform’s pricing strategies to the taxi market performance. The features of desirable price perturbations that improve social welfare and/or the platform’s profitability are also characterized.