Taxi Operations Research Articles

Dynamic modeling and control of taxi services in large-scale urban networks: A macroscopic approach

Taxis are increasingly becoming a prominent mobility mode in many major cities due to their accessibility and convenience. The growing number of taxi trips and the increasing contribution of taxis to traffic congestion are cause for concern when vacant taxis are not distributed optimally within the city and are unable to find unserved passengers effectively. A way of improving taxi operations is to deploy a taxi dispatch system that matches the vacant taxis and waiting passengers while considering the search friction dynamics. This paper presents a network-scale taxi dispatch model that takes into account the interrelated impact of normal traffic flows and taxi dynamics while optimizing for an effective dispatching system. The proposed model builds on the concept of the macroscopic fundamental diagram (MFD) to represent the dynamic evolution of traffic conditions. The model considers multiple taxi service firms operating in a heterogeneously congested city, where the city is assumed to be partitioned into multiple regions each represented with a well-defined MFD. A model predictive control approach is devised to control the taxi dispatch system. The results show that lack of the taxi dispatching system leads to severe accumulation of unserved taxi passengers and vacant taxis in different regions whereas the dispatch system improves the taxi service performance and reduces traffic congestion by regulating the network towards the undersaturated condition. The proposed framework demonstrates sound potential management schemes for emerging mobility solutions such as fleet of automated vehicles and demand-responsive transit services.

Taxi vacancy duration: a regression analysis

ABSTRACTTaxi vacancy duration is a major efficiency measure for taxi services. A clear understanding of the various factors and their effect on vacancy duration is necessary for the optimal operational management of taxis. Previous research has only dealt with vacancy duration by assuming probability distributions and has not investigated heterogeneity in the data caused by various factors. We develop a parametric duration model using not only new operational characteristics but also variables associated with taxi demand, such as weather, land use, demographics, socioeconomic variables, and accessibility of public transportation. The model is applied to a large-scale New York City (NYC) taxi trip dataset that covers operations for 2013. The results show that all the attributes have significant associations with vacancy duration that follows a log-normal distribution. Our study is expected to help improve the efficiency of taxi operations by decreasing the time spent in vacant states.

Reducing the air quality and CO2 climate impacts of taxi and takeoff operations at airports

Aircraft activity at airports is a source of CO2 emissions that affect the climate and other pollutants that affect air quality and human health. We estimate the air quality and climate benefits of two measures applied to aircraft operations at the Detroit Metropolitan Airport – pushback control and de-rated takeoffs. We also calculate the minimum air quality and environmental impacts beyond fuel burn and CO2 minimization by optimizing gate holding and takeoff thrust hourly over the year. Pushback control (i.e. holding aircraft at their gates up to 25 min to reduce congestion) minimizes fuel burn and reduces emissions and air quality impacts from taxi operations by 35–38% relative to no gate holds. The PM2.5 and O3 costs can be further reduced beyond fuel burn minimization by 2.7% and 8.5%, respectively, by optimizing the gate holds according to time-varying atmospheric conditions. De-rated takeoffs (i.e. takeoffs at 75% thrust) reduce PM2.5 costs from takeoff operations by 18% (up to 21.6% when optimized) relative to full-thrust takeoffs, but result in 3% increased fuel burn and CO2 climate impacts. The environmental costs of takeoff operations are minimized with an average thrust setting of 81%, while total fuel combustion-related costs (i.e. the sum of environmental, fuel and maintenance costs) are minimized with 75% thrust. Our findings suggest that the pushback control strategy is effective in mitigating the environmental impacts of taxi operations at airports, and that de-rated takeoffs are effective in reducing the environmental costs of takeoff operations at an optimal level of de-rate.

Multiple fault-based FDI and reconfiguration for aircraft engine sensors

PurposeCondition monitoring and health management of an aircraft engine is of importance due to engine’s critical position in aircraft. Missions require uninterrupted and safer conditions during the flight or taxi operations. Hence, the deviations, abnormal situations or failures have to be under control. This paper aims to propose a cascade connected approach for an aircraft engine fault tolerant control.Design/methodology/approachThe cascade connected structure includes a full-order unknown input observer for fault detection and eliminating the unknown disturbance effect on system, a generalized observer scheme for fault isolation and a Boolean logic mechanism for decision-making in reconfiguration process, respectively. This combination is simulated on a linear turbojet engine model in case of unknown input disturbance and under various sensor failure scenarios.FindingsThe simulation results show that the suggested fault detection isolation reconfiguration (FDIR) approach works effectively for multiple sensor failures with various amplitudes.Originality/valueDifferent from other studies, the proposed model is sensitive to unknown input disturbance and failures that have unknown amplitudes. One another notable feature of suggested FDIR approach is adaptability of structure against multiple sensor failures. Here, it is assumed that only a single fault is to be detected and isolated at a time. The simulation results show that the proposed structure can be suggested for linear models especially for physical redundancy-based real-time applications easily, quickly and effectively.

Mining factors affecting taxi drivers’ incomes using GPS trajectories

Taxis provide essential transport services in urban areas. In the taxi industry, the income level remains a cause of concern for taxi drivers as well as regulators. Mining underlying factors affecting the income level will not only benefit the newcomers and low-income drivers but also assist in developing effective optimization algorithms for taxi operations. This paper intends to disclose the factors affecting incomes along with their quantitative influence by mining over 167 million GPS records from nearly 8000 taxis in Shanghai. We first identify a marked difference in drivers’ incomes and categorize drivers into three income levels accordingly. We next investigate the overall search-delivery process, thereby defining several factors that may affect the income level. We then develop a generalized multi-level ordered logit (GMOL) model to find the significant factors that influence incomes. Finally, we compute the elasticity for those significant factors and present their contributions, as well as challenge some preconceived ideas regarding how to earn high incomes.

BICYCLES TRANSPORT SUSTAINABILITY OPPORTUNITIES FOR TOURISM DEVELOPMENT: CASE STUDY OF MZUZU CITY, MALAWI

PurposeThe objective of the study is to investigate and critically analyze the sustainability of bicycle taxi transport as informal business operation, the operators prevailing challenges and its contribution to sustainable urban transport and tourism development in Mzuzu City, Malawi.Design / Methodology/ApproachThe study was conducted with ten bicycle taxi operators, road users, and two city council and two government authorities in Mzuzu City, Malawi. The sampling technique for bicycle taxi operators was random to collect primary data whereas authorities from city council and government used a representative sampling technique to collect both primary and secondary data type (rules documents and regulations as well as by-laws). The research used both questionnaire and in-depth interviews. In this case, mixed method approach suited very well with a small sample in a small tourist city.FindingsThe empirical results reveal that bicycle taxi operators are called periodically by road traffic officials and provide them with an awareness on how to operate on the roads within the city. It also reveals that there is no law that restricts operators from riding a bicycle in the city. Furthermore, reveals that bicycle taxi operators do not cause accidents, but rather accidents are caused by several factors, among them: pedestrians, drunkards, not following rules and regulation by road users. Therefore, bicycle taxi users vowed to continue using bicycles because there are cheap and can take them anywhere motorized cars cannot reach. Despite a few challenges operators are facing, bicycles transport will be sustained, hence contributing to domestic tourism development.Practical / Social ImplicationsThe study reveals that bicycle transport should be properly formalized and integrated into urban transport in Mzuzu City which would lead to the creation of an environmentally friendly city; continued provision of affordable public and tourists transport; and improving revenue base for the city council, as they will be able to collect revenue from the operators.The results of this study cannot be generalized since the researcher focused on one city with a very small population with a small sample size.Novelty / Originality There are very few studies or none existing at all conducted in tourism to study bicycle transport sustainability opportunities for tourism development in Malawi, and this may be first of its kind.

Determining locations of charging stations for electric taxis using taxi operation data

ABSTRACTThe adequate provision of charging infrastructure is critical for the effective deployment of electric taxis. This study attempts to locate charging stations for electric taxis reflecting real-world taxi travel patterns identified from taxis equipped with digital tachographs. Data for one week are processed in order to estimate their charge demand. The estimated temporal distribution of charge demand indicates that it varies day-by-day and hour-by-hour. The maximum set covering model is applied for determining the locations of charging stations. The results show that the pre-specified service distance and service coverage rate (defined by the proportion of total demand served) can be critical factors for determining the number and location of charging stations. These factors should be carefully specified by considering the tradeoff between operational efficiency of charging facilities and user convenience.

The Usage Analysis and Policy Choice of CNG Taxis Based on a Multi-stage Dynamic Game Model

The promotion and application of low-carbon energy has become a basic energy policy in China. In the taxi industry, the adoption of natural gas is a typical reflection of the use of low-carbon energy, however, the application of CNG taxis in practice is difficult because of the ignorance of consumer behaviour choices and the lack of consideration of the reforming and maintenance costs of CNG taxis in practical use during the implementation of this policy. In this paper, the construction of a multi-stage dynamic game model is proposed: this is used to analyse the complex dynamic relationships among consumers, the taxis, and the policy-making behaviours of government. By the means of backward induction, a conclusion is drawn such that government should determine the subsidy coefficientper unit of product as well as the carbon taxand the optimal reduction rate of carbon emissions confirmed by operators determination. Based on these, concerning the behavioural choices among consumers, taxis, and government, this paper draws five conclusions, which answer the problems concerning whether, or not, the government should levy a carbon tax and subsidise such operations as well as how much that financial levy and subsidy should be. Besides, this paper also makes a value judgment of the future format/mode of taxi operations. The study shows that, with the increasing subsidy, the competitive advantages of the CNG taxis are strengthened while the revenues of oil-fired taxis decrease constantly, which forces oil-fired taxis out of the market. At the same time, the service prices of both kinds of taxis are proportional to the money paid by consumers and the positive impacts of service prices on CNG taxis are greater than that on oil-fired taxis.The carbon tax standard set by government can play a proper role only if it gives consideration to the interests of both consumers and CNG taxis.

Comparative Analyses of Taxi Operations at the Airport

We propose statistical methodologies to investigate taxi operations at the airport. Based on Automatic Vehicle Location (AVL) data of nearly 9,000 taxis in five weekdays, we apply the proposed methodologies to evaluate taxi operations at Shanghai's Hongqiao international airport. The empirical studies statistically compare the operations of taxis serving the airport and urban areas and identify the periods in which the taxi profits are relatively stable. Possible explanations for the empirical results are provided. The findings would offer a better understanding of the mechanism that drives vacant-taxi drivers to serve the airport.

Humanistic management philosophy in governance in the taxi industry in South Africa

Ponte Academic JournalMay 2017, Volume 73, Issue 5 Humanistic management philosophy in governance in the taxi industry in South AfricaAuthor(s): Vimolan Mudaly ,Kudakwashe ZvitamboJ. Ponte - May 2017 - Volume 73 - Issue 5 doi: 10.21506/j.ponte.2017.5.36 Abstract:Small and medium enterprises sustainability and governance recently become a topical issue. Governance applicable to companies (corporate governance) had been questionable due to a plethora of scandals, ethics issues and corruption happening in companies. Therefore, applicability of corporate governance to small and medium enterprises like the minibus taxi industry has been questioned. These challenges caused the study to explore humanistic management philosophy in governance with specific reference to the Port Shepstone minibus taxi industry in KwaZulu -Natal, South Africa. Humanistic management philosophy was put forward as an alternative to economicism philosophy in governance. The study wanted to establish the extent to which humanistic management strategy, humanistic management leadership, humanistic management ethics and humanistic management culture affect governance of small and medium enterprises like the minibus taxi industry. These objectives were viewed using Ubuntu philosophy as a theoretical framework. The study adopted a concurrent triangulation mixed method approach advocated by post-positivists. A mixed method approach taps into the advantages of both qualitative and quantitative approaches to gather rich data which explained the phenomenon. The case study designed used enabled the study to do an in-depth analysis of the phenomenon on one industry (minibus taxis industry). The research methods used were questionnaires, observation and interviews to gather data. The data was gathered from minibus taxi operators. The integration of results from research methods generated a generalisation. The results revealed that humanistic management philosophy in governance of the minibus taxi industry was a challenge. The taxi operators, as owners of the business, were not implementing humanistic management leadership principles, humanistic management strategies, humanistic management ethics and humanistic management culture in governance. This affected their sustainability due to conflict with stakeholders. This contradicted the expectation of stakeholders who believe in African philosophy (Ubuntu). The governance of the small and medium enterprises like the minibus taxi industry was based on economicism philosophy instead of humanistic management philosophy. Therefore, the study recommended a humanistic management philosophy in governance model to guide small and medium enterprises in their business governance. Download full text:Check if you have access through your login credentials or your institution Username Password

The Future of Conventional Aircraft Ground Propulsion Systems in Relation to Fuel Consumption and CO2 Emission

Aircraft spends a minimum of 20 minutes using its main engine to taxi from the airport terminal gate to the runway, where the aircraft takes-off and similarly to the terminal gate after landing. During taxi operation, aircraft burns a lot of fuel, generates large quantity of emissions and the engine in the process of taxiing is exposed to damage due to Foreign Object Damage (FOD). This results in huge operational and maintenance cost as well as carbon emission tax which are all at the expense of the airline. EGTS is a recent technology designed to prevent aircraft from using its main engine for taxi operation and this in turn reduces the rate of fuel consumption, slashes carbon emissions and minimises operational and maintenance cost. This paper examines the viability of using EGTS in single engines for taxi operation rather than the aircraft engine. Block fuel savings was calculated for two engine, single engine and hybrid aircraft and it was observed that two engine aircraft using EGTS saved 110kg block fuel, single engine saved 74kg and for hybrid engine the block fuel savings was 50kg. Block fuel savings was calculated for aircraft such as airbus A320, airbus A380, Cessna 172 and A600ST and it was observed that EGTS is more compatible with airbus A320 but was not recommended for A600ST and A380 due to extra weight implication and for Cessna 172, EGTS was not necessary because the aircraft weight is low and consumes less fuel already. It was observed that the higher the aircraft weight including the extra weight of EGTS, the higher the fuel consumption emission as well as the torque required to overcome drag force when the aircraft operates in air. CO2 emission was also calculated for aircraft with EGTS and aircraft without installation, the result for aircraft with EGTS showed 797.56kg reduction of CO2 emission when compared to aircraft without EGTS. Comparably, EGTS was proven to be viable in terms of fuel savings, CO2 emissions, operational and maintenance cost than its contemporary Ground Propulsion Systems (GPS) for single aircraft engines and therefore, was recommended for aircraft in airbus A320 category to help minimise global warming which results from CO2 emission during taxing operations.

Framework for automated taxi operation: The family model

Abstract: Replacement of conventional taxis by automated vehicles will challenge taxi operation in many ways. Decisions made by taxi drivers will be substituted by an integrated scheduling system that also manages the non-revenue generating activities such as vehicle pre-allocation, recharging and service trips. In order to tackle this challenge, this study introduces a theoretical framework for autonomous vehicles based on the model of a family. The family model decomposes the complexity of scheduling for automated vehicle fleets. It allows vehicles to negotiate among them in a decentralized fashion and at the same time it allows the fleet manager to set fleet priorities and to pre-allocate vehicles in locations of expected future demand. Furthermore, it proposes a transparent framework for communication with service providers. Moreover, this study discusses selected opportunities and challenges of automated vehicle fleets.

Urban Taxi Ridership Analysis in the Emerging Metropolis: Case Study in Shanghai

Abstract Taxicab is one of the critical components of the urban mobility in most metropolitan areas on the world, especially in the emerging countries. Last year in Shanghai, the total 50,000 taxicabs carry 2.8 million passengers and travel 17.1 million kilometers every day. The tremendous amount of the stochastic and independent trips across the city makes the taxi problem more complex than transit such as bus and metro. Multi-source data over space and time provide an efficient way to explore the taxi ridership and travel pattern. In this study, we first summarize the historical operation records of Shanghai taxicabs, and then compare the temporal and spatial variation patterns of the taxi trips in Shanghai and New York City using GPS data. A regression model is developed to investigate the relationship between ridership and variables including urban land use, resident population, employment and car ownership. The results of this study may first improve the transportation model, and also benefit the efficiency of taxi operation and policy making.

The Analysis of Taxi Operation Features in Chinese Large Cities Based on Floating Cars

The Analysis of Taxi Operation Features in Chinese Large Cities Based on Floating Cars

Dynamic modeling and control of taxi services in large-scale urban networks: A macroscopic approach

Abstract Taxis are increasingly becoming a prominent mobility mode in many major cities due to their accessibility and convenience. The growing number of taxi trips and the increasing contribution of taxis to traffic congestion are cause for concern when vacant taxis are not distributed optimally within the city and are unable to find unserved passengers effectively. A way of improving taxi operations is to deploy a taxi dispatch system that matches the vacant taxis and waiting passengers while considering the search friction dynamics. This paper presents a network-scale taxi dispatch model that takes into account the interrelated impact of normal traffic flows and taxi dynamics while optimizing for an effective dispatching system. The proposed model builds on the concept of the macroscopic fundamental diagram (MFD) to represent the dynamic evolution of traffic conditions. The model considers multiple taxi service firms operating in a heterogeneously congested city, where the city is assumed to be partitioned into multiple regions each represented with a well-defined MFD. A model predictive control approach is devised to control the taxi dispatch system. The results show that lack of the taxi dispatching system leads to severe accumulation of unserved taxi passengers and vacant taxis in different regions whereas the dispatch system improves the taxi service performance and reduces traffic congestion by regulating the network towards the undersaturated condition. The proposed framework demonstrates sound potential management schemes for emerging mobility solutions such as fleet of automated vehicles and demand-responsive transit services.

Fixed‐route taxi system: route network design and fleet size minimization problems

SummaryThis paper introduces the taxi route network design problem (TXRNDP) for a fixed‐route taxi service operating in Iran and, in similar form, in various other developing countries. The service operates fairly similar to regular transit services in that vehicles are only permitted to follow a certain predetermined route on the network. The service is provided with small size vehicles and main features are that vehicles only depart if full and that there are no intermediate boarding stops. In Iran the service attracts a high modal share but requires better coordination which is the main motivation for the present study. We develop a mathematical programming model to minimize the total travel time experienced by passengers while constraining the number of taxi lines, the trip transfer ratio and the length of taxi lines. A number of assumptions are introduced in order to allow finding an exact rather than heuristic solution. We further develop a linear programming solution to minimize the number of taxis required to serve the previously found fixed‐route taxi network. Results of a case study with the city of Zanjan, Iran, illustrate the resulting taxi flows and suggest the capability of the proposed model to reduce the total travel time, the total waiting time and the number of taxi lines compared to the current taxi operation. Copyright © 2016 John Wiley & Sons, Ltd.

‘Double Capture’ and De-Democratisation: Interest Group Politics and Uganda’s ‘Transport Mafia’

This article analyses problems of interest representation and democratic consolidation, using a case study of the Uganda Taxi Operators and Drivers Association (UTODA). It shows how apparently representative organisational forms can exploit the majority of their members, bolstering the power of political-economic elites who straddle the state-society divide, as well as how such organisations can undermine the foundations for democratic consolidation more broadly. Challenging conventional understandings of ‘state capture’, the paper argues that UTODA’s organisational power instead evolved through processes conceptualised as ‘double capture’: first, the government infiltrated the informal transport sector, but subsequently the transport organisation came to wield disproportionate influence over the state itself, with detrimental effects on both urban services and popular representation. The long-term domination by this authoritarian organisation meant that even after its downfall in 2011 there was little organisational capacity to build on in the sector, facilitating the reassertion of top-down governmental control.

Guest Editorial: Big Data for Driver, Vehicle, and System Control in ITS

The papers in this special section are devoted to the topic of Big Data for intelligent vehicle systems. issue. The collection of papers included can be categorized in several ways. In terms of applications, the special section covers transit network design, taxi and bus operation, traffic flow and travel time prediction, dilemma zone management, and geometric design of roads. In terms of data sources, it covers both conventional sources of data such as bus, taxi, and individual vehicle trajectories, and also novel sources of data such as those based on the connected vehicle technology, roadside communication equipment, or onboard devices. In terms of techniques or methodologies developed for processing big data, this collection includes papers covering the data imputation technique based on the k-nearest neighbor method, data management infrastructure, the machine learning approach, and the graph-theory-based method.

The Current Situation of Electric Taxi Operations in China: Dilemmas and Solutions

The Current Situation of Electric Taxi Operations in China: Dilemmas and Solutions

Are Traditional Taxi Firms Doomed? An Answer from the Capital Market

Entry will occur most rapidly in a market where entrants incur few or no sunk costs, do not operate at a cost disadvantage, and where consumers can easily switch from the incumbent to the entrant. The purpose of this paper is to evaluate the speed of entry in an in industry that is highly contestable, taxi rides. In recent years, firms like Uber have entered the transportation business offering a ride service that competes with the traditional yellow cab service. Uber drivers have a lower cost structure than the incumbents, sunk costs are minimal, and they are able to enter the market knowing that the incumbent’s price is sticky downwards due to municipal regulations. These industry attributes have led many an observer to comment that the rents or profits earned driving a yellow cab will quickly wither away, or stated differently, the yellow taxis have little long-term market power. Despite these favorable entry conditions, I use capital market data to show that taxi operators have been betting that market power will persist for well over fifteen years.