Demand-responsive Services Research Articles

Demand Responsive Services: Towards an Analytical Framework for Administrative Practice in Indigenous Settlements

Demand responsiveness is an established principle in the efficient operation of markets. The principle has been applied to government services in international development overseas, and mainstream government service delivery in Australia, but only recently to Indigenous settlements. Shifting the balance in services from supply to demand is seen to have the potential to improve access, outcomes, and sustainability of services. In Indigenous settlements, an important relationship between demand and supply of services does exist, but a deeper analysis is necessary beyond the economic model to account for the complex sociopolitical geographies involved. Further research is required to develop a framework to explain the interactions that occur in practice, to determine the conditions which permit productive relationships to develop between consumers and service providers. The article presents an analytical framework through which to proceed, structured around five proposed research questions.

Emissions of demand responsive services as an alternative to conventional transit systems

The environmental performance of public transport plays a key role in improving air quality in urban areas. An important way of improving existing transit services is to use innovative propulsive systems; however, this needs considerable financial resources that are not always available. Here we assess how the organizational form of the transit system may impact the environment relying on a new methodology that permits comparisons in terms of distance traveled between a traditional fixed-route and a demand responsive transit service. We apply an emission model to find the least polluting transit system under a broad range of scenarios with different road networks, service quality levels and demand densities. Results indicate that demand responsive transit services minimize emissions for high quality service level and low demand density scenarios. Furthermore, the possibility of employing smaller vans with lower emission factors guarantees additional substantial benefits in terms of atmospheric pollution for demand responsive transit services, thereby giving them a competitive advantage in virtually every case.

The importance of information flows temporal attributes for the efficient scheduling of dynamic demand responsive transport services

AbstractThe operation of a demand responsive transport service usually involves the management of dynamic requests. The underlying algorithms are mainly adaptations of procedures carefully designed to solve static versions of the problem, in which all the requests are known in advance. However there is no guarantee that the effectiveness of an algorithm stays unchanged when it is manipulated to work in a dynamic environment. On the other hand, the way the input is revealed to the algorithm has a decisive role on the schedule quality. We analyze three characteristics of the information flow (percentage of real‐time requests, interval between call‐in and requested pickup time and length of the computational cycle time), assessing their influence on the effectiveness of the scheduling process.

A model for the fleet sizing of demand responsive transportation services with time windows

We study the problem of determining the number of vehicles needed to provide a demand responsive transit service with a predetermined quality for the user in terms of waiting time at the stops and maximum allowed detour. We propose a probabilistic model that requires only the knowledge of the distribution of the demand over the service area and the quality of the service in terms of time windows associated of pickup and delivery nodes. This methodology can be much more effective and straightforward compared to a simulation approach whenever detailed data on demand patterns are not available. Computational results under a fairly broad range of test problems show that our model can provide an estimation of the required size of the fleet in several different scenarios.

Bespoke services for personal travel and goods movement

New technology with portable location and communication devices allied to real-time information and control/management systems will provide opportunities for a wide range of bespoke services, which will offer real and attractive alternatives to conventional use of the private car. Such services will support travellers in their use of various forms of transport. These will range from conventional public transport with fixed services through to taxi-type operations, depending on the situations of the traveller and the journey. Various forms of collective, flexible and demand responsive services can be envisaged to ‘fill the gap’ between conventional public transport and taxis. New automated systems will also have a role to play. Equally, new technology to identify, track, trace, communicate with and optimise vehicles could lead to substantial reductions in urban vehicle travel. In order to achieve these reductions and still meet specific customer requirements effective coordination of customer needs and service provision is required. This could include online guidance and routing; the mapping of re-fuelling needs of electric/hybrid delivery vehicles with priority access; and the use of unattended collection/delivery points. This paper focuses on issues emerging from a multidisciplinary literature review, which assesses past, current and potential future bespoke transport services. The review draws on domestic and international experience to determine common characteristics and understanding learned from the operation of such services to identify issues and characteristics that should be considered in potential future applications.

Rural Transit Systems Benefits in Tennessee: Methodology and an Empirical Study

This paper describes the application of a detailed benefits assessment framework and sensitivity analysis of the operation of rural public transit services in the state of Tennessee. The paper describes the major components of this benefits framework and its application to the demand-responsive services operated within the state during the 1998/99 fiscal year. An empirical analysis yields a benefit/cost ratio greater than 1.0, with benefits dominated by accessibility gains to current transit patrons through the provision of mobility-enhancing vanpool services. Without these services, the costs of providing an equivalent level of access to health care, job training, and other important household activities would be much higher. Improved and expanded transit rider-based data collection efforts are recommended.

Meta-Heuristics for a Class of Demand-Responsive Transit Systems

The demand-adaptive systems studied in this paper attempt to offer demand-responsive services within the framework of traditional scheduled bus transportation: Users call to request service between two given points and, in so doing, induce detours in the vehicle routes; at the same time, though, a given set of compulsory stops is always served according to a predefined schedule, regardless of the current set of active requests. The model developed to select requests and determine the routing of the vehicle yields a difficult formulation but with a special structure that may be used to develop efficient algorithms. In this paper, we develop, test, and compare several solution strategies for the single line-single vehicle problem that belong to two general meta-heuristic classes, memory-enhanced greedy randomized multistart constructive procedures, and tabu search methods. Hybrid meta-heuristics combining the two methods are also analyzed.

OPTIMAL FARE ARRANGEMENT AND OPERATIONS FOR DEMAND RESPONSIVE BUS SYSTEM IN SUBURBS

Mitsunori YOSHIMURAAssistant ProfessorSchool of EngineeringNippon Bunri University1727, Ichigi, Oita,870-0397 JapanFax: +81-97-593-2071E-mail: yoshimuramt@nbu.ac.jpMakoto OKUMURAAssociate ProfessorGraduate School of EngineeringHiroshima University1-4-1, Kagamiyama, Higashi-Hiroshima,739-8527 JapanFax: +81-82-424-7827E-mail: mokmr@hiroshima-u.ac.jpAkimitsu ISOZAKIGraduate StudentGraduate School of EngineeringHiroshima University1-4-1, Kagamiyama, Higashi-Hiroshima,739-8527 JapanFax: +81-82-424-7849E-mail: isoaki@hiroshima-u.ac.jpAbstract: Public transportation service is essentially based on the scale economy, whichcomes from that cost of one vehicle operation can be divided by many passengers sharing thatservice. Therefore, it becomes very dicult to provide service in the area with low densityof demand. Recently, in order to provide transportation service in such low density areas,demand responsive bus(DRB) gathers attention and expectations. This paper discusses themarket externalities in DRB system in suburb and show what kind of fare arrangement willbe needed to realize the eciency of the market. At first, we analyze the optimal divisionof resources between two kinds of buses; demand responsive service and direct trunk lineservice. Without any fare intervention, people try to overuse of DRB because they neglect theexternal e ects by their calls. Then we try to estimate the amount of the externalities and giveinformation for the additional price for DRB.Key Words: Demand responsive bus, Bus operation, Externality1. INTRODUCTIONTraditionally, in order to connect a downtown and suburban housing complexes which locateaway from the trunk road, a lot of direct bus lines are often provided. However, when thepopulation decreases in the future, enough large volume of demand to maintain such directbus service for each housing complex cannot be secured; any revisions of bus lines becomeinevitable. Then it is plausible that bus lines would be revised as some combination of thefollowing services; direct trunk line bus which runs only along the trunk road, detour typebus service which goes around each housing complex while running at the trunk road, and thedemand responsive bus (DRB) which goes around the housing complex according to the callsof the users (Suzuki, 2001).The flexibility of the operation that DRB can skip running in the unnecessary part has beenconsidered as an advantage characteristic of DRB system (Akiyama, T. et al., 2000). However,if someone calls a DRB, the external negative e ects will occur, such as the increase of therequired on vehicle time for the users who have already got on the bus at the outer bus stops,and the increase of waiting time of the users at bus stops in downstream where delay of arrivaltime occurs. In order to operate DRB eciently, it is important to understand the characteristicof the operation form with paying attention to such negative external e ects of bus calls on theother users.

Activity and Travel Changes of Users of Job Access Transportation Service: Analysis of a User Survey

The Job Access and Reverse Commute (JARC) program of the FTA provides funding to improve the access to and from jobs for welfare recipients and low-income individuals. The objective of the study was to develop a comprehensive profile of JARC service riders on several economic, social, perceptual, and travel-related indicators on the basis of a data set that was collected by the authors from riders of fixed-route and demand-responsive services in 23 locations across the country that were funded by this program. The economic indicators considered include incomes of riders, full-and part-time work status, employment tenure, reported changes in employment status (transitioning from unemployment to employment), and changes in wages incurred after using the service. Social indicators include vehicle ownership, driver's license, and educational attainment. Where possible, JARC service riders were compared with a national sample of automobile and transit users; the data for these measures were obtained from the d...

Activity and Travel Changes of Users of Job Access Transportation Service

The Job Access and Reverse Commute (JARC) program of the FTA provides funding to improve the access to and from jobs for welfare recipients and low-income individuals. The objective of the study was to develop a comprehensive profile of JARC service riders on several economic, social, perceptual, and travel-related indicators on the basis of a data set that was collected by the authors from riders of fixed-route and demand-responsive services in 23 locations across the country that were funded by this program. The economic indicators considered include incomes of riders, full-and part-time work status, employment tenure, reported changes in employment status (transitioning from unemployment to employment), and changes in wages incurred after using the service. Social indicators include vehicle ownership, driver's license, and educational attainment. Where possible, JARC service riders were compared with a national sample of automobile and transit users; the data for these measures were obtained from the decennial census. Two measures of perceived service dependency that indicate the importance of the service to the riders are discussed. In addition, a profile of travel-related changes incurred by riders as a result of service use is developed, including changes in mode of travel and travel times. Many of these indicators are differentiated on the basis of type of area and type of service. This analysis brings a user perspective into the discussion about low-income employment transportation services and highlights the diversity of impacts that job access transportation is having on the work and nonwork activities of low-income riders.

Innovative systems for the transportation disadvantaged: Toward more efficient and operationally usable planning tools

When considering innovative forms of public transport for specific groups, such as demand responsive services, the challenge is to find a good balance between operational efficiency and 'user friendliness' of the scheduling algorithm even when specialized skills are not available. Regret insertion-based processes have shown their effectiveness in addressing this specific concern. We introduce a new class of hybrid regret measures to understand better why the behaviour of this kind of heuristic is superior to that of other insertion rules. Our analyses show the importance of keeping a good balance between short- and long-term strategies during the solution process. We also use this methodology to investigate the relationship between the number of vehicles needed and total distance covered - the key point of any cost analysis striving for greater efficiency. Against expectations, in most cases decreasing fleet size leads to savings in vehicle mileage, since the heuristic solution is still far from optimality.

Network design for a grid hybrid transit service

In this paper, we develop an analytical model that aids decision-makers in designing a hybrid grid network that integrates a flexible demand responsive service with a fixed route service. The objective of the model is to determine the optimal number of zones in an area where each zone is served by a number of on-demand vehicles. The function of the on-demand vehicles is to transfer passengers to a fixed route line if the destination is to a different zone or to its final destination if it is within the same zone.

Emerging Techniques for Urban Transportation Planning

Despite several decades of intense effort, urban transportation planning is in its infancy of development and refinement, as evidenced by the fast pace of new techniques and methodologies being proposed and developed. In this series of two special issues on urban transportation planning, the first issue @Journal of Urban Planning and Development, 128~4!, 2002# focused on reviews of recent methodological advances. This second issue covers emerging techniques that extend the boundries beyond the traditional four-step planning methodology. Some of these techniques are drawn from other fields of studies. Others introduce new dimensions to reconsider the problem. All in all, these approaches open up new possibilities and dimensions as well as make planning procedures more robust, thereby enabling the planning results to be applicable to a wider range of scenarios and for the longerterm future. Six papers are contained in this special issue. Drawing from business and organizational scenario planning techniques, the paper by Zegras, Sussman, and Conklin, ‘‘Scenario Planning for Strategic Regional Transportation Planning,’’ proposes a scenarioplanning framework for regional transportation planning. The study reviews the context of scenario planning for regional transportation planning, illustrates the approach through application to the Houston, Texas, metropolitan area, and concludes with findings, lessons learned, and future potentials and refinements of the approach. To improve the analysis of multicommodity demand and traffic patterns of a city with multiple regional activity centers, the paper by Wong, Zhou, Lo, and Yang, ‘‘Improved Solution Algorithm for the Multicommodity Continuous Distribution and Assignment Model’’ develops a new combined distribution and assignment model. A unique feature of this approach is that the dispersion of demand is modeled as a continuous function over space, in contrast to the traditional approach where demands are lumped at origin nodes or centroids. The study then proposes an efficient algorithm to solve the formulation. In the third paper, ‘‘Balance of Car Ownership under User Demand and Road Network Supply Conditions—Case Study in Hong Kong,’’ Tam and Lam propose a new concept for estimating car ownership. It considers the interactions between user demands and road network supply conditions, thereby factoring in the congestion effect to the estimation of car ownership on top of the traditional socioeconomic characteristics of the population. The paper then illustrates the approach through a case study in Hong Kong. Understanding users’ routing strategies is important, as it will lead to the design of more robust transportation networks. The paper by Bell, ‘‘Games, Heuristics, and Risk Averseness in Vehicle Routing Problems,’’ develops an approach for vehicle routing in networks with uncertain travel times. The study focuses on the case of freight carriers, wherein the dispatcher seeks a riskaverse routing and scheduling strategy. The writer formulates the problem with a game theoretic approach and solves it with a method of successive averages scheme. For low-density urban developments that render conventional transit services less competitive or cost-effective, perhaps only demand-responsive transit services are viable, if any at all. The paper by Khattak and Yim, ‘‘Traveler Response to Innovative Personalized Demand-Responsive Transit in the San Francisco Bay Area,’’ investigates the market for Personalized Demand Responsive Transit ~PDRT!. The study attempts to understand travelers’ willingness to use and pay for PDRT based on focus group meetings and a computer-assisted telephone survey. Such results are indicative for the planning of demand-responsive transit services. Finally, the paper by Ceder, ‘‘New Urban Public Transportation Systems: Initiatives, Effectiveness, and Challenges,’’ examines the major elements and challenges for the introduction of a new or an improved public transportation system. Drawing upon experiences in Europe and North America, the paper reviews the current state of practice and covers issues related to the use of public transportation services. The paper concludes by illustrating the case of the city of Auckland, New Zealand. These papers illustrate the range of research directions to improve the urban transportation planning process. Some focus on the methodological framework, others on broader and more connected considerations, better understanding of travelers’ choices, and issues that ought to be carefully considered in new initiatives or improvement schemes. We trust that, collectively, these two special issues serve to broaden the perspective on the new approaches for urban transportation planning. It is our hope that they will inspire and stimulate new research initiatives and efforts in this still evolving field.

Procedures for planning multi-leg journeys with fixed-route and demand-responsive passenger transport services

This paper describes journey-planning procedures designed for use in a traveller information system covering fixed-schedule and demand-responsive public transport modes. The task is to construct a sequence of journey-legs to meet a traveller’s requirements with the least possible generalised cost, subject to time-window and other constraints. A journey may be carried out in a single leg by walking or by taking a taxi all the way from the origin to the destination, or by a sequence of one or more legs carried by public transport services sandwiched between walked segments connecting an initial pickup and final setdown stop. The public transport services may include fixed-route modes such as bus and train, and demand-responsive services running between fixed points. The main planning procedures are a high-level request-broker and a branch and bound procedure to handle multi-legged journeys; the request-broker also invokes a fleet-scheduling module to obtain bookings on demand-responsive services. The paper describes planning conditions, the planning procedures, and reduction techniques that are used to obtain acceptable computational performance. Tests with simulated demand suggest that the procedures are well suited for use in a real-time traveller information system.

Recruitment, Selection, and Retention of Personnel at North Carolina Community Transportation Systems: Findings and Recommendations from a Study

The hiring and the retention of personnel have been a long-standing issue in the public transportation industry. This involves finding and recruiting potential employees, selecting and hiring the most qualified candidates, training and developing employees, monitoring performance and retaining employees, and reducing excessive turnover and absenteeism. While human resources topics have typically been investigated at urban transit systems operating fixed-route services, hiring and retention have not been studied extensively at smaller rural transit systems operating demand-responsive transit services. This research focused on such rural systems and on the various factors that most impact on the issue at nine North Carolina community transportation systems. This effort included various human resources policies and practices such as recruiting, selecting, compensating, training, evaluating, and motivating. Practices at the nine case study systems and recommendations to improve policies and procedures are described.

The evaluation of demand responsive transport services in Europe

Over the last decade Demand Responsive Transport (DRT) services have grown in popularity for several reasons including: the shortcomings of conventional regular bus and taxi services; shortcomings of special transport services; and new developments in community transport. Traditional dial-a-ride services have often been criticised because of their relatively high cost of provision, their lack of flexibility in route planning and their inability to manage high demand. The potential for overcoming these limitations may be realised through the introduction of telematics-based DRT and this has been widely demonstrated, for example, in recent research funded by the European Commission (e.g. the DGXIII-funded SAMPO and SAMPLUS projects). This paper provides an introduction to the concept of telematics-based DRT services and presents the results of the evaluation of a set of DRT technologies and operations at urban and rural sites across Europe. The paper offers discussion in terms of the key issues that influence the introduction of DRT services.

The Demand Responsive Transport Services: Italian Approach

Direct-dial services are an excellent connection between traditional forms of collective and private transport. They are the answer to development of transport demand for homogeneous travel, non-homogeneous travel, and to the growing need for travel from specific consumer classes such as the elderly and the disabled. Four separate operative levels may be identified for demand responsive transport services: 1) fixed itineraries and stops with possibility of access through booking; 2) fixed itineraries with possibility of detours within specific boundaries; 3) service with free routes between fixed points; and 4) service with free routes between free points. This paper describes the aforementioned transport systems and analyzes their efficacy, productivity, and consumer ratings using some case examples from Florence and Genoa, Italy.

Better Transportation Services for Older Persons

Improvements to public transportation services are being made, or can be made, to offer better public transportation services for older travelers. Communities in which some of the most forward-looking ideas have been applied were examined. A number of short-term, low-cost improvements have been shown to be beneficial, but new perspectives are also needed. In the long run, multiple types of services, offered at varying prices, are needed to replace the “one size fits all” approach to public transportation with options that riders could choose on their own to fit the specific demands of individual days and trips. Shared-ride, demand-responsive services, dispatched and controlled through advanced technologies, could provide higher levels of service than now available and at higher levels of productivity and cost-effectiveness. Frequent, comfortable, affordable, spontaneous service to a wide variety of origins and destinations over a wide range of service hours is what seniors desire. A serious challenge for the public transportation industry will be finding ways of providing such services while collecting revenues that cover their costs. A key finding of this research is that the transportation service attributes most highly valued by older riders are not markedly different from those valued by other transit riders, so that improvements that would best serve older riders will also attract significant numbers of other riders.

Demand responsive services in hierarchical public transportation system

An advanced public transportation system called the local initiative for neighborhood circulation (LINC) is proposed and the realization of its usage is investigated. LINC effectiveness and efficiency comes from its utilization of a transit-station-oriented system with elimination of present bus stops. LINC has three levels of services. Level 1 is the regional trunk line service with high-speed and high-capacity service provided by the regional transit authority. Level 2 is the intercommunity express bus service with frequent and reliable service provided by the metro transit system. Level 3 could have many forms to serve within the community and to/from level 1 or level 2 transit stations. Our study is limited to the dial-a-ride service, which operates door-to-door service as a public taxi, provided by small buses and/or vans. This paper will address the optimization problem of the dial-a-ride service. A genetic algorithm scheme is applied to its optimization and proper solutions are obtained as a result.

Multi-modal and demand-responsive passenger transport systems: a modelling framework with embedded control systems

The LITRES-2 modelling system provides a framework for investigating the performance of urban passenger transport systems, with particular attention to demand-responsive transport modes and traveller information technologies. The modes covered include conventional timetabled services (buses, trains etc.), taxis (both single- and multiple-hire), and other demand-responsive services. Tables of estimated aggregate demand are disaggregated so as to produce a stream of fully-articulated travel-requests. Individual requests are resolved as single- or multiple-leg journeys, through the use of request-broking and journey-planning modules that seek to minimise travellers' generalised costs. Journey-legs allocated to demand-responsive modes are handled by a fleet-scheduling module which includes provision for “instantaneous” as well as advance-notice bookings, and for contingent situations such as breakdowns and passenger no-shows. The fleet-scheduling and journey-planning modules are designed as embedded control systems and are intended for use in real-time as well as modelling applications. The paper describes the main analytical and procedural components of LITRES-2, and assesses some methodological issues arising from experience in recent planning studies. The system appears to be well suited for use in modelling situations where the critical issues are concerned with the supply rather than demand side of transportation activity.