Demand Responsive Transport Services Research Articles

On dynamic demand responsive transport services with degree of dynamism

The operation of a demand responsive transport service usually considers advanced and real-time requests. Previous studies focused on solution algorithms for routing and scheduling challenges of a pickup and delivery problem with time windows, but the operational issues of the overall system performance under a partially dynamic environment have not been investigated. In this article, we explore the operating efficiency of a dispatching system with a degree of dynamism (i.e. a ratio of dynamic requests). It is found that a dispatching system incurs higher transportation costs and accepts fewer requests when the request arrivals are partially dynamic, as compared to static or fully dynamic scenarios. Operational policies are derived for the dispatcher to avoid the inefficient range of degree of dynamism if future demand can be anticipated.

Identifying potential market niches for Demand Responsive Transport

In principle, Demand Responsive Transport services, or paratransit in US nomenclature, offer public transport providers a more flexible and potentially more cost effective delivery option than conventional bus services, particularly in situations of low demand. However in practice, there are many examples of promising DRT schemes that have failed, for a number of reasons. One recurring feature appears to be that the DRT operation introduced is not appropriate for the market served. This is due to a lack of knowledge as to what markets may be susceptible to DRT.This paper aims to help address this research gap by drawing on the findings of two qualitative research data collection efforts, exploratory in-depth interviews and focus groups, each including industry experts. Using a marketing framework, developments at the micro, meso and macro levels are explored to determine the circumstances necessary for developing ‘successful’ DRT market niches. Implications for managerial practice include integration of services to improve market penetration and in responding to market development opportunities aimed at the general public. Technology plays the greatest role in responding to market niche demand, primarily in enabling flexible booking and providing real time information, supporting market development, product development and diversification opportunities.

Transport poverty meets the digital divide: accessibility and connectivity in rural communities

Rural communities face a range of challenges associated with accessibility and connectivity which apply in both the physical and virtual sphere. Constraints in rural transport infrastructure and services are often compounded by limitations in the development and resilience of technological infrastructures. In this context there is significant disparity between urban and rural communities.This paper will examine the context for accessibility and connectivity in rural communities highlighting key transport and technology challenges. It also explores barriers and opportunities to bringing together transport and technology solutions to enhance rural accessibility and connectivity. This is an area where current understanding is weak as most research has been focussed on urban environments. The paper focuses specifically on two issues of current research; firstly, the role of information and associated technologies in supporting rural passengers on public transport, secondly, the use of technologies to support flexible and demand responsive transport services in rural areas.

An evaluation of the user characteristics of an open access DRT service

The successful provision of Demand Responsive Transport (DRT) in Europe, Australia, UK and the US has been addressed in several substantial studies and projects. The general finding of these studies is that DRT is a suitable transport solution in particular areas and can deliver social inclusion and community building objectives. Existing research confirms that DRT is particularly useful for connecting isolated communities and population groups to essential services such as healthcare and is cost-effective in terms of contributing greatly to community wellbeing. However, many existing DRT services are still not performing to their true potential, and many of them could not be viable as commercial services. The aim of this study is to develop greater understanding of DRT services from the passengers’ perspective using a case study of LinkUp in Tyne and Wear, one of the most successful DRT schemes in the UK. The paper has two key objectives: (a) to critically review, in the context of the detailed case study the general characteristics of the selected DRT scheme; and (b) to analyse and interpret the findings from a detailed survey of users (who are predominately elderly and female) with regard to passenger characteristics, their attitudes and perception of the service and their suggestions for improvement.

User Needs for Urban Car Travel

The results of in-depth interviews with focus groups on user needs for urban car travel in the Helsinki, Finland, metropolitan area are presented. The interviews concentrated on determination of the instrumental motives for dependence on the car by a sample consisting of various types of urban travelers who described their three most typical trip types in three situations used to guide the discussion: (a) when the car is the only possible travel mode option, (b) when the car is the best travel mode option, and (c) when disadvantages to the use of a car exist. Findings were used to reveal attribute and attitude patterns. A description of user needs was then formulated on the basis of these patterns. Two significant motives for use of a car were insufficient public transport connections and the need for temporal flexibility. The analysis indicated that a mass demand-responsive transport (DRT) service can be used to respond to the main user needs detected. A new mass DRT concept is therefore proposed, and the means by which it could affect urban travel is analyzed nonempirically. Nevertheless, some user attributes support use of a car. As a counterbalance to these attributes, however, there are perceived disadvantages to use of a car. The results argue for serious consideration of whether to apply the proposed DRT concept to mass transit in urban areas.

An adaptive insertion algorithm for the single-vehicle dial-a-ride problem with narrow time windows

The dial-a-ride problem (DARP) is a widely studied theoretical challenge related to dispatching vehicles in demand-responsive transport services, in which customers contact a vehicle operator requesting to be carried from specified origins to specified destinations. An important subproblem arising in dynamic dial-a-ride services can be identified as the single-vehicle DARP, in which the goal is to determine the optimal route for a single vehicle with respect to a generalized objective function. The main result of this work is an adaptive insertion algorithm capable of producing optimal solutions for a time constrained version of this problem, which was first studied by Psaraftis in the early 1980s. The complexity of the algorithm is analyzed and evaluated by means of computational experiments, implying that a significant advantage of the proposed method can be identified as the possibility of controlling computational work smoothly, making the algorithm applicable to any problem size.

Role of automatic vehicle location systems and localisation accuracy in freight transport: an analytical estimation of gained operational times

This study concerns the application of automatic vehicle location systems (AVLSs) for the control and management of fleet of vehicles whose regular routes are random, that is, with origins and destinations so numerous and variable that they cannot be predefined. Typical examples include road shipments, pick-up and delivery services and express couriers, demand responsive transport services and public utility services (gas, water etc.). Specific reference is made to transport of goods but analogous observations may be valid for passenger transport. The average response time of the mobile unit depends on (i) the accuracy of the AVLS adopted; (ii) the configuration of the fleet within the territory where it operates; (iii) a number of operative parameters, among which are the size of the operative area, the number of vehicles employed, the average time that they are in use, their average speed and the average time taken to perform the service. The results of two specific models provide average response times which can be compared in transport operations carried out with and without the use of an AVLS. If we abstract the equations derived from these, we obtain a quantity Δt, which measures the reduction in response time resulting from the adoption of an AVLS. The relevance of the results is related to the role of accuracy, integrity and continuity of the future Galileo system for transport location services.

From mode choice to modal diversion: A new behavioural paradigm and an application to the study of the demand for innovative transport services

We analyse past research efforts that focus on modal diversion in the transport sector, as opposed to the classical mode choice concept, showing the added value of this alternative framework that emerges from the existing scientific literature. The modal diversion paradigm is then used to assess the relative importance of the technical performances of transport services on one hand and of the subjective factors of its potential users on the other, when forecasting the use of a new means among a group of white-collars working in a French research institute. We quantitatively show that multimodal habits and cognitive attitudes have an importance that is in general not negligible for this group, compared to that of the transport services performances, even if only these latter are routinely considered by engineers and planners. Beyond this, we find that the role of self-related factors further increased when the group was less familiar with the technological background and the subsequent operation of the new system, such as in the case of demand responsive transport services.

Using GIS to visualise and evaluate student travel behaviour

Using GIS to evaluate travel behaviour is an important technique to increase our understanding of the relationship between accessibility and transport demand. In this paper, the activity space concept was used to identify the nature of participation in activities (or lack of it) amongst a group of students using a 2 day travel–activity diary. Three different indicators such as the number of unique locations visited, average daily distance travelled, and average daily activity duration were used to measure the size of activity spaces. These indicators reflect levels of accessibility, personal mobility, and the extent of participation, respectively. Multiple regression analyses were used to assess the impacts of students socio-economic status and the spatial characteristics of home location. Although no differences were found in the levels of accessibility and the extent of participation measures, home location with respect to a demand responsive transport (DRT) service was found to be the most important determinant of their mobility patterns. Despite being able to travel longer distances, students who live outside of the DRT service area were found to be temporally excluded from some opportunities. Student activity spaces were also visualised within a GIS environment and a spatial analysis was conducted to underpin the evaluation of the performance of the DRT. This approach was also used to identify the activity spaces of individuals that are geographically excluded from the service. Evaluation of these results indicated that although the service currently covers areas of high demand, 90% of the activity spaces remained un-served by the DRT service. Using this data six new routes were designed to meet the coverage goal of public transport based on a measure of network impedance based on inverse activity density. Following assessment of public transport service coverage, the study was extended using a spatial multi criteria evaluation (SMCE) technique to assess the effect of service provision on patronage.

Older people and local public transit: Mobility effects of accessibility improvements in Sweden

Several transportation factors concerning older and disabled people are under transition in Sweden at present. By the year 2010, the public transit system must be fully accessible for all passengers. The present survey studied older people, in order to assess the perceived travel opportunities. Questionnaires were sent to a sample of older citizens (75+) in three Swedish mid-sized municipalities. The general conclusions were that even though older people show appreciation of the existing travel opportunities, there was evidence for restricted mobility for some sub-groups of these older people, due to various perceived barriers. These groups have few optional modes, and despite various accessibility measures, special transportation services – the mandatory demand-responsive transport service – continues to provide crucial mobility. Hence, there is more to be done regarding accessibility and usability in public transit for older people. Further studies have to clarify reasons for bus travel cessation. Even larger efforts have to be put into accessibility improvements, in particular intermediate transit solutions in order to meet the regulations and policies.

Flexible transport services: A new market opportunity for public transport

The term Demand-Responsive Transport (DRT) has been increasingly applied in the last 10 years to a niche market that replaces or feeds (usually via small low floor buses or taxis) conventional transport where demand is low and often spread over a large area. More recently, the concept of DRT as a niche market has been broadened to include a wider range of flexible, demand-responsive transport services and is increasingly referred to as Flexible Transport Services (FTSs). The contention of this paper is that well-implemented FTS has the potential to revitalise bus-based public transport services which are traditionally based on fixed networks with variable geographical coverage and levels of service.

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.

Reconstruction of regional transportation services in rural area and methodologies

The objective of this paper is to discuss regional transportation service reconstruction and methodologies for that as a solution for the issue of expanding areas without public transportation services in rural areas. Transportation services that meet rural need could be reorganized by focusing a range of livelihood. In this paper, on the basis of the range of rural livelihood, regional transportation services are classified to three categories (community transportation, inner municipality transportation, and inter-municipality transportation). Further, as measures to secure regional transportation services, integration of transportations, DRT (demand responsive transport), and community pick-up service are proposed.

Demand responsive transport: towards the emergence of a new market segment

This paper focuses on recent British experience with telematics-based Demand Responsive Transport (DRT) services in rural areas. In recent years, the ability of DRT concepts to provide efficient, viable transport services has been greatly enhanced by the use of transport telematics as demonstrated in a variety of environments across Europe. The success of British local authorities in winning substantial funding under the Rural and Urban Bus Challenge programmes for the implementation of DRT has resulted in widespread interest in flexible forms of transport. It is thus timely to evaluate the impact of this substantial investment. Drawing on the experience of a number of UK schemes, the paper assesses the reasons for the new-found success of what is becoming a relatively well-accepted mode by concentrating on a variety of factors including: service characteristics (particularly route flexibility, flexibility of booking method and pre-booking regime), emerging markets and the overall contribution of DRT to increased social inclusion and intermodality. Impediments to the development of DRT services are highlighted. The paper also discusses current research into the next generation of DRT services and concludes by identifying some key issues for policy-makers concerned with the future implementation of DRT services.

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.

A Project to Implement a Demand Responsive Transport Service (DRTS)

This paper presents a new project to implement a Demand Responsive Transport System (DRTS) in the city of Firenze, Italy, within the area of Campi Bisenzio. The project is operated by ATAF (Azienda dei Trasporti dell'Area di Firenze - Firenze Area Transit Company), within the framework of the Italian National Research Program on Transportation Systems (Progetto Finalizzato Trasporti 2) of the Italian National Research Council (Consiglio Nazionale delle Ricerche - CNR) and of SAMPO (System for Advanced Monitoring of Public Transport Operations), an international project within the European Programme on Telematics Applications (DGXIII). In particular, the paper deals with the methodological aspects of the project, i.e., the general approach that has been devised to define the procedures according to which the system is operated.

The application of microcomputer and on-line graphical display technology to demand-responsive transportation services

Scheduling and dispatching a fleet of vehicles to respond to ongoing requests for transportation to and from various points in an urban area can be a complex proposition. Human controllers face an unmanageable number of scheduling possibilities. A strictly mainframe computer-based system would require elaborate computer algorithms, and high investment cost. This paper discusses the development of a low-cost interactive microcomputer color graphics system that displays vehicle and demand information and performs routine tasks while freeing the human dispatcher for creative decision-making. The system is designed for dispatching demand-responsive vehicles for pickup and delivery of passenger and express packages.

A model system for forecasting patronage on demand responsive transportation systems

Demand-responsive transportation (DRT) systems represent a broad class of public transportation options characterized by spatial and/or temporal flexibility in serving demand. These systems offer the potential to provide service in lower density areas. This paper presents a model system which provides DRT system designers with a behaviorally consistent and validated patronage forecasting procedure. The model system consists of three components: a work trip demand model; a non-work trip demand model; and a DRT service model. These components are applied in an equilibrium framework. The demand components of the system are disaggregate demand models. The work trip model forecasts modal split, while the non-work model forecasts trip frequency, time of day, mode and destination choice. The service model forecasts both wait time and ride time. The model was estimated on data from Rochester, New York, and validated against data from Davenport, Iowa and La Habra, California. Total daily trips by DRT appear to be forecast ±20–30%. A sketch planning model was also developed and validated against six other DRT sites with errors of a similar magnitude. The model system can analyze options such as varying the vehicle fleet or service area over the day, using differing vehicle sizes, alternate pricing policies, and improving vehicle speeds.