Demand Responsive Transport
The Concept

During the last few years Demand Responsive Transport (DRT) services have shown important advantages and benefits in several European cities and regions including Ireland.  These services are complimentary to conventional, scheduled passenger transport serving dispersed mobility needs, low demand hours or areas of low population.

DRT can include a range of features:

  • Local buses on routes with some flexibility.
  • Dial-a-bus services between stops or door-to-door.
  • Special needs transport.
  • Community Transport.
  • Shared taxis and car pooling.
  • Some forms of Park and Ride, including those with advanced place booking.
  • Car sharing and organised lift giving.

The system can be defined as one that is adapted to meet the known needs of users, typically on a trip-by-trip basis, incorporating the following core functions:

  • A ‘knowledge-acquiring’ function to understand the actual demand, or at least the relevant variations on expected demand responsive transport.
  • An analysis function to determine what action to take in response to this known demand responsive transport.
  • A dispatching function to communicate the changes to assignment and operating personnel.

In some cases there may be a default route with variations applied as required.  In other cases the service may be determined entirely from the specific demand for that trip.  It is important to remember that the characteristics of both DRT and conventional transport services vary dramatically depending on whether the location is urban, peri-urban or rural in nature.

DRT has at least one degree of freedom within any specific trip.  This allows the dispatch centre or the operator to alter the service offer in response to the actual demand.

The three main dimensions in this respect are: the route taken, the timing of the service and the vehicle used.

The most fundamental options relate to the route taken by the vehicle.  The main options are presented below in order of increasing levels of flexibility:

  • Offer a fixed route as default, serve points off the route on request, and return to the original route at the same point – all points on the fixed route are always served.
  • Offer a fixed origin and destination pair and perhaps pre-determined intermediate points and section(s) of the route.  Serve points off the route on request, and return to the fixed route at the optimal position.  Some points on the normal route might not be served therefore booking is needed.
  • Offer a fixed route service on the trunk section of the route, but have flexible routing at one or both ends of the route, thus providing a local collection/distribution role.
  • Have a number of defined stops/collection points, and generate an optimal routing based on the specific trip demand.
  • Generate the service from the requested origins and destinations on a free routing basis.

A further level of flexibility can be achieved by adapting the timing of the offered service.  The main options include:

  • Advancing or delaying the departure time for the service.
  • Pick-up or set-down at a time specified by the user.
  • Adjusting the timing to meet/wait for another transport service for transfers.
  • Choosing whether or not to operate a specific trip.
  • Time period for switching between conventional and DRT operating mode.

Vehicle Assignment
The vehicle assigned to carry out the trip can be altered for cost, operational or facilities reasons.  The main options include:

  • Upsizing/downsizing vehicles to match the expected number of passengers on the outbound or return trip.
  • Assigning a smaller or more robust vehicle when required to operate on smaller roads (e.g. in rural areas) or in traffic-calmed areas.
  • Assigning a more appropriate vehicle/driver if the handling of packages/documents is offered as part of the service.
  • Where there are very few passengers for the planned trip, pass the work to a taxi firm and do not operate the (mini) bus trip.
  • Assigning vehicles with wheelchair lifts (and trained drivers) or other special facilities on demand so that not all vehicles in the pool need this equipment.

Based on the above operational choices, different types of service models can be implemented.  Often, these fall within four basic model types (see Figure below).


Regardless of the type of service model implemented and the underlying operational choices, DRT services are organised around four main steps:

Office Dispatchers using system

1.     User calls the Travel Dispatch Centre
2.     Recording of journey parameters

  • Service negotiation between the TDC operato and the User

  • Communication to Driver

The flexibility of DRT schemes is made possible with the help of Information and Communication Technology (ICT).  This might include software modules for booking and dispatching, communication modules for exchange of data with vehicles and automated vehicle location systems.

Overall, the main elements of this would include:

  • A Travel Dispatch Centre which has several integrated software systems to support its management.  i.e. trip booking, vehicle dispatch or data management.
  • A communication system, based on public or private long-range wireless telecommunication networks, supporting communication and information exchange (both data and voice) between the TDC and the vehicles.

XDA Unit

  • On-board systems installed on vehicles to

provide driver support during vehicle
operations i.e. dynamic journey information,
route variations, passenger information,
driver/dispatcher messages, e.g. Aplicoms/XDA Units.

A range of communication systems including telephone and internet to provide the user with several different methods of contacting the Travel Dispatch Centre. 

FLIPPER Project (Interreg 1VC)

Throughout Europe the challenge of providing a cost effective integrated public transport service is seen as an essential prerequisite to reducing pollution and congestion whilst encouraging sustainable economic growth.  The traditional fixed route services are ideal for clustered travel demand areas but the changing habitation patterns and nature of work activities in today’s society have created different mobility needs to which the conventional transport has become neither suited nor cost-effective.  In the last few years Flexible Transport Services (FTS) have proved to be an advantageous solution to the provision of public transport services.  By providing various forms of intermediate services, FTS are complementary to the conventional passenger transport modes and usually serve no scheduled mobility needs, either in low demand time periods or in weak demand areas.  Given this flexibility, FTS are suitable to serve niche market customers and different citizens’ groups (e.g. people with disabilities and elderly, students, tourists, etc).

The FLIPPER project is financed by Interreg IVC programme and started officially in  September 2008.  It addresses a key factor of eco-sustainable and competitive development and social cohesion of European areas and regions, through the investigation, experience exchange, good practices transferring and profitable co-operation on FTS, in relation to mobility in cities, rural areas and small towns.  By capitalising on real results, experiences and good practices gained in previous EU site applications and EU Projects, FLIPPER aims at establishing a Knowledge Transfer Network among different EU areas and authorities in the domain of FTS.  Moreover the FLIPPER objective is to achieve capability-building, environmentally sustainable and innovative solutions in the Public Transport domain, by evaluating the viability and real impacts and by gathering the good practices identified at site level. 

There are 11 partners within the the FLIPPER group (representing local authorities, transport operator companies and universities) from 9 EU regions. 

  • Public Transport Authority of Bologna, Italy (project co-ordinator)
  • Mobility Authority of Florence Metropolitan Area, Italy
  • The Aristotle University of Thessaloniki - Transport Systems, Greece
  • The Institute of Transport Studies, Austria
  • The Municipality of Purbach in Burgenland, Austria
  • University of Aberdeen-Centre for Transport Research, Scotland
  • Municipality of Volos, Greece
  • Livorno Transport Operator, Italy
  • Mallorca Train Service, Spain
  • Almada City Council, Portugal
  • Ring a Link, Kilkenny, Ireland

The project outcome and durable results will include technological, operational and organisational experiences exchanging on FTS at regional and international level to improve the effectiveness of policies for regional development, cohesion and co-operation; disseminating good practices and establishing a network for improving accessibility, transport services and life quality.