The rationale behind the development of ITS is the need for high efficiency and quality in new and innovative transport services. The goal of these services is either to meet a certain need for the movement of people and goods – or to supply a specific endeavour (or activity) with the correct amounts of its necessary components at the right time and at the right location. These activities are called transport and logistics respectively. By implication, the design of these services will include modern information and communication technologies (ICT) for the exchange of information in real time and the result is an “intelligent” transport system.
From their everyday activities, people identify needs for movement between specific locations and become travellers. They engage in trip planning and, if successful, a trip plan will be created by linking a sequence of transport options to serve the journey – if necessary based on different transport means. These transport options can either be chosen from available information (in timetables, for example) or can be made known to someone (who can organise such options) as dynamic demands on transport. These travel demands and travel patterns are today normally captured by surveys and observations on a yearly basis to inform the production of static timetables.
The planning of a journey includes a matching exercise between the total travel demand and the future availability of vehicles to serve that demand and provide the transport service. The matching will be successful only if no disturbances in the traffic process occur and no characteristics of an open-loop control system are evident.
When technical systems such as ITS are put into a societal context, complexity emerges. The systems have to be designed in a cost-effective, efficient, safe and environmentally acceptable way. These objectives require design methods which make it possible to cope with system complexity.
ITS usually involves several human decision makers – and all the decision-making processes which require information about the ITS environment must be considered. Integration of network operations, transport processes and stakeholder perspectives is necessary. Analysis, design and evaluation of this complexity, and its impact on modern solutions for transport services, must be performed adequately.
Activities (or processes) in society which make use of a technical infrastructure and communications networks will be influenced by a large number of decision-makers and stakeholders. They are often geographically dispersed, have contradictory goals and act with different time horizons. In consequence, description and analysis of the interaction between technology and people in a specific class of systems can become so complex that specialist tools and techniques may be required. Expert help should be sought where necessary.
Three highly interrelated perspectives - networks, processes and stakeholders - can be usefully identified and, if combined in an operational way, can be helpful to the analysis, design and evaluation of ITS solutions.
The network perspective is focused on the links, nodes and elements for transport and communications which, when brought together, form the physical network and its structure. The use of technologies (and especially ICT) is important and adds complexity. This can be dealt with by breaking down the network into subnets or subsystems.
The process perspective is focused on the interaction between network components and the different flows of traffic or communications that can be identified in the processes. The dynamic characteristics are related to the transmission and transformation of information and related information channels. A matching between the time horizons of the control processes and the speed of information exchange is crucial for acceptable performance.
The stakeholder perspective is highly related to how ITS supports decision-making. The stakeholders have to interface with the processes and the networks by means of work stations, control panels, mobile or other in-vehicle units. The interface designs must be adapted to the mental models of the processes used by the stakeholders in their tasks. An appropriate filtering of information has to be introduced if the stakeholders are not to be overloaded, or disturbed by other processes or events outside of their control. A hierarchy of abstraction levels can be established. (See Users of ITS and Stakeholders )