Terminology
Various definitions of Intelligent Transportation Systems (ITS) have been put:

• New information and communications technologies are finding exciting applications in urban transport. Also called "Transport Telematics". (ERTICO, Europe)
  
• A broad range of diverse technologies, which holds the answer to many of transportation problems. ITS is comprised of a number of technologies, including information processing, communications, control, and electronics. Joining these technologies to our transportation system will save lives, save time, and save money. (ITS America)
  
• The application of advanced sensor, computer, electronics, and communication technologies and management strategies - in an integrated manner - to increase the safety and efficiency of the surface transportation system. (ITS Assist, UK)
  
• A broad-based term which used to describe developments in communication and computing technologies applied to transport services generally. (ITS Australia)
  
• The application of advanced and emerging technologies (computers, sensors, control, communications, and electronic devices) in transportation to save lives, time, money, energy and the environment. (ITS Canada)
  
• ITS offers a fundamental solution to various issues concerning transportation, which include traffic accidents, congestion and environmental pollution. ITS deals with these issues through the most advanced communications and control technologies. (ITS Japan)
  
• An innovative transportation system that may be able to secure a cheap and safe transportation environment as well as an efficient operation by connecting up-to-date skills including electronic, communications, and control systems to existing transportation systems such as road, railway, airway, and sea transportation. (ITS Korea)

The term ITS is elastic and capable of broad or narrow interpretation. ITS covers all transport modes and is understood to include consideration of the vehicle, the infrastructure, and the driver or user, interacting together dynamically.

Information is at the heart of ITS. Most ITS tools are based on the collection, processing, integration and/or supply of information. Whether offering real time information about current conditions of a network, or on-line information for journey planning, ITS tools enable authorities, operators and individual travellers to make better informed, more "intelligent" decisions (ERTICO, 1998b).

Application fields of ITS
ITS covers broad development fields, and is or will be implemented in various schemes, but the fields of ITS can be identified by user services which represent what the system will do from the perspective of the user. The concept of user services allows system or project definition to begin by establishing the high level services that will be provided to address identified problems and user needs.

In USA, DOT (Department of Transport) and ITS America is focused on the development and deployment of a collection of inter-related user services in the national ITS program, called the National ITS Architecture which provides a common framework for planning, defining, and integrating ITS. Following table presents the 32 user services which formed the basis for the National ITS Architecture development effort, grouped into eight bundles for convenience.

In Japan, user services are set by allocating users for each of the nine different development fields in accordance with individual users' needs and conditions under which these needs arise by MLIT (Ministry of Land, Infrastructure and Transport).

In Europe, ERTICO offers ITS Toolbox, which aims to be a first source describing how ITS can be used to attain transport policy and business objectives. The Toolbox describes a number of ITS application tools and contains supplementary information about the selection of appropriate tools for particular objectives and about the benefits of integrated ITS tools. Tools are grouped into six areas (ERTICO, 1998b):

Technology

The concept of ITS is based on advanced communication technologies, that are used in the fields of each user service or application tool. The main developing technologies are (Japanese MLIT, ERTICO (1998b), IHT (1997)):

• Advanced cruise-assist highway systems (AHS) aims to reduce traffic accidents, enhance safety, improve transportation efficiency as well as reduce the operational work of drivers.
• Automatic incident detection (AID) aim to detect incidents automatically and quickly in order that the problem can be dealt with and the roads returned to normal operation as soon as possible. The detection system could be CCTV using image processing.
• Electronic data interchange (EDI) is a standardised form of electronic communication used mainly for electronic commerce and document interchange.
• Automatic vehicle location (AVL) systems are needed in many ITS application. There are many technological possibilities, such as GPS, vehicle-beacons, map matching and dead reckoning.
• Electronic toll collection (ETC) system is non-stop payment transaction at a tollgate utilizing bi-lateral radio communication between roadside unit and on-board unit. ETC is almost same technology as Electronic Road Pricing (ERP).
• Radio data system - Traffic message channel (RDS-TMC). RDS is a one-way broadcast, point-to-point transmission system. No information is sent back from the vehicles to the RDS service provider. With RDS it is possible to transmit additional digital information alongside normal FM radio transmission by superimposing a silent data channel. RDS-TMC provides a common European facility for transmitting dynamic and event related traffic and weather information.
• Real-time driver information systems and route guidance are covered in a separate section.
• Smart cards are a generic term for a credit card size device that contains several semiconductor devices including memory and an associated microprocessor. Data can be written to be read from and stored upon the card and manipulated in conjunction with other devices such as a smart card reader. Smart cards have been used for public transport payment contact and contactless.
• Variable message signs (VMS) are covered in a separate section.
• Weather data monitoring systems are designed to monitor current meteorological conditions. The information is then used to forecast poor weather. They enable network managers to act in good time, informing drivers of likely bad weather and initiating appropriate winter maintenance or emergency procedures.