1.1 Introduction
Intelligent Transportation Systems (ITS) are complex systems which require a systematic basis for their planning and deployment processes. In view of this need, the European ITS Framework Architecture (FRAME) was set up to support ITS development and to foster their roll-out at the Member States by facilitating system integration, fostering interoperability, avoiding vendor lock-in situations and promoting the standardization of functionalities, interfaces and data models. The fast technological evolution and the growing interest in Cooperative Systems based on V2X communications unveiled new requirements uncovered by the existing architectures, leading to alternative approaches by certain research projects, which ended in an extended version of the FRAME architecture and complementary standardization processes to fulfil the needs posed by the connected vehicles and road infrastructures.
This chapter will outline the reference architectures conceived for ITS planning and deployment in Europe, their evolution through the inputs provided by major ITS projects and initiatives and some experiences from the authors when facing the definition of ITS architectures through our involvement in research projects, by following different approaches.
1.2 FRAME: The European ITS Framework Architecture
An ITS Architecture sets a framework to plan, analyse, define, deploy and integrate Intelligent Transportation Systems, allowing at the same time understanding of their business, organizational and technical implications. It is commonly depicted as a high-level design showing the structure and operation of a certain system in a given context, which can be used as a basis for further low-level design phases.
An ITS architecture integrates three main elements:
- the functions that are required for ITS;
- the system partitioning into logical or functional entities such as subsystems, modules or components, where these functions reside;
- the information and data flows that connect these functions and physical subsystems together into an integrated system.
When talking about ITS architectures in Europe, the key reference is the European ITS Framework Architecture (often referred to as FRAME). The FRAME Architecture was created as an attempt to provide a common approach across the European Union so that the implementation of integrated and interoperable ITS can be planned. Its main objective is to foster the deployment of ITS in Europe and for that purpose, it defines a framework providing a systematic basis for ITS planning, easing integration between multiple systems and ensuring interoperability and consistency of information.
1.2.1 Background
The FRAME Architecture was created by the project KAREN (Keystone Architecture Required for European Networks), funded by the European Commission under the Fourth Framework Programme in the area of Transport Telematics and first published in October 2000. The need to keep the architecture up to date was soon identified, and this entailed a huge maintenance effort. During the following years (2001–2004), projects FRAME-NET and FRAME-S, funded by the European Commission under the Fifth Framework Programme, carried out this task successfully. As a result, not only did the architecture evolve but also user needs were updated, a methodology supported by computer-based tools was defined, a centre of knowledge created and the FRAME Forum was established so that users and stakeholders could exchange advice and experiences. Since 2006, due to the growing expectations created by the so-called Cooperative Systems based on V2X communications and strongly supported by the European Commission, the FRAME Architecture entered an adaptation process to provide support to the new set of user needs and requirements posed by connected vehicles and road infrastructures, which were not covered by the original version. The project E-FRAME (Extend FRAMEwork architecture for cooperative systems), funded by the European Commission under the Seventh Framework Programme, addressed this need between 2008 and 2011. As a result, the FRAME Architecture version 4 supporting Cooperative Systems was released in 2010.
Since the time of the KAREN project, the FRAME Architecture has been adopted and successfully used in different ways by many nations, regions, cities and projects throughout Europe. Reference best practices can be mentioned such as the French national ITS Architecture (ACTIF), the Italian national ITS Architecture (ARTIST) and other adopting nations such as Austria (TTS-A), the Czech Republic (TEAM), Hungary (HITS) and Romania (NARITS). In addition, specific ITS Architectures have been created in the UK including one for Transport for Scotland and another for the County of Kent, while Transport for London intended to use FRAME Architecture to plan its future ITS deployments. In some cases it has also been used by R&D projects such as VIKING, EASYWAY, COOPERS and MoveUs among others, and even in pre-commercial procurement programmes such as CHARM-PCP, participated by the Highways Agency (UK) and Rijkswaterstaat (the Netherlands).
1.2.2 Scope
Strictly speaking, FRAME is not always considered as an architecture, but more a framework targeted to help European countries and regions planning their own ITS architecture tailored to their particular needs. In this sense, the experience is quite similar to the one in the USA, where the main objective of the National ITS Architecture has been to guide the ITS development and deployment throughout the country at the federal, state and local levels.
The most recent release of the FRAME Architecture (version 4), published in 2010 with the updates from the E-FRAME project, covers the following ITS areas:
- Electronic Fee Collection;
- Emergency Notification and Response – Roadside and In-Vehicle Notification;
- Traffic Management – Urban, Inter-Urban, Simulation, Parking, Tunnels and Bridges, Maintenance, together with the Management of Incidents, Road Vehicle Based Pollution and the Demand for Road Use;
- Public Transport Management – Schedules, Fares, On-Demand Services, Fleet and Driver Management;
- In-Vehicle Systems – including Cooperative Systems;
- Traveller Assistance – Pre-Journey and On-Trip Planning, Travel Information;
- Support for Law Enforcement;
- Freight and Fleet Management;
- Support for Cooperative Systems – specific services not included elsewhere such as bus lane use, freight vehicle parking;
- Multimodal interfaces – links to other modes when required, e.g. travel information, multimodal crossing management.
When dealing with an ITS architecture, and also with FRAME, a number of different views can be considered:
- User Needs, which are always the starting point and collect the expectations to be covered by an ITS deployment and its associated set of services. The identification of these needs may involve different stakeholders such as public transport or freight operators, system integrators, national/regional governments and every kind of traveller.
- Functional Viewpoint, which defines the functionality to be provided by the ITS in order to meet the User Needs, usually structured into functional areas and further divided into specific functions. This is represented as Data Flow Diagrams containing the functions and showing how they relate to each other, to data stores and terminators, as well as the data that flows between them.
- Physical Viewpoint, which describes how functions can be grouped into physical components allocated to modules or subsystems. Hence, detailed specifications for each component can be produced.
- Communications Viewpoint, which describes the communications links needed to support physical data flows. Once the functionalities have been allocated to physical modules, the location of the Functional Data Flows can be inferred and also the information flow between modules, thus representing communication channels. At this level, communication specifications can be produced and the use of an existing standard, or even the need to define a new one, may be agreed.
In addition to the main architectural views, use of the FRAME Architecture enables other kind of activities such as a Deployment Study, showing how to deploy the systems and communications derived from the ITS Architecture and the way t...
