Road Network Operations
& Intelligent Transport Systems
A guide for practitioners!

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ITS Infrastructure

ITS works when the supporting infrastructure – which includes roads, ITS devices, vehicles, terminals, management centres – communicate with each other and with users. For a road authority, the ITS infrastructure components can be divided into four different categories: field, centre, vehicle and telecommunications.

  • field devices include roadway devices, such as:
    • traffic cameras and sensors
    • parking management systems which include real time parking occupancy detectors
    • roadway payment system such as automated toll collection system which includes radio-frequency identification (RFID) receivers
    • security monitoring devices such as surveillance cameras and intrusion detectors
    • signal controllers and traffic lights
  • centre infrastructure, such as:
  • a traffic management centre coordinating real time roadway operation functions – for example, incident management and traffic rerouting.
  • vehicle infrastructures, such as:
    • emergency vehicles responding to a severe traffic incident
    • mini-buses, buses, trams and coaches – for example, the vehicle location systems that support real-time scheduling and travel information
    • maintenance and construction vehicles deployed in a work zone
    • taxis and other vehicle fleets used as probe vehicles to determine traffic characteristics
  • telecommunications infrastructure, which can be:
    • wired, such as a fibre optic cable network
    • wireless, such as cellular or WiMAX technology

The diagram below shows how field, centre and vehicle infrastructures connect to each other. Centres may communicate with each other and with field devices through wired or wireless technology. Vehicles communicate with centres and field devices through wireless infrastructure.

Figure 1: ITS Infrastructure Components

Importance of ITS Architecture

ITS Architecture plays an important part in Road Network Operations. The ITS architecture is a primary element in ITS planning. Two types of ITS architecture are typically defined:

  • a high level architecture (which can be either a Framework or Model Architecture), often for publicly funded ITS deployments in a national, regional or local area
  • a low level architecture (project-level) for specific ITS deployments, such as a Regional Traffic Control Centre

A high level ITS architecture provides the framework for the deployment of ITS across a wide geographical area with multiple jurisdictions and different stakeholders participating in common or inter-dependant operations. The architecture specifies how the various ITS components interact with each other to address the transport problems. It provides the basis for planning, designing, deploying, maintaining and integrating systems to realise transport objectives.

An ITS architecture does not specify the ITS scheme design in detail. Nor does it require a particular design approach. Instead it does the important job of specifying the performance criteria that the system components must satisfy – and defines a general framework from which several alternative designs or design options may be developed. These distinct designs will conform to the common ITS architecture. (See What is ITS Architecture?)

An ITS architecture should define the following:

  • functions: that describe what the ITS system has to do to meet the user requirements – such as “collecting traffic data” or “providing incident information”
  • physical entities: the locations where ITS functions are to be performed – such as a traffic management centre or traffic signal controllers
  • interfaces and information flows: the interfaces showing data exchange connectivity (existing or proposed) and the information flows between physical entities. For example, an interface between a traffic management system and roadway traffic detectors might be two-way:
    • in one direction, speed data flows from the traffic detectors to the traffic management system
    • in the opposite direction, a sensor control command flows from the traffic management centre to the traffic detectors


Maximum benefit from ITS requires interoperability and interchangeability of systems between regions and within a region. Interoperability refers to the condition where different types of systems can interface with each other to meet the system’s functional requirements. Multiple brands of a device on the same communications channel is an example of interchangeability. One of the primary goals of ITS is to integrate a variety of previously independent systems to minimize redundancy and maximize efficiency – so adhering to ITS and other industry standards will satisfy the interoperability and interchangeability requirements and support future efficient system expansion. Legislative requirements to comply with industry and ITS standards in any ITS project will support interoperability, interchangeability and future cost-effective expandability of the system. (See ITS Standards)

Technological Change

Technology is changing at a rapid pace and this trend is expected to continue indefinitely. ITS builds on technology-based services – and the pace of technological change is an important consideration in planning and deployment. Three issues must be addressed when considering changes in technology for any ITS applications. These are: upgrade, legacy systems and systems integration.


With technology changing rapidly, even during the course of an ITS project, it is important to anticipate the possibility of system upgrades. Newer technologies can improve the performance of an already deployed system – and may require a decision on whether to upgrade the system or replace it. Where it is possible to look ahead, work planning and design should allow for the possibility of upgrades so they can be accommodated efficiently and without technical complexity. A possible disadvantage is that system upgrades may require highly skilled professionals to operate and manage the new systems in the future.

Legacy Systems

As new systems and upgrades come on line, they must be integrated with earlier “legacy” systems. The challenge lies in making the new systems interoperable. ITS architecture can show where and how established legacy systems will need to interface with new systems to deliver the desired (integrated) system functionalities and performance. A field evaluation plan for testing the interoperability between a legacy system and new systems will provide the basis for testing the integrated system after deployment.

Systems Integration

Systems integration is about how different systems are connected together so that they can perform the desired tasks in an optimal way. ITS requires different types of hardware and software (which may come from different manufacturers and be implemented at different times) to be integrated to satisfy user requirements.

Problems – that can pose a significant challenge to systems integration – technically and because of the cost, are:

  • using hardware and software that are unique to one supplier
  • system interfaces that do not follow industry and ITS standards

Adhering to established industry and ITS standards and the use of open architecture will support future cost-effective systems integration.

Advice to Practitioners

A system-wide outlook at the inception of a project will help develop a deployment plan that supports a cost-effective implementation strategy:

  • an ITS architecture that takes account of user needs regionally and nationally will support cost-effective project development locally, even when the projects take place at different points in the timeline. This is because the entire system, with its subcomponents and interdependencies, are considered at the outset of each project

If the design provides for interchangeability of components it will encourage competition and allow scope for future improvements in cost, design, functionality and safety (See ITS Architecture):

  • ITS technologies provide multiple options to address particular user needs or requirements. Availability of many options for the same set of requirements (for example electronic tolling equipment) may promote different products in different regions that are not compatible or interoperable with each other. A common architecture and a set of standards that have evolved from a common architecture can solve the problem of interoperability

ITS architecture can show where standard interfaces will bring significant benefits:

  • it does not assume the use of specific ITS technologies or components. It should instead, be generic, to allow freedom for system developers to design what they see as optimum solutions – meeting appropriate standards and accommodating the interfaces needed for interoperability and likely future extensions

ITS architecture shows how different stakeholders are connected with one another through data exchange:

  • ITS architecture helps to identify institutional interdependence that can assist in reaching regional goals. It can serve as a guide on how different agencies can share the same ITS infrastructure to achieve their own institutional objectives

The existence of an ITS architecture can assist in integrating systems coming on-line in different phases:

  • it is not possible to meet all user requirements at any one time, with one project. ITS projects are usually completed in phases

ITS architecture can support security services related to disaster response and evacuation, freight and commercial vehicles, hazardous materials, rail, transit and transport infrastructure:

  • in addition to supporting transport services, ITS architecture can contribute to regional and national security


Further Informations

Bloomington/Monroe County USA, Regional Intelligent Transportation Systems Architecture, 2008.

Chowdhury, M. and Sadek, A., Fundamentals on Intelligent Transportation Systems Planning, Artech House, Boston, MA, 2003.

Fries, Chowdhury and Brummond, Transportation Infrastructure Security Utilizing ITS, John Wiley & Sons, 2008.

U.S. Department of Transportation, National ITS Architecture, (accessed on December 1, 2013).

Reference sources

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