ITS rely on communications supplied by telecommunications operators offering a variety of hardware and communications media – to provide the platform for ITS applications. Examples include, fibre optics, the internet, WiFi, 3rd and 4th generation cellular phone networks together with computer servers and devices. The hardware and communications are hosts for the ITS applications and handle the physical movement of data and information.

ITS technical standards are concerned with how communications are adapted for a specific application – standardising specialised ITS data content and governing communications interfaces. These include protocols and message sets which enable smooth data flow and information exchange among components and subsystems:

• protocols, such as TCP/IP for the Internet, specify the structure for transmission of data messages and the details of message formats, and describe how to handle error conditions
• message sets (multiple messages and data sets), usually defined in a data dictionaries (a standardised format that allows meaningful exchange of information between subsystems). For example, for information exchange related to incidents – standards are needed to code a certain number of message elements that will describe unambiguously the location (such as the road segment number) and the type of incident (fire, injury)

There are some cases where ITS-specific communications standards have been developed – most notably in electronic tolling and other vehicle-to-roadside technologies. In this case, the standardisation of frequencies and modulation techniques ensures that communications hardware and software interoperate correctly. (See Standardisation & Interoperability)

ITS standards can also be categorised by their geographic scope – according to whether they have been established at the local, regional, national, international or global level. Not all standards need to be global. For instance, for practical reasons, most ITS applications developed for commercial vehicle operations need only be capable of operating at the continental level (such as within China, Europe, North America). Global ITS standards for commercial vehicle operations are not feasible at the moment – and they are not essential, so long as heavy goods vehicles/lorries do not operate in more than a single continent. By contrast, cargo identification systems need to be compatible across modes of transport and must meet global standards – if they are to be capable of following freight movements between continents and ensure proper security checks along the way.

ITS standards can also be categorised according to the nature of the agreement – by which they become established as standards. ITS standards may be:

• de facto standards – established by a dominant manufacturer/supplier and achieving market acceptance through commercial success
• consensus standards – developed through formal procedures in official standard development organisations – or emerging from unofficial industry collaboration to agree on standards outside the official bodies and their formal processes
• regulated standards – established by governments (in the form of a regulation), either because other methods have been unsuccessful or because they need to be interoperable across borders

Regulation can also be used to accelerate and harmonise deployment of ITS. An example of this approach is the European Commission’s ‘ITS Directive’. (See http://ec.europa.eu/transport/themes/its/road/action_plan/) It mandates that new ITS deployments in the EU comply with standards specified under the Directive – in four priority areas:

• optimal use of road, traffic and travel data
• continuity of traffic and freight management ITS services
• ITS road safety and security applications
• linking the vehicle with transport infrastructure

ITS communications standards were initially designed to enable connectivity between vehicles and fixed infrastructure. (This included:

• wide area communications protocols – such as the CALM (Communications Access for Land Vehicles) suite of standards developed by the International Standards Organisation (ISO) – which allow vehicles to maintain connectivity across a variety of communications technologies
• dedicated short range technologies optimised for applications such as Electronic Toll Collection (ETC)

More recently, a focus on safety-related communications has led to the extension of this standards work in two areas of communication:

• vehicle to infrastructure (V2I)
• vehicle to vehicle (V2V)

These standards are needed for the deployment of cooperative systems which depend on highly reliable, very low latency communication interactions (time delay) between vehicles and the roadside. For example – vehicle to roadside communications used in applications to assist in collision avoidance and traffic flow optimisation. (See Warning and Control)

As vehicle connectivity has increased, the ITS standards community has recognised the need for standardised interfaces and interactions between the vehicle and:

• the Internet of Things (IoT) – including nomadic devices such as smartphones and tablet computers (See Data and Communications)
• emergency and disaster management support services (See Emergency Response)
• security and traffic control frameworks. (See Security Planning)

An early priority for standardisation in ITS was the exchange of data between traffic management centres and roadside infrastructure.

In the USA, a standards suite for road network operators and traffic authorities is the National Transportation Communications ITS Protocol (NTCIP). It has been updated continuously since its development in 1997. Its standards aim to facilitate data transfer:

• between traffic management centres and roadside equipment (for example, between traffic controllers and dynamic message signs)
• between control centres
• the European DATEX (Data Exchange) standard was originally created as a traffic and travel data exchange mechanism for traffic control and information centres – but has evolved (DATEX II) to support applications requiring access to dynamic traffic and travel information. (See Other Monitoring Sources – Data Exchange)

A new set of standards which enable data transfer to and from connected vehicles and devices is being developed through a number of coordinated international efforts. (See New Forms of Mobility) For example:

• the Basic Safety Message/Cooperative Awareness Message – allows connected vehicles to share information in support of safety applications
• vehicle probe data is used for a variety of applications including crowd-sourcing of transport network information during disaster situations