The full benefits of ITS can be realised only if the many stand-alone traffic and travel information systems are integrated within a region. However, integration is not as straightforward as some might expect.
The first practical issue in regional deployment has to do with its scope. In order to define a “region” in which ITS applications are to be integrated, one has to consider integration at different levels – domestic integration within a country, international integration with trade partners or with geographical neighbours. For example, Mexico has problems of domestic integration among its seven regions because standards for ITS-related subsystems and levels of available information are very diverse among these regions. Internationally, Mexico has faced problems integrating with its trade partners within NAFTA on the one hand because Canada and US have more developed ITS technologies, and integrating with other Latin American states on the other hand because their ITS are less developed.
The size of the region will determine the level of interoperability that is required. The appropriate scale of deployment depends on specific applications. International cargo identification and freight transport can benefit greatly from interoperability among nations for the sake of efficiency and security. Standard toll collection devices for a region are more important for trucks moving freight across a sub-continent than for passenger vehicles that stay in the same metropolitan area most of the time. This has led to the suggestion of ETC - based on GPS for trucks, and DSRC for cars. Cross-border traffic information has become important in Europe as many vehicles frequently travel between countries. Other ITS applications work best on a smaller scale - such as local traffic management and control.
People and organisations have different objectives, motivations and attitudes - and their diversity is greater the wider the region to be integrated. Although most institutional problems could be alleviated by legal and contractual arrangements, building consensus requires seed funding. Conditional funding for regional deployment - as often provided in Canada - has been found to be beneficial where no money is available from government unless and until consensus is reached.
If used appropriately, system architecture can help high-level decision makers to understand the functioning of ITS and to cooperate in its deployment. (See ITS Architecture) Ideally, where an architecture is used - a regional architecture should be developed to support regional deployment in a way which is consistent with the national architecture. In the absence of a national architecture, the development of a regional architecture at a lower level may be sufficient. Using this bottom-up approach, a regional architecture can evolve from either a “concept of operations” or from technical specifications based on regional objectives.
Voluntary harmonisation and interoperability can also be achieved by specific regional ITS projects oriented towards this goal - and involving "all" regional partners. Good examples include the European EasyWay action, which has, with European Commission support, produced ITS Deployment Guidelines for many ITS services - and the Asia-Pacific ITS Guidelines aiming to harmonise the national ITS Master Plans for sustainability. (See Deployment Guidelines and Asia-Pacific ITS Guideline)