ISO 22951 will make interventions by emergency vehicles faster and safer 

A new ISO standard will help to ensure that police cars, fire engines and other emergency vehicles will arrive at the emergencies to which they have been dispatched as quickly and safely as possible.

ISO 22951:2009, Data dictionary and message sets for preemption and prioritization signal systems for emergency and public transport vehicles (PRESTO) standardizes messages in preemption signal systems for emergency and public transport vehicles. By providing a common infrastructure, the standard aims to promote the dissemination of such systems.

Preemption signal systems control traffic signals – for example, by prolonging green lights,  or shortening red lights – on the basis of information on the location of emergency vehicles, their speed, destination and direction of travel at an intersection so that emergency vehicles can cross an intersection quickly and safely. At the same time, information on the passage of emergency vehicles can be transmitted to other vehicles and pedestrians in order to avoid collisions.

ISO 22951 thus addresses systems that use priority signal control functions to help emergency vehicles operate. This type of system comprises a traffic management centre, in-vehicle units, roadside communication units, and roadside units. Public transport vehicles such as buses may also be connected to priority signal controls.

The scope of standardization includes message sets and a data dictionary related to communications between:

• A roadside communication unit and each in-vehicle unit
• A roadside communication unit and other roadside units
• In-vehicle units and roadside units.

The benefits offered by implementing ISO 22951 include the following:

• Reduction in the response time of emergency vehicles,
• Early resolution of accidents and improvement of arrest rates (in the case of police interventions at crime scenes)
• Support for speedy rescue activity and improvement of lifesaving rates
• Reduction of the number of traffic accidents associated with en-route emergency vehicles
• Improvement public transport services by minimizing disruption.

Mr. Koorosh Olyai, Convenor of the ISO working group that developed ISO 22951, comments: "When emergency or public transport vehicles cross-borders, the potential for road safety hazards and public transport delays become even greater. In order to avoid such situations and make it possible to use a common infrastructure for all emergency vehicles regardless of the country where they operate, an International Standard is indispensable. ISO 22951 includes examples of PRESTO at work in different countries."

ISO 22951:2009, Data dictionary and message sets for preemption and prioritization signal systems for emergency and public transport vehicles (PRESTO), was developed by ISO/TC 204, Intelligent transport systems, working group WG 8, Public transport/emergency.