This subsystem resides in an emergency vehicle and provides the sensory, processing, storage, and communications functions necessary to support safe and efficient incident response. The subsystem represents a range of vehicles including those operated by police, fire, and emergency medical services. In addition, this subsystem represents other incident response vehicles including towing and recovery vehicles and freeway service patrols. The Emergency Vehicle Subsystem includes two-way communications to support coordinated response to emergencies in accordance with an associated Emergency Management Subsystem. Emergency vehicles are equipped with automated vehicle location capability for monitoring by vehicle tracking and fleet management functions in the Emergency Management Subsystem. Using these capabilities, the appropriate emergency vehicle to respond to each emergency is determined. Route guidance capabilities within the vehicle enable safe and efficient routing to the emergency. In addition, the emergency vehicle may be equipped to support signal preemption through communications with the Roadway Subsystem.
The Emergency Vehicle Subsystem (EVS) is the communications lifeline that connects emergency personnel in the field with emergency dispatch, other emergency personnel, and other resources that support emergency response. The EVS handles potentially sensitive information, must "operate through" and be available in distressed environments, and is exposed to numerous threats including eavesdropping (disclosure), unauthorized access or control, and disruption of services. Although confidentiality is a concern, the most critical security objectives for EVS are availability and integrity - the services and information provided by EVS must be available and accurate so that incident response is not degraded. Although the EVS provides the same basic driver communications, tracking, and routing functions that are provided by the other fleet vehicle subsystems, these functions are frequently safety critical for this subsystem since they directly impact the ability to provide an effective response to emergencies, which in turn impacts public safety.
The EVS represents a wide range of vehicles including police cruisers, command vehicles, various types of fire apparatus, service patrol vehicles, ambulances, towing and recovery vehicles, and many different specialized response vehicles. This collection of vehicles may have very different security requirements, depending on the functions supported, the data that is stored, and the mission criticality of the services provided. For example, maintaining confidentiality of police vehicle locations is a public safety concern and frequently a key security objective. Tow vehicle locations are generally not a public safety concern, but tow truck operators may still want to prevent unauthorized vehicle location disclosure for business reasons. Finally, the current location of a service patrol vehicle may not be considered to be particularly sensitive.
There are also other variables that impact security that are independent of vehicle type. For example, initial EVS data services will supplement voice communications that frequently will continue to carry all mission critical information. The security requirements for these initial implementations might be less robust until the agency gains experience with the EVS data services and begins to rely on them for mission critical information. As the role of the data services evolves and expands, the security requirements and the systems themselves must be revised so that mission critical systems are available and reliable when they are needed most. The specific analysis of the security objectives, threats, vulnerabilities to those threats, and appropriate security services to address the vulnerabilities should be undertaken for systems associated with the EVS.