EM02-Emergency Routing Transaction Set Diagram

1. The Emergency Management Subsystem can keep its mapping system current by subscribing to a map update service. Map updates are provided on request (map update request) to support preparation of a suggested route to Emergency Vehicles.
   
   
2. The Traffic Management Subsystem provides current road and traffic conditions (road network conditions). Current work zone information, current asset restrictions (e.g. dimensional constraints for bridges, tunnels and overhead clearances), and roadway maintenance status are also provided by the Maintenance and Construction Management Subsystem. This information can be used later in preparing suggested routing for Emergency Vehicles.
   
   
3. The Emergency System Operator tracks the location and status of emergency vehicles and other resources, monitors incident status, traffic and road conditions, and the operation of the system itself (emergency operations status). The system operator controls the dispatch and routing functions performed by this process (emergency operations inputs).
   
   
4. The Emergency Management subsystem can request status from one or more Care Facilities (care facility status request). The returned information (care facility status) can be used to decide to which Care Facility to route an Emergency Vehicle carrying an incident victim.
   
   
5. An individual Emergency Vehicle can also directly request status from one or more Care Facilities (care facility status request). The request is initiated by the Emergency Personnel as part of emergency personnel inputs. The status information that is returned to the Emergency Vehicle(care facility status) and then passed along to the Emergency Personnel (as part of emergency personnel information presentation) can be used to decide to which Care Facility to bring an incident victim.
   
   
6. En route, an Emergency Vehicle can report patient status to the Care Facility. The report can be initiated by the Emergency Personnel (as part of emergency personnel inputs) or come from equipment on the Emergency Vehicle.
   
   
7. An Emergency Vehicle tracks its location (position fix) and periodically reports its actual position and status to the Emergency Management subsystem dispatch function (emergency vehicle tracking data). Using information collected earlier (see 1 and 2 above), the Emergency Management dispatch function can directly determine a best route for the Emergency vehicle. In special circumstances such as during disasters and evacuations when normal routes are not available, the Emergency Management Subsystem may request a route (emergency route request) from the Traffic Management Subsystem, which then provides the route (emergency routes). In addition to providing the route, the Traffic Management Subsystem can manage traffic to better support emergency vehicle progress along the suggested route. Whether the route is computed by the Emergency Management Subsystem or the Traffic Management Subsystem the suggested route is provided to the Emergency Vehicle (suggested route) and relayed to Emergency Personnel (emergency personnel information presentation).
   
   

There are two options in the National ITS Architecture for signal preemption to be effected for Emergency Vehicles. The first is Center-to-Center based, and the second is based on Field-Vehicle Communications between the Emergency Vehicle and Roadway. Both approaches have their advantages.

8. Center-To-Center based Signal Preemption. The Emergency Vehicle subsystem reports its progress to an incident to the Emergency Management subsystem (emergency vehicle tracking data). The Emergency Management subsystem reports the anticipated route and progress along that route to the Traffic Management subsystem (emergency traffic control request). The Traffic Management subsystem can adjust the signal timing plans (signal control data, signal control status) to accommodate the Emergency Vehicle by either adjusting the timing so that the Emergency Vehicle has a green signal when it arrives at an intersection, or the intersections can "go flashing red" until the Emergency Vehicle is known to have passed. Traffic Management can notify Emergency Management as to whether they can expect signal preemption or not (emergency traffic control information). The advantage of this operational concept is that for regions that have already deployed AVL (Automated Vehicle Location) on Emergency Vehicles, and have already deployed closed loop signal control, the marginal cost to deploy this system is very small (possibly only requiring a center-to-center information channel). It may, however, require a higher level of reliability for these systems than was required for their original deployed purpose.
   
   
9. Alternatively, an Emergency Vehicle may use Field-Vehicle Communications with Roadway equipment at or near the intersection to preempt the signals (local signal preemption request) as the Emergency Vehicle approaches. The Roadway equipment may optionally notify the Traffic Management subsystem that it has been preempted (request for right-of-way). This may be used by Traffic Management personnel to determine if the preemption capability is working appropriately, if it is being "abused" by any particular Emergency Vehicles, and correlate preemption actions with congestion due to de-synchronization of the traffic signal system caused by asynchronous preemptions.
   
   
10. The Emergency Vehicle may use short range communications to warn other vehicles in the vicinity (emergency vehicle alert) so that the vehicles can warn their drivers of an approaching emergency vehicle.