System Status Management (SSM) is the fluid deployment of ambulances based on the hour-of-the-day and day-of-the-week in order to match supply, defined as Unit Hours of Utilization (UHU), with expected demand, expressed as calls for service, in the attempt to provide faster response by locating ambulances at “posts” nearer their next calls. While the practice is still not unanimously embraced by all services, it has a sound foundation both in the research literature dating back to the 1980’s as well as in practice today. Experience has shown that ambulance response times can be dramatically decreased using this type of dynamic deployment, but it is also recognized that it is possible to reduce performance when these techniques are not applied properly. The direction of the results of a system implementation are typically influenced by the system design, competence of the managers creating the plan, and commitment of the workforce in implementing it. Therefore the best practice is a simple and straightforward implementation that will show positive results quickly. This methodology ensures a positive return on investment along with garnering the necessary buy-in from staff to make the project a success.
In his article, “System Status Management – The Fact is, It’s Everywhere“, published in the Journal of EMS (JEMS) magazine back in 1989, Jack Stout explained the concept of SSM and tried to dispel certain myths. Based on foreseen Geographic Information System (GIS) technology and even general computing capabilities of that time, it was quite logical to assume in his Myth #2 that “no matter how thoroughly the response zone concept is fine-tuned in practice, it cannot be made to cope effectively with the dynamic realties of the EMS environment.” But systems implemented today around the US are capable of calculating dynamic response zones in a small fraction of a second while even being based on time-aware historic driving patterns making a truly dynamic system status management process a reality. A practical and proven example of a dynamically functioning system status management application is the Mobile Area Vehicle Routing and Location Information System, or simply MARVLIS.
The following Slideshare presentation does an excellent job of telling the story of why and how the system works: