Ambulance & EMS Preemption

http://collisioncontrol.net/files/TrafficSignalPreemptionforEmergencyVehiclesCrossCuttingStudy.pdf From the moment an emergency run begins, there’s potential for an even greater disaster – colliding with another vehicle enroute to the scene of the emergency. This often results in that vehicle and its occupant(s) becoming an additional emergency incident to address. Many cities have experienced an increase in collisions with emergency vehicles at intersections, but emergency vehicle preemption has been shown to effectively reduce the probability of these collisions by giving ambulances the right of way. 

With the Eliminator this happens before reaching the intersection due to its ability to communicate at a greater distance. The goal of the Eliminator is not to turn the light green upon arrival (at a maximum range of less than 1/2 mile with optical and most other GPS systems), but to turn the light green well in advance of the emergency vehicle’s arrival, also allowing for pedestrians to safely cross in opposing directions and for those vehicles stopped in direction of the emergency vehicle’s path to safely clear the intersection prior to the ambulance’s arrival at the intersection. With the Eliminator, this preemption “preamble” can begin up to 2.8 miles (if necessary) before the ambulance reaches the intersection.

Ambulances travel at different speeds than other emergency vehicles. Fire trucks that may be fully loaded with tens of thousands of gallons of water will not be nearly as nimble as an ambulance for example. A police car on the other hand is much easier to stop, but may reach much higher speeds. That is why the Eliminator treats each “class” of emergency vehicle differently, and each intersection can be programmed to preempt based not only on the emergency vehicle’s distance and speed, but also its class as well.

It also resolves conflicts among different emergency vehicles who may be competing for the same traffic signal. Typically cities choose to prioritize preemption events based on the vehicle’s ability to stop (or lack thereof). Fire trucks are typically given priority over ambulance/EMS, which in turn are usually given priority over Police (which are typically more agile and are able to stop more quickly than Fire or Ambulance).

For EMS personnel, getting prompt medical attention to a patient can often increase the patient’s chances of survival. According to the American Heart Association, for every minute that lapses between a cardiac arrest and defibrillation, the probability of survival is reduced by 7 - 10%1. After 8 minutes, there is little chance of survival. In trauma care, seriously injured patients who arrive at an operating room of a trauma center within the first 60 minutes after a crash have a much greater chance of survivability compared to those who arrive within 90 minutes. In rural areas, timely notification, response and decisions regarding medical care prior to transport can save lives.2

There exist multiple studies comparing ambulance response times with and without the use of lights and sirens. The majority of these have demonstrated that although response times are faster with lights and siren, the time saved had no significant impact on patient outcome, except in cardiac arrest and obstructed airway cases. The Emergency Medical Services Outcomes Project (EMSOP) identified seven clinical conditions that account for 65 percent of all adult EMS transports and seven that account for 85 percent of all pediatric transports. Of these conditions, only cardiac arrest — the second least frequent of all the conditions — appears to require rapid EMS response (Sword RA, Cone DC., 2002).3 In the rest of the situations, drivers should use a modified emergency response - using warning devices to clear a reasonable path to the incident, but not operating the apparatus with the sense of urgency used when responding to a true emergency.4

The Eliminator’s “ON MODE” feature has the unique ability to facilitate such a “modified” emergency response (See Fire Chief Danny Sink Video for more information on this and other features) By preempting traffic signals WITHOUT the use of lights or siren, the chances of the apparatus being involved in a collision are dramatically reduced, while the travel time is similarly reduced by 14% - 23%.5 This eliminates excessive out-of-service times that might prevent them from otherwise being available to respond to a true emergency. These are just a few of the Eliminator’s many unique features that directly impact the safety and efficiency of EMS personnel on a day-to-day basis.