Ambulance & EMS Preemption

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. 

Not all preemption systems are equal

With the Eliminator this happens well before reaching the intersection due to its ability to communicate at a greater distance than other systems. The goal of the Eliminator is not to turn the light green upon arrival 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 process (preamble) can begin up to 2.8 miles (if necessary) before the ambulance reaches the intersection. At busy intersections the system typically starts the process at .7 to 1.0 miles from the intersection. This gives plenty of time for a safer preemption that also flushes traffic. Additionally because the Eliminator uses FEMA recommended 900 MHz FHSS (frequency hopping spread spectrum) private encrypted radio network the system is precise and secure.

2.4 GHz Radio WiFi based systems are not the solution

Although any Radio/GPS system eliminates LOS issues that exist with Optical based systems and increase range, some systems use 2.4 ghz (WiFi) and therefore only have a max range of 2,500 feet (.47 miles/.76 km). At busy intersections and/or high traffic areas starting the process of changing the light to green 4 tenths of a mile away will not result in a clear intersection. Many times traffic is congested 4 tenths of a mile or more. Traffic lights do not immediately turn green when preempted, first the light in the opposing direction must SAFELY go from green, to yellow, and then finally to red allowing a green light in the preempted direction. This process can take 5 to 15 seconds. Preemption is also not allowed to override pedestrian crosswalk timers which can increase the preamble time further.

Cellular Systems are not the solution

Just as with Radio/GPS based systems, cellular based preemption systems also solve the line of sight (LOS) problem, however these cellular emergency vehicle preemption systems bring a new set of problems.

  • Cellular brings monthly fees. Imagine a coin operated box attached to the signal and every preemption having a cost. More specifically and costly, every communication, resulting in a preemption or not, will have a cost. 
  • In large emergencies (mother nature, terrorism, etc.) the cellular network always go down. So when you need your preemption the most it will not be functional. 
  • Are Cellular networks 100% reliable? Anyone with a cell phone knows they are not. From lag/delay to network overload you do not want your green light being dependent on a network shared by everyone else around you. 
  • Although some cellular systems may offer a radio backup, it is just that, a backup. If the radio backup worked well then it wouldn't be the backup. When these systems are proposed in a bidding process they are required to include 10 or even 15 years of unlimited cellular data.
  • Since cellular based preemption lacks precision the preemption timings will not be precise or consistent which degrades performance and benefit. Recently one large city tested a cellular preemption system and found it took up to 10 seconds to release a preemption. This can result in the preemption being held for a tenth of a mile or more after the EV clears the signal.

It is also worthy to note that using 2.4 GHz and Cellular go against FEMA recommendations for Preemption Systems.1.

The Eliminator is the full Solution without compromise

The Eliminator has a range of 13,500 feet (over 2.5 miles/4 km). Where this really matters is when you factor “obstructions” such as curves in the road, valleys and hills, buildings, trees, and other obstructions including the semi or bus in front of you. Obstructions reduce the effective range of a system. Obstructions turn 4 tenths of a mile of other GPS Preemption Systems into 3 or 2 tenths of a mile. One solution is to buy repeaters (also called range extenders). Not only is this more equipment to buy/maintain but also more points of failure. Additionally, extenders create latency that slow up the process. Further these range extenders must be mounted up high and need power, this can require additional poles and power line runs. FEMA recommends preemption systems that use the 900 MHz band instead of 2.4 GHz or optical line of sight (LOS) systems.2

Multiple Agencies sharing a Preemption System

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 apparatus on the other hand is much easier to stop, but may reach much higher speeds. That is why the Eliminator treats each department and class (Heavy Duty/Light Duty) 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 department and class.

The Eliminator preemption system 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).

Why are Response times Important?

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

Reducing the number of lights/siren responses

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.

Traffic Signal Preemption for Emergency Vehicles, A Cross-Cutting Study, Putting the “First” in “First Response”, FHWA (2006), page 3-3,Download PDF

U.S. Fire Administration, Emergency Vehicle Safety Initiative, FA-336/February 2014, page 94,Download PDF 

U.S. Fire Administration, Emergency Vehicle Safety Initiative, FA-336/February 2014, page 80, 

U.S. Fire Administration, Emergency Vehicle Safety Initiative, FA-336/February 2014, page 79, 

Traffic Signal Preemption for Emergency Vehicles, A Cross-Cutting Study, Putting the “First” in “First Response”,, FHWA (2006), page 3-1.




GPS Preemption Compatible with Optical

Do you already have an Optical Preemption System or Infrared Preemption system or commonly referenced by a brand name such as Opticom ®, Emtrac ®, Tomar ®, Strobecom ® or MIRT ®? Upgrading to a GPS Traffic Signal Preemption System is affordable and simple.

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FireRescue1 Industry Article

Could traffic preemption reduce fire response times and save lives? Once overlooked as expensive and impractical, signal preemption has come a long way since the 1970s

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FDIC 2019

Come visit our booth at FDIC (Fire Department Instructors Conference) April 8th - 13th to learn more about our Traffic Signal Preemption System. Booth 9153 Near Pierce Booth, click below for picture of booth location.

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Fire Departments

As the call comes in and your department is focused on digesting and learning the circumstances of the emergency and the scene while enroute, traffic should not be a major consideration. Today�s electronically distracted drivers have made the opposite even more true. Motorists already respond to the presence of an emergency vehicle differently but often distracted drivers do not react at all.

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Police Departments

The Eliminator Emergency Vehicle Preemption (EVP) System provides specific features designed for Police Departments. Most EVP systems use ETA or GEO windows to define when or where preemptions occur. However Police Cars typically travel at a higher rate of speed than Fire and EMS, specifically faster than the larger vehicles such as Engines, Tankers, and Ladder Trucks.

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EMS

From the moment an emergency run begins, there is 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.

Learn More