Crossing Guard - Fire Chief Magazine

Crossing Guard

Excerpts from article in the November 2007 issue of Fire Chief Magazine (published with permission)

BY Dave Gross, President/CEO Collision Control Communications, Inc.

Many cities across the United States have experienced an increase in emergency vehicle accidents. These accidents can be attributed to departmental training issues, misunderstanding of the right-of-way laws for emergency vehicles, better soundproofing of vehicles, and increased traffic volumes, among other factors.

But departments also have experienced an increase in the number of apparatus-to-apparatus collisions at intersections. Today's technology can help prevent these accidents, assuming a firefighter's seatbelt is properly used, and control traffic signals from inside the cab with preemption technologies.

Most of these technologies use an infrared beam to trigger traffic signal preemption. Using these line-of-sight preemption technologies has its drawbacks. Anything that obstructs visibility will similarly diminish the ability of these systems to reliably preempt traffic signals. Weather phenomena such as fog, rain, snow and dust storms can reduce the range of these systems. Other obstacles may include large vehicles such as semis and buses. Curves in the roadway, buildings, bridges or foliage also may lie along a direct line of sight between an approaching emergency vehicle and traffic signals.

GPS preemption systems recently have been introduced to overcome line-of-sight concerns, but these bring a different set of problems inherent in global positioning. GPS users probably know that GPS requires satellite triangulation. This necessitates contact with satellites for the unit to know where it is. These systems must then be taught which surface areas of the roadway should trigger preemption. This can become a problem in the downtown areas of many metropolitan cities where one or more skyscrapers may hinder immediate satellite acquisition.

But now radio technology can be used to solve some of the nagging problems that have plagued firefighters and other emergency response personnel for quite some time. Battalion Chief Dudley Taylor and the Indianapolis Fire Department are testing and evaluating a new RF collision-avoidance technology at Fire Station 13 in the downtown area. That station's primary engine has the system installed and the station is awaiting the installation of the system to one of its aerial trucks. This RF-based system, designed by professors at Indiana University and Purdue University, will warn emergency-vehicle drivers of impending collisions with other similarly equipped vehicles. At the same time, this system also will protect from collisions with passenger vehicles by preempting traffic signals through the use of radio waves.

It is often difficult for the occupants of one emergency vehicle to hear the siren of another because of their own. And it is impossible to see around some blind intersections. Use of this radio technology would warn an emergency vehicle driver of an impending collision up to three-quarters of a mile in advance.

“The Bells & Whistles” (below) show one device, called the “Eliminator” that uses RF technology. Picture this device installed in the emergency vehicle within view of the driver or one of the crewmembers. When the technology senses a potential collision, an alarm gives audible and visual information relative to the threat. Distance to collision sensitivity can be set from a few hundred feet up to 4,000 feet. In the event of a collision impending directly from the right, for example, an alarm sounds and is followed by a prerecorded voice that announces a “collision alert at 3 o'clock.” The volume can be adjusted for the audible alarm and voice commands. At the same time, one of the 60 L.E.D.’s on the circular display of the collision avoidance screen will light to showing the direction of the threat relative to the direction of travel of the vehicle.

When traffic signals are preempted, the status light on the face of the device changes from red to green. The voice command also announces the preemption status. If the traffic signal is preempted in a rig's favor, the voice command announces “preemption active.” In the event where two or more emergency vehicles are competing to preempt the same traffic signal, vehicles that aren't given first priority of the intersection will again have the alarm sound, with the prerecorded voice saying “preemption pending.” The collision avoidance display also will show the direction of approach of all other emergency vehicles approaching the intersection.

On arrival at the scene, it is often necessary to exit the vehicle expediently and begin rendering assistance without having to remember to turn off the traffic signal preemption feature. When the three-position mode toggle switch is flipped up to auto mode, preemption automatically commences when the light bar is activated. The device automatically relinquishes preemption of nearby traffic signals to other emergency vehicles that may be approaching the scene. This is accomplished within the device that also monitors the transmission and parking-brake status. This allows the device to determine whether the emergency vehicle is stopped in traffic, still requiring preemption, or has arrived on scene, when preemption should be deactivated.

The technology has been adapted for use in other emergency vehicles as well. Often an unmarked police unit would need use of the preemption feature of the technology without announcing its presence by light bar or siren. In this case the mode switch can be switched to the manual position that will constantly preempt traffic signals until switched off.

The intent of all preemption systems is to help emergency vehicles respond to the scene as quickly and safely as possible. Preemption systems will continue to proliferate into all emergency vehicles to a point where the number of emergency vehicles responding to a given event increases the possibility for an accident between responding vehicles. Technologies like the one being tested by the Indianapolis Fire Department are going to continue to advance, making these systems safer and more robust.



THE BELLS & WHISTLES OF RF COLLISION CONTROL

The large circle in the center of the photo shows the collision-avoidance system display reading. The example here shows a collision impending directly from the right, as indicated by the yellow light. Simultaneously, voice commands from the device will alert the driver of the direction of the impending collision, in this case saying “collision alert at 3 o'clock.”

The rest of the display follows, from left to right:

STATUS INDICATOR

If the system has successfully preempted the traffic signal so that the on-coming emergency vehicle is guaranteed a green light, the status light will show green. If not, the status light will show red.

MODE THREE-POSITION TOGGLE SWITCH

This feature has L.E.D.’s that provide visual confirmation of mode setting to the right of the switch:
  • Auto
    Preemption is automatically engaged and disengaged based on light bar and transmission/parking brake status. Even when the siren and light bar are not activated, the audio and visual collision avoidance features remain operative.
  • Manual
    LED lights green when the toggle switch is in manual mode. Traffic signal preemption is constantly engaged, and both audio and visual collision avoidance features are operational.
  • Off
    LED lights red when the toggle switch is in off mode. In this mode, traffic signals are not preempted. Visual and audible collision alarms still remain operative unless the audio alarm toggle is in the off position.


AUDIO ALARM TWO-POSITION TOGGLE SWITCH

This feature allows the operator to manually silence the intrusive audible collision alarm. This is particularly useful if the system is used in an ambulance and has a heart-attack patient on board. On and off positions of this switch are visually confirmed by a green or red LED to the left of the switch.

AUDIO ALARM VOLUME KNOB

This is a rheostat that allows the operator to adjust the volume of the intrusive audible collision alarm, and voice commands which announce preemption status and collision avoidance vectors, if any, to the user.