It is essential that every effort be made to quickly clear an incident scene, while also protecting the lives of both responders and the traveling public.
Another important factor to consider is the visibility of emergency vehicles. Vehicle lights and reflective stripes allow emergency vehicles to be seen through both active and passive visual warnings. The key is to use them effectively.
As stated in the U. S. Fire Administration’s 2008 report, Traffic Incident Management Systems, “While it is clear that some lighting is necessary in order to warn approaching motorists of the presence of emergency responders, it is also suspected that too much or certain types of lighting can actually increase the hazard to personnel operating on the scene, particularly during nighttime operations.” (1)
Light Discipline
Responders must understand the importance of light discipline. Just because responders have many lights available, doesn’t mean they have to use all of them. Responders should be aware of the following:
Emergency vehicle headlights should be deployed in a manner that is not blinding to motorists. Headlights shining directly into oncoming traffic can result in drivers passing the incident scene in a temporarily blinded condition. It takes drivers from 3 to 6 seconds to recover from the effects of glare. (1) At 65 miles per hours, vehicles travel over 95 feet per second and in just 3 seconds at that speed, a driver will travel almost the length of a football field in a temporarily blinded condition. This puts everyone at risk, including emergency responders.
On-scene responders may be in a position to see oncoming traffic well, but that does not mean that oncoming drivers can see responders well. If emergency vehicle headlights are shining directly at oncoming traffic, drivers may not be able to see responders at all.
Emergency warning lights should be minimized as conditions warrant. There comes a point where more is not better. Evidence suggests that strong stimuli – such as the combination of lights and flashes – attract central gaze, which can cause drivers to steer in the direction of that gaze. This has been termed the “moth effect” and could have dangerous consequences for on-scene responders. It generally is believed that this visual attraction is further accentuated when the driver is under the influence of drugs and alcohol. (1) As stated in the Texas Manual on Uniform Traffic Control Devices, “The use of emergency-vehicle lighting can be reduced if good traffic control has been established at a traffic incident scene. This is especially true for major traffic incidents that might involve a number of emergency vehicles.” (2)
Retroreflective Strips
Retroreflective stripes enhance the visibility of emergency response vehicles and work by reflecting light from the headlights of approaching vehicles back to the driver. Whereas lights provide an active visual warning (require electric power), retroreflective stripes provide a passive visual warning (no need for power).
Several years ago, the Texas Department of Transportation (TXDOT) implemented a chevron pattern of retroreflective stripes on the back of its work vehicles. Why? To increase the visibility of these vehicles at a greater distance and lessen the chance of rear-end crashes.
In 2008, the National Fire Protection Association (NFPA) adopted revised standard NFPA 1901 calling for the use of a chevron pattern of retroreflective striping on the rear of automotive fire apparatus. (3) This standard calls for the following:
· At least 50 percent of the rear-facing vertical surfaces, visible from the rear of the apparatus, excluding any pump panel areas not covered by a door, shall be equipped with retroreflective striping in a chevron pattern sloping downward and away from the centerline of the vehicle at an angle of 45 degrees.
· Each stripe in the chevron shall be a single color alternating between red and either yellow, fluorescent yellow or fluorescent yellow-green.
· Each stripe shall be 6 inches (150 mm) in width.
When it comes to lights at the scene of an accident, remember, more is not always better. Keep the passing motorists in mind – it may save your life.
References:
(1) Traffic Incident Management Systems, April, 2008, U. S. Fire Administration, Federal Emergency Management Agency (FEMA), prepared with the cooperation of the Federal Highway Administration.
(2) Section 6I.05, Use of Emergency-Vehicle Lighting, Texas Manual on Uniform Traffic Control Devices, 2006.
(3) NFPA 1901 Standard for Automotive Fire Apparatus, 2009 edition (effective date July 18, 2008).
About the Authors: Howard McCann, PE, is the Texas Engineering Extension Service’s Transportation Training director. Robert Averitt is a TEEX adjunct instructor and is a 28-year veteran of the Austin Police Department. Elmer Williams is a TEEX adjunct instructor, a certified peace officer and an 18-year veteran of the Houston Fire Department.
About the Texas Engineering Extension Service
The Texas Engineering Extension Service (TEEX) is a member of the Texas A&M University System and offers hands-on, customized first-responder training, homeland security exercises, technical assistance and technology transfer services impacting Texas and beyond. TEEX programs include fire services, homeland security, law enforcement, public works, safety and health, search and rescue, and economic development.