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Study highlights best practices for emergency vehicle visibility, conspicuity


By Jamie Thompson
FireRescue1 Editor

A new study has highlighted best practices for emergency vehicle visibility and conspicuity but warned further research is "critically needed." 

The report by the USFA, in partnership with the International Fire Service Training Association, covers retroreflective striping and chevrons, high-visibility paint, built-in passive light, and other reflectors for fire apparatus, EMS vehicles and law enforcement patrol vehicles.

Its key findings are:

  • The increased use of retroreflective materials holds great promise for enhancing the conspicuity of emergency vehicles.
  • Both visibility and recognition are important facets of emergency vehicle conspicuity. 
  • The use of contrasting colors can assist drivers with locating a hazard amid the visual clutter of the roadway.
  • Fluorescent colors (especially fluorescent yellow-green and orange) offer higher visibility during daylight hours.
  • There is limited scientific evidence that drivers are "drawn into" highly-visible emergency vehicles.
  • It is theoretically possible to "over-do" the use of retroreflective materials and interfere with drivers' abilities to recognize other hazards.
  • Effectiveness of the "Battenburg" pattern in the UK appears primarily related to its association with police vehicles

The study concludes that a combination of both "active and passive" conspicuity treatments — such as enhanced emergency vehicle warning lighting systems and the increased use of retroreflective materials — will all help improve the visibility and recognizability (when desired) of emergency vehicles.

It adds that further research specific to emergency vehicle visibility and conspicuity is needed in the United States, with particular emphasis on the interaction between civilian drivers and emergency vehicles during responses and on incident scenes.

"With vehicle crashes and emergency responders being struck on the roadway being a major cause of on-duty fatalities, it is important to examine all technologies to reduce this tragic cause of death," said USFA Deputy Fire Administrator Glenn A. Gaines.

The study was supported by the U.S. Department of Justice - National Institute of Justice as part of efforts to enhance emergency vehicle and roadway operations safety for firefighters, law enforcement officers and other emergency responders.

Preliminary firefighter fatality statistics for last year show that 29 of 114 firefighters killed on duty died in motor vehicle crashes. In addition, more law enforcement officers have died in traffic-related incidents than from any other cause in the past 10 years, while aggregated data shows at least 67 EMS providers were killed in ground transportation-related events over a six-year period from 1992.

The study also highlights potential opportunities for improving the safety of emergency vehicles using readily available products:

  • Outline vehicle boundaries with "contour markings" using retroreflective material, especially on large vehicles.
  • Concentrate retroreflective material lower on emergency vehicles to optimize interaction with approaching vehicles' headlamps.
  • Consider (and allow) the use of fluorescent retroreflective materials in applications where a high degree of day-/night-time visibility is desired.
  • Using high-efficiency retroreflective material can improve conspicuity while reducing the amount of vehicle surface area requiring treatment.
  • Applying distinctive logos or emblems made with retroreflective material can improve emergency vehicle visibility and recognition.
  • For law enforcement vehicles, retroreflective material can be concentrated on the rear to maintain stealth when facing traffic or patrolling.

The latest revision to NFPA 1901 Standard for Motorized Fire Apparatus became effective in January, requiring retroreflective striping in multiple locations on new fire trucks.

"While the application of retroreflective striping and trim is nothing new for fire apparatus, the amount demanded by the 2009 edition of NFPA 1901 drew a great deal of comment from the United States fire service, particularly related to the chevrons used for marking rear-facing surfaces," the report said.

"The most controversial issue was the requirement for a standardized red and yellow/fluorescent yellow/fluorescent yellow-green pattern for the chevrons. Many commenters on the proposed 2009 edition of NFPA 1901 supported the notion of retroreflective chevrons, but felt strongly about selecting their own striping colors to match the rest of the vehicle's livery.

"The NFPA Technical Committee on Fire Department Apparatus ultimately decided that standardization across the United States was the best course of action."

Key findings
One of the key findings on retroreflective materials in the study was the apparent confirmation that properly applied and maintained retroreflective sheeting materials can effectively increase the nighttime visibility and conspicuity of treated objects.

"While generalizing practices (without rigorous evaluation) used in other disciplines and/or countries remains a concern, the current research suggests that leveraging the properties of readily available retroreflective sheeting products, by incorporating them into U.S. emergency vehicle designs, appears promising for enhancing emergency vehicle visibility and conspicuity, especially during dark lighting conditions," it said.

The study said there is limited scientific evidence to support the notion of the "moth effect" — that drivers steer toward bright lights such as those used to increase the visibility of emergency vehicles like “moths to a flame."

However, several recent studies suggest that while bright lights may not be the cause, drivers' fixation on roadside objects can cause their steering to drift in the direction of their gaze, according to the study.

"This effect may be more pronounced with other impairments," it said. "The implications of these findings on emergency vehicle visibility/conspicuity are unknown, but certainly support the need for additional research on how to design passive conspicuity treatments so they draw drivers’ attention enough to induce the appropriate ("stay away") response, without causing the potentially negative results of visual fixation," said the report.

The study was put together by a panel of experts spanning the emergency services and relevant manufacturers, and included Robert Tutterow, vice president of the Fire Industry Equipment Research Organization and health and safety officer at the Charlotte, N.C., Fire Department.

Tutterow, who also sits on the NFPA 1901 committee, said the study provides good baseline knowledge to enable further research, and confirms the importance of several key areas such as daytime visibility.

"I think firefighters tend to think that conspicuity is primarily a nighttime issue, but we know for a fact that isn't true," he said. "It's an issue for all lighting conditions and I think we see as many incidents in daylight as we do at night."

He said the importance of emergency vehicle visibility and conspicuity on roadways is more vital today than it ever has been. "Drivers in cars are more distracted nowadays with mobile phones, GPS and entertainment systems," Tutterow said. "They are focused on everything but driving, which really highlights the importance of this study."

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