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Do More Emergency Lights Make You Safer?

Written by Mark Karczewski and John Swain

Improving emergency responder safety at emergency scenes is an ongoing process that continues to engage the attention and energy of many different people. A wide variety of factors affect the safety of emergency responders. This article reports the results of an experiment exposing members of the public to two levels of emergency lighting on a rural interstate in the nighttime to observe the distances at which they first perceived the emergency lighting and to find out their impressions of emergency lighting in regard to distractedness.

An initial impulse of emergency responders at emergency sites is to use the maximum amount of emergency lighting under the assumption that more lighting is better. This impulse has two drawbacks. First, and less important, is that lights do not stop vehicles from running into emergency responders or their vehicles. Lights have no stopping power. Second, and greater in importance, is that lighting can distract drivers and cause rather than prevent emergency scene crashes.

People drive where they look. Bright lights draw people’s attention and may cause drivers to drive toward and into emergency vehicles.

Two important objectives of emergency lighting are to communicate that an emergency situation exists so as to warn vehicle operators of the need to exercise caution and to avoid distracting vehicle operators excessively or needlessly from the important task of driving safely.

First, emergency lighting should signal to drivers that an emergency situation exists at a sufficient distance so that drivers can react appropriately, e.g., gather, process, and act on information by slowing down and steering appropriately. Second, emergency lighting should not unduly distract drivers from their driving responsibilities. Unfortunately, emergency lighting that helps one objective may hurt another.

The purpose of this study was to determine the different effects of two levels of emergency lighting in regard to the distances at which they are perceived at night and their distractedness. The study used the lowest and highest levels of the emergency lighting displayed on a fully marked Illinois State Police patrol vehicle.

The test was conducted during the nighttime along Interstate 80 in a rural area of northern Illinois where the axis of travel is predominately east and west. The test was conducted in August 2003. The test did not include periods when rain or other visual impediments were present.

The test consisted of each subject viewing two levels of emergency lighting on an Illinois State Police car. The two levels used are the lowest and highest levels of emergency lighting available from a roof-mounted Code 3 MX 7000, the most commonly used lightbar on an Illinois State Police car.

The upper level has two low-speed rotating red lights on the left (100 flashes a minute), a high-speed rotating white light in the center (200 flashes per minute), and two low-speed rotating blue lights on the right (100 flashes per minute). The lower level has flashing lights with a rate of 120 flashes per minute. It has one flashing red light on the left, an arrow stick consisting of six flashing amber lights in the center, and a flashing blue light on the right. 

The highest level of lighting involved using all of the lights on both levels of the lightbar.  The lowest level of lighting involved using all of the lights on the lower level. In both cases, the arrow stick portion of the lightbar had the three arrow stick lights on the left and the three on the right alternatively on and off, i.e., the three on the left on and the three on the right off and then the opposite. During the test, the display vehicle did not show any other lights. Hereafter these two levels of emergency lighting display are referred to in terms of “higher” and “lower” levels.

The tester, the driver of the moving vehicle, asked people at the truck stop if they would volunteer to participate in the study, instructed the test participants about their roles, told the operator of the display vehicle when to turn on the emergency lighting display, and gathered information from test participants on the highway and later at the truck stop.

The tester asked persons chosen randomly at the truck stop if they were willing to participate voluntarily in a study observing emergency lighting that took about 20 minutes to complete. The tester instructed volunteers that they would indicate when they first saw emergency lighting and that they were encouraged to provide their impressions or opinions as to whether the lighting configurations they saw were distracting. The 26 volunteers appeared to be a reasonably representative cross section of motorists. The average age was approximately 39 years of age with a range from 25 to 56; nine were female and 17 were male.

One Illinois State Police patrol vehicle, with a Code 3 MX 7000 lightbar, was used to display rear-facing emergency lighting to subjects. The display vehicle was parked at a fixed location in the median of I-80. The test participants rode in the front passenger seat of another Illinois State Police patrol vehicle driven by a uniformed Illinois State Patrol Officer. The moving vehicle started at a truck stop near an entrance to I-80, which was about two miles from the display vehicle. The moving vehicle, which had a certified speedometer, entered I-80 and accelerated to a fixed speed of 60 miles per hour.

Volunteers were exposed to the two levels of emergency light in separate observations.  For the first observation, the tester driving the moving vehicle entered I-80, indicated to the operator of the display vehicle to turn on emergency lighting, accelerated to 60 mph, and started a stopwatch when the moving vehicle passed a fixed starting point. 

The fixed starting point was an exact distance from the display vehicle which made it possible to compute the distance between where test participants indicated they first saw emergency lighting from the display vehicle. When participants indicated that emergency lighting was visible to them, the stopwatch was stopped to note the lapsed time from the fixed starting point. For the second observations, the tester followed a similar process. 

After the first observation, the tester drove the moving vehicle down the highway in the same direction approximately 3.5 miles where he used a median crossover to stop to note the first elapsed time recorded on the stopwatch and comments about the emergency lighting display, to reset the stopwatch, to reverse direction, and to drive in the opposite direction (back toward the truck stop). 

Meantime, the operator of the display vehicle turned off the first emergency light display after the moving car passed, turned the car around so that the observer would see the emergency lighting from the rear, and turned on the other level of emergency lighting display when told to do so. When the tester drove the moving vehicle past another fixed point, the stopwatch was started for a second time and stopped when the participant indicated that emergency lighting had been observed. 

After the second observation, only a few participants were asked about the distractedness of the two emergency lighting displays. Meanwhile, the operator of the display car turned off the lighting display when the moving vehicle passed and turned the car around to display rear-facing lighting for the next observation. The order of the presentation of the two levels of emergency lighting were rotated so that each of the displays were seen the same number of times as the first and the second observation. A total of 26 sets of observations were made.

The test results are divided into the objective measurement of the distance at which the participants saw the two levels of emergency lighting displayed and subjective comments about the two emergency lighting displays. Each set of test results emphasizes one of the pair of concerns that we see with emergency lighting: concern for the distance at which the emergency lighting is visible and concern for driver distraction.

The average distance at which the test participants reported seeing the two levels of emergency lighting is 5,202 feet for the higher level and 4,312 feet for the lower level.  The average difference of the distances of perceptions of the two emergency lighting displays is approximately 900 feet. The greater amount and variety of lighting is associated with a greater visibility of an emergency vehicle. Drivers observing the higher level of emergency light have 900 more feet to respond to emergency vehicles at the scene of an emergency than those observing the lower level.

The difference between the two levels of lighting displays in the test in respect to distance can be viewed in several ways. First, the obvious advantage in seeing and being seen an average distance of 900 feet farther may lead some to conclude that the extra distance provides a greater margin of safety for emergency responders and the motoring public.  At a speed of 60 to 65 mph, drivers would have approximately nine to 10 seconds more to react to emergency lighting. 

Second, the apparent obvious advantage in distance of the higher level of lighting display may diminish in importance, when one realizes that even the person with the least acute vision in the study saw the lower level of emergency lighting at a distance of 3,256 feet, which was a distance that would allow a driver going 60-65 mph over 30 seconds to slow down and otherwise react in approaching an emergency scene. Although having an additional nine to 10 seconds to react to emergency lighting has some marginal value, that difference is not as important as it might first appear. 

Third, interestingly, the difference between the two levels of lighting is comparable to the differences in distance in respect to the perception of the white and amber colored lights in an earlier nighttime study focusing solely on the different colors of emergency lighting. In that study, the color and the average distances were white at 5,069 feet, amber at 4,153 feet, red at 3,710 feet, and blue at 3,136 feet.  

In this study and that study, the average difference in distance between perceptions of lighting displays using white lights and amber lights was approximately 900 feet. This coincidence of results between the two studies suggests that the color of emergency lighting is a matter to investigate further. 

Our conclusion on distance of perception is that for ordinary drivers the lower level of emergency lighting on an Illinois State Police car is adequate at nighttime under clear conditions for motorists to react appropriately to approaching stationary emergency scenes.

The comments that participants gave to the tester concerning the two levels of emergency lighting were recorded as either positive, negative or ambivalent. Also recorded were comments that suggested whether one level of lighting was more distracting than the other.

Most of the comments about the higher level of lighting were either negative (69%) or ambivalent (27%), while most of the comments about the lower level of lighting were either positive (62%) or ambivalent (23%). Whether one looks simply at the individual comments or the summary of the comments, the verbal reactions of the participants to the two levels of emergency lighting were strikingly different. 

The negative words that were used for the higher level of emergency lighting were not ones that emergency responders would prefer to have as descriptors of how drivers approaching a scene where they are dealing with an emergency are reacting to their lighting: “frightening, overpowering, very disturbing, distracting, confused me, too much, can only see spots, worse as you get closer, left me seeing spots, and had to concentrate.”

Conversely, few participants gave negative reactions to the lower level of emergency lighting. The negative comments were 69% for the higher level and 15% for the lower level. 

Our interpretations of the comments suggest that 77% of the participants found the higher level of lighting more distracting than the lower level. In some cases, the words used stated or suggested driver distraction, usually when viewing the higher level of lighting display. In several cases, the words used suggest vision difficulties or confusion on the part of drivers. One driver indicated that the higher level of lighting was “worse as you get closer.” Drivers with vision difficulties closer to emergency lighting are also closer to emergency responders.

The comments on specific colors are interesting. “White stands out,” and “White washed out the other colors.” The same two participants indicated, “Amber was easier to tolerate,” and “Could only see amber.” Another participant said, “Amber was all I saw.”

In these comments, as well as the distances of perception in the earlier study, both white and amber appear to be more dominant than the two other emergency lighting colors in the vision of observers. Red and blue may not serve to warn people driving toward emergency scenes as much as might have been previously presumed.

The results of this experiment at nighttime indicate that a higher level of emergency lighting provides visibility at a greater distance but also more distraction. Also, it appears that the color of emergency lighting makes a difference. Our conclusion is that more lighting in the nighttime at an emergency scene does not make you safer. 

Our judgment is that the negative side of a higher level of emergency lighting outweighs the positive side. The negative side is that drivers appear to be much more likely to be distracted by higher levels of emergency lighting. The positive side is being visible at a greater distance affords drivers more time to react appropriately. The greater visibility appears to be less important in our opinion than reducing the increased chance of being hit by distracted drivers.

 

Mark Karczewski is a master sergeant and 13 year veteran with the Illinois State Police and a specialist in traffic incident management programs. He may be reached at mark-karczewski@isp.state.il.us. John W. Swain is the Director of the Institute for Public Policy and Administration at Governors State University in University Park, Illinois. He may be reached at j-swain@govst.edu.


Published in Law and Order, Mar 2004

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