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Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations
This magazine is an archived publication and may contain dated technical, contact, and link information.
|Publication Number: Date: January/February 2004|
Issue No: Vol. 67 No. 4
Date: January/February 2004
FHWA is testing in-pavement flashing warning lights at a pedestrian crossing in a Virginia community.
|This night photo shows a lighted crosswalk in a northern Virginia suburb.
All photographs: Ted Shafer
Just about every journey involves walking—to the car, to the bus stop, to shopping, around parking lots, across streets, on paths, or on the sides of roads. However, traveling on foot can be dangerous. According to crash statistics for 2001, a pedestrian in the United States was injured on average every 7 minutes, and one was killed every 108 minutes. The Federal Highway Administration (FHWA) has made improved pedestrian safety part of its “vital few” priorities and seeks to achieve a 10 percent reduction in pedestrian fatalities by 2007.
Research staff members from the FHWA Office of Safety Research and Development at the Turner-Fairbank Highway Research Center are investigating ways to help reach this safety goal. Among the research topics is the evaluation of countermeasures to improve safety in pedestrian crossings that are not controlled by traffic signals.
Transportation agencies are installing in-roadway warning lights (also known as “in-pavement lighting” or “flashing crosswalks”) around the United States in an effort to improve pedestrian safety. Each side of a crosswalk is lined with a series of amber lights embedded in the roadway that face oncoming traffic. The lights are visible to approaching drivers as a warning that a pedestrian is in the marked crosswalk or near it.
Lights are actuated in one of two ways. In one system, the pedestrian activates the lights by using a traditional push button. In another, the pedestrian is “sensed” by an automatic detection system that triggers the lights.
Past evaluations found that in-roadway warning lights increase driver yielding at crosswalks and that this effect may be greatest in overcast conditions. Some practitioners are concerned, however, that drivers will become accustomed to the lights over time and that the yield rates will decline.
|This closeup shot shows one of the warning lights in a crosswalk.|
Further, pedestrians may misunderstand the function of the lights. “[There] may be some confusion over the meaning of the lights,” says Bob Garbacz, division chief with the Department of Transportation and Environmental Services in Alexandria, VA. “Many pedestrians may assume that they have the right of way when the lights are flashing. This is not the case. The lights flash yellow, which is not a 'stop' condition. Flashing yellow means that vehicular traffic may proceed only with caution.
|A family crosses the road where the in-pavement lights will be installed in Alexandria, VA.|
The FHWA researchers selected a site in Alexandria to investigate pedestrian and driver behavior at crosswalks during daylight and dark conditions over the course of a year. Evaluations will be conducted immediately before, immediately after, and a year after in-roadway warning lights are installed.
Throwing Light on Illuminated Crosswalks
As early as 1978, researchers began investigating illuminated crosswalks, such as a specialized system that projected light onto the roadway across the length of the crosswalk as a warning sign. Examining almost 200 sites in Israel over a 1- to 2-year period, the researchers found a reduction in nighttime pedestrian incidents compared to sites serving as controls.
Not until the early 1990s did the concept of in-roadway lighting become a reality in the United States. Since then, several companies have been manufacturing in-roadway warning light systems. Recently, FHWA approved the application of in-roadway warning lights at marked crosswalks at intersections that are not controlled by traffic signals. The new guidance is available in the Manual on Uniform Traffic Control Devices, in Chapter 4L, In-Roadway Lights. (See http://mutcd.fhwa.dot.gov/HTM/2003/part4/part4l.htm.)
Seeing the Light
A review of research over the past decade indicates that the installation of in-roadway warning lights has immediate positive effects on driver behavior. According to the research, in-roadway warning lights improve drivers' awareness of crosswalks and pedestrians who are present in them. After the installation of the lights, motorist yield behavior increases; that is, more drivers stop or slow down when pedestrians attempt to cross the road than before the warning lights were present. Researchers, including P.D. Prevedouros, have observed that speed near crosswalks also declined after in-roadway warning lights were activated.
These positive effects make inroadway warning lights an appealing solution at difficult crossing locations. Researchers P. Boyce and J. Van Derlofske, however, have expressed concern that the meaning of the lights has been unclear to motorists and pedestrians alike. In one case, researchers observed that pedestrians, who could have used the lighted crosswalk, did not and instead crossed elsewhere on the road. Observations from this study also suggested that it was difficult for pedestrians to know whether the lights were on or not, and drivers did not know what to do when the lights were flashing. Some drivers slowed but continued across the intersection in front of a pedestrian, while others stopped and waited for the lights to stop flashing, even when no pedestrian was present.
Some question also exists as to how often and under what conditions pedestrians actually activate the lights when a push button is available. At one study site, Whitlock and Weinberger found that only 33 percent of crossing pedestrians activated the lights by pressing the button. Little is known about the conditions under which pedestrians choose to activate the lights and whether they result in inconsistencies that are confusing to drivers. This problem can be countered by an automatic infrared or microwave device for detecting waiting pedestrians. If automatic detection is used, a button should enable the pedestrian to override the system in case the automatic detection device fails.
Like Day and Night
Statistics from a report by the National Center for Statistics and Analysis indicate that pedestrians are unsafe in a variety of lighting conditions. In 2001, daylight, dark, and “dark but lighted” conditions each accounted for about a third of the total pedestrian fatalities.
Many people expect that in-roadway warning lights will be most effective under dark conditions, such as dusk or dawn, night, or inclement weather. One early research study by Whitlock and Weinberger reported that driver yield behavior was greatest in adverse conditions such as darkness or fog. At several sites, the installation of in-roadway warning lights led to larger increases in yield rates and greater braking distances between drivers and pedestrians at night. But this effect has not received further attention by researchers.
Most of the research on in-roadway warning lighting has ignored whether positive effects persist over time. Those studies that have examined the persistence of changes over time report mixed results. Whitlock and Weinberger noted that 2 years after installation, drivers at one site were observed making sweeping motions with their heads approaching a crosswalk with in-roadway warning lights, ostensibly scanning for pedestrians. Additionally, drivers' yielding and braking distances remained higher than the baseline observation.
Boyce and Van Derlofske found that adding in-roadway warning lights to a clearly striped location lead to a reduction in vehicle speed. This effect of lighting on speed tended to diminish over time. Thus, whether the effects of in-roadway warning lights are persistent is unclear at this time.
|A pedestrian crosses a lighted crosswalk at night.|
Answering the Question
To examine the effects of in-roadway lighting on pedestrian safety, the FHWA research team sought the assistance of transportation engineers in Alexandria, VA, to find locations where pedestrians experienced crossing difficulties and where in-roadway lights were planned. Results from a recent National Center for Statistics and Analysis report analyzing 2001 pedestrian fatalities nationwide indicate that (1) 64 percent occurred on urban roadways, (2) 40 percent occurred in areas with a posted speed limit below 64 kilometers per hour (40 miles per hour), and (3) 78 percent occurred at nonintersection locations. The FHWA team therefore sought a midblock crossing with a sizable pedestrian presence during the day and at night in a moderately urban neighborhood where the speed limit was less than 40 mph.
The selected crosswalk is on a four-lane divided road at a subway station. Garbacz says of the crosswalk, “The flashing beacons will improve pedestrian safety by alerting motorists that there may be pedestrians crossing the street. Multilane crossings are particularly dangerous for pedestrians because large vehicles [may] block the view of the pedestrian from other motorists.”
Installation of lights using push button actuation will occur in early 2004. The study is structured so that data will be collected immediately before and after the installation of the lights and again a year later. The FHWA researchers will address the following questions:
Investigating the impact of inroadway warning lights serves the goals of FHWA's “vital few” strategic initiatives. First, the results will add to an understanding of successful countermeasures for pedestrian safety. Second, the study will create the necessary knowledge to guide installation recommendations and justifications. This guidance will assist practitioners in making informed decisions that protect road users in a cost-effective manner.
For more information on bridge research at FHWA, visit www.tfhrc.gov/structur/.
Sheryl Miller received a B.A. in psychology from the State University of New York at Geneseo in 1995 and an M.A. in psychology from George Mason University, Fairfax, VA, in 1997. She expects to receive her Ph.D. from George Mason University in 2003, specializing in human factors and applied cognitive psychology. Miller is employed by Science Applications International Corporation and works at Turner-Fairbank Highway Research Center (TFHRC) on the Human Centered Systems team, specializing in pedestrian and bicycle safety research.
Gabriel K. Rousseau is an engineering research psychologist in FHWA's Office of Safety Research and Development at TFHRC. He leads the Human Centered Systems team's research on speed management and pedestrian and bicyclist safety. He received a Ph.D. in cognitive/experimental psychology from the University of Georgia and completed a postdoctoral fellowship at Georgia Institute of Technology.
Ann H. Do received a B.S. in civil engineering from Virginia Polytechnic Institute and State University, Blacksburg, VA, in 1987. She joined FHWA in 1990 as a highway design engineer. She currently serves as research highway engineer for TFHRC. Do has been the program manager for the FHWA pedestrian and bicycle safety research since 2001. She works in the Office of Safety Research and Development, specializing in research related to safety effectiveness evaluations, pedestrians, bicycles, human factors engineering, and geometric design.
For more information, see http://www.fhwa.dot.gov/research/topics/safety/pedbike/ or contact Ann Do at 202-493-3319 or email@example.com. For references, see the online version of PUBLIC ROADS.