Encouraging Best Behavior
The results are in from recent FHWA research: Pedestrian hybrid beacons continue to improve safety at unsignalized crossings.
Since their development in the late 1990s, pedestrian hybrid beacons (PHBs) are seeing increased use. This street crossing treatment, which consists of pedestrian signal faces for those pedestrians entering a marked crosswalk and beacon faces for drivers of vehicles who are about to pass through the crosswalk, is successful in reducing the number of pedestrian-vehicle conflicts.
Compared to conventional midblock pedestrian signals, PHBs allow greater vehicular throughput on major streets, especially at sites with long crosswalks, because drivers have the option of proceeding after stopping during the pedestrian’s flashing Don’t Walk interval if they can do so without conflicting with pedestrians. Furthermore, as noted in a 2010 study released by the Federal Highway Administration, Safety Effectiveness of the HAWK Pedestrian Crossing Treatment (FHWA-HRT-10-042), the “PHB can provide greater safety than the other pedestrian crossing options for crossing busy arterials without the drawbacks of a traditional signal. Whereas [previous research shows] traditional signals may increase crashes, especially rear-end crashes, the PHB has been found to reduce the potential for pedestrian crashes by 69 percent and total crashes by 29 percent for great overall safety.”
Despite such success, some transportation engineers remain reluctant to implement PHBs and continue to ask questions about the performance of the treatment. For example, when the PHB rests in a dark (unlighted) indication, do some drivers mistake it for a malfunctioning signal and stop needlessly? How do drivers on minor approaches (cross streets or driveways near the crossing) behave when the PHB sequence is active? How well do drivers and pedestrians comply with the control that the PHB provides for them, and do pedestrians consistently push the button before crossing?
In 2016, FHWA published the results of a followup research project, Evaluation of Pedestrian Hybrid Beacon and Rapid Flashing Beacons (FHWA-HRT-16-040) to answer such questions by recording driver and pedestrian behaviors at existing sites.
Monique Evans, director of the Office of Safety Research and Development with FHWA, says, “As long as pedestrians are involved in fatality and injury crashes, identifying and promoting treatments that improve pedestrian safety and mobility will be an important part of what we do…. We want to encourage agencies to adopt practices and use tools that make it easier and safer for pedestrians to travel from place to place.”
Answering engineers’ questions by providing evidence of the efficacy of PHBs could go a long way toward promoting their use.
What Are PHBs?
PHBs are thought to offer increased safety in uncontrolled, marked crosswalks by raising motorist awareness of the presence of pedestrians at those locations and by displaying red signal indications (either steady or flashing) that legally require drivers to stop.
PHBs differ from traditional midblock pedestrian signals and constantly flashing warnings in that the PHB indications remain in an unlighted state for drivers until activated by a passive pedestrian detector or a pedestrian button press. When activated, the PHB sequence for drivers begins with a flashing yellow indication followed by a steady yellow indication to alert them to the upcoming need to stop for pedestrians. Then the PHB presents a dual steady red indication for drivers and a Walk indication for pedestrians, followed by alternating flashing red indications for drivers while pedestrians see their flashing Don’t Walk indication and on most installations a countdown indication. This sequence requires drivers to stop and remain stopped while pedestrians cross, but allows drivers to proceed with caution after stopping if they can do so without conflicting with pedestrians.
Communities can use the PHB at several types of locations, including midblock marked locations where pedestrians need assistance across a major street, or crossings near minor approaches such as cross streets or driveways. On major streets that have medians wide enough to serve as a pedestrian refuge area, communities have used PHBs to enable two-staged crossings where each side of the road is controlled independently.
The Early Years
Richard B. Nassi, P.E., Ph.D., a retired transportation administrator for Tucson, AZ, developed the first PHB, then known as a High-intensity Activated crossWalK (or HAWK), after returning from a trip to England where a similar beacon was in use. Nassi noted, “The PHB (HAWK) was chosen over the traditional [traffic control] signal because a signal at a crossing at a residential street frequently will attract unwanted traffic and speeds to the residential street, turning it into a de facto [minor] arterial street and creating neighborhood traffic mitigation problems.” The increase in traffic and speeds occurs because a signal can create a gap in the major traffic stream, encouraging more “cut through” traffic on the residential street. This traffic can be associated with higher speeds.
In the late 1990s, the city of Tucson started using PHBs, and since then at least 42 States plus the District of Columbia and the Indian nations in Arizona have joined in.
In 2009, the PHB was added to part 4 of the Manual on Uniform Traffic Control Devices (MUTCD). The MUTCD allows the PHB to be installed at a marked crosswalk where a traffic signal is not warranted, or a signal could be warranted but a decision has been made not to install it. Warrants in the MUTCD chapter 4F assist in determining whether a PHB would be potentially beneficial based on vehicle and pedestrian volumes, vehicle speeds, and crosswalk length (see paragraphs 5 through 8 of section 4F.01). Additional guidelines address questions about signing, pavement marking, and timing the durations of the vehicular and pedestrian indications.
Since 2010, the city of Austin, TX, has installed 45 PHBs. Gary Schatz, former city transportation engineer, reports that “the decision to install PHBs was based on the fact that the community was frustrated with the apparent lack of effectiveness of flashing warning beacons and marked crosswalks alone. By implementing PHBs, the city of Austin was better able to meet community expectations [for a majority of motorists to stop in advance of the crosswalks]. We received numerous letters of thanks and appreciation for installing PHBs.”
Similarly, Nassi reports that the city of Tucson has more than 100 installations and, to date, has not had a fatal crash at any of the PHB crossings.
In spite of these positive results, engineers’ remaining questions led FHWA to conduct an open-road study with the objective of examining actual driver and pedestrian behaviors at crosswalks with PHBs.
Selection of Study Sites
The FHWA research team for the Evaluation of Pedestrian Hybrid Beacons and Rapid Flashing Beacons study, which covers October 2012–March 2016, identified a total of 20 study sites in Austin, TX, and Tucson, AZ, two cities that have used the PHB extensively. The study sites collectively represented a range of key characteristics, such as traffic volume, speed limit, number of lanes, and median width and type.
Some sites are located at stop-controlled intersections, others near driveways, and others at midblock locations where pedestrians cross. The sites are in a variety of areas, including suburban residential neighborhoods, school campuses, and in sites near small and large businesses.
Data Collection And Reduction
From the selected sites, the research team collected nearly 80 hours of video footage, observing approximately 1,100 PHB activations and nearly 2,000 pedestrian crossings at PHB-controlled crosswalks. Approximately 1,700 of the observed pedestrians were members of the public (nonstaged pedestrians), and about 300 were members of the research team conducting staged crossings. The researchers then reduced the data by reviewing the video footage to obtain insights into driver and pedestrian behaviors, as well as the prevalence of pedestrian-vehicle conflicts.
Overall, about 96 percent of drivers yielded to pedestrians in the crosswalk when the PHB was active at the studied sites. A small number of violations occurred where drivers either ran the steady or flashing red indications or proceeded during flashing red when pedestrians were still present in the crosswalk. Most of these violations occurred either a short time after the start of the steady red indication or immediately after pedestrians had cleared the driver’s lane.
Researchers observed no drivers stopping solely because the dark PHB was present. They did observe a small number of stops in the presence of a dark PHB because of congestion on the street or because a pedestrian was using the crosswalk without first activating the PHBs but none while traffic was flowing freely and the crosswalk was clear.
Researchers closely observed the behavior of minor-movement drivers--those traveling on or turning onto the minor crossroad at an intersection--while PHBs were active. This effort included drivers who did not have to pass through the beacon-controlled crosswalk but were still required to stop because of STOP signs (drivers on cross streets or driveways) or the PHBs’ red indications (drivers making a left turn from the major street). The analysis revealed that minor-movement drivers would often use gaps that were created in the major-street traffic while the PHB was active, taking advantage of the opportunity to complete their maneuver.
Stop compliance was generally high among minor-movement drivers, although violation rates were notably high (five violations per hour or more) for movements at seven of the sites. These movements were for drivers entering or exiting major traffic generators such as school campuses or well-patronized supermarkets. The observed violations did not involve any interaction with pedestrians in the PHB-controlled crosswalks.
The 1,700 nonstaged pedestrians were generally compliant with the PHB indications. About 80 percent began their crossing movements while the steady or flashing red indications were provided to drivers. Only about 7 percent of the nonstaged pedestrians started crossing while the PHB was dark, and these crossings typically occurred during periods of low vehicular volume when it was easy for pedestrians to cross.
Pedestrian compliance was higher at sites that had higher vehicular volumes. Specifically, only 20 percent of all observed noncompliant crossings occurred when vehicular volumes exceeded 6 vehicles per minute per lane, and less than 5 percent occurred when vehicular volumes exceeded 10 vehicles per minute per lane.
The research team observed the nonstaged pedestrians to determine how often they pushed the button before crossing at the beacon-controlled crosswalk. This analysis revealed that more than 90 percent of pedestrians who could have pushed the button (because they intended to cross and other pedestrians had not yet pushed the button) did so. Pushbutton usage was especially common at sites with vehicle volumes in excess of 2,000 vehicles per hour. At these sites, less than 5 percent of pedestrians chose not to push the button if they arrived while the PHB was inactive. In addition, more than 80 percent of pedestrians who pushed the button waited for their Walk indication before beginning to cross.
Of the 20 PHB data collection sites, 18 operated in “hot-button” mode where the PHB became active immediately when a pedestrian pushed a button. The other two sites were coordinated with adjacent traffic signals such that they would provide pedestrian service when platooned vehicles were not present on the major street.
Pedestrian behavior differed at the two coordinated sites in that a larger percentage of pedestrians started crossing while the PHB was inactive. At hot-button sites, about 6 percent of pedestrians started crossing during the dark indication, while about 13 percent of pedestrians did so at the coordinated sites. Departures on the dark indication were less common at the coordinated site that had pushbuttons next to red pilot lights that would illuminate when the button was pressed.
The research team reviewed the video footage to determine the rate of pedestrian-vehicle conflicts. A conflict was considered to occur when the driver or the pedestrian could be seen making a sudden change in their path or speed, suggesting that they perceived the potential for a crash. The researchers observed a total of 54 conflicts in the video footage, 38 involving through vehicles and 16 involving turning vehicles.
One key predictor of conflict rate is pedestrian compliance; pedestrians who started crossing against a steady or flashing Don’t Walk indication were about 58 percent more likely to experience a conflict with a vehicle. A notable number of these conflicts occurred at one of the sites that was operated in coordinated mode. The pedestrian pushbuttons at this site lacked audible or visual indicators that the button press had been registered, so it is likely that some pedestrians believed that the PHB was malfunctioning and decided not to wait for the start of the PHB sequence.
Many of the conflicts that involved turning vehicles occurred at a particular site that had high volumes of both pedestrians and vehicles, where the crosswalk was near a bus stop, or about 45 feet (14 meters) from a driveway serving a well-patronized supermarket. Drivers making left turns out of the driveway had little space to complete their turning movement before encountering the occupied crosswalk, and would sometimes encroach on pedestrians while trying to maneuver out of their diagonally oriented position. No conflicts were observed at a similar site that also had busy bus stops and a well-patronized supermarket, but with the distinction that the crosswalk was about 60 feet (18 meters) away from the driveway.
This study of operations and behavior of both drivers and pedestrians differs from previous FHWA studies of the PHB, which focused on safety (Safety Effectiveness of the HAWK Pedestrian Crossing Treatment). In the nearly 80 hours of video footage, very few drivers stopped when they encountered a PHB in a dark, inactive mode, and these drivers stopped either because of congestion on the street or because a pedestrian was crossing while the device was inactive. No drivers stopped because they mistook a dark PHB to be a malfunctioning traffic signal.
Driver yielding rates were high (about 96 percent) across the 20 PHB-controlled sites. Pedestrian compliance was also high, as about 70 percent of the observed pedestrians started crossing during the drivers’ steady red indication (when the pedestrians had a Walk indication), and more than 90 percent of pedestrians pushed the button when they intended to cross and the PHB was inactive. High compliance on the part of both drivers and pedestrians show that the PHB has significant potential to improve pedestrian safety at unsignalized crossing locations.
The MUTCD recommends that PHBs be coordinated with adjacent traffic signals if installed within a signal system, and 2 of the 20 PHB sites in this study were coordinated. Pedestrian departures on the dark indication were more common at the coordinated sites, although compliance was better at the coordinated site that had pushbuttons with red pilot lights to indicate PHB activation, compared with the coordinated site that did not have visual or audible confirmation of the button press.
Pedestrian-vehicle conflicts occurred more frequently with through vehicles than turning vehicles, particularly when the pedestrian was noncompliant. Some conflicts that involved turning vehicles occurred when drivers were making left turns out of a driveway that served a major traffic generator and the distance between the driveway and the crosswalk was not sufficient to allow the driver to complete the left-turning movement before encountering the crosswalk.
By incorporating the PHB in the 2009 MUTCD, FHWA made this pedestrian safety device available to practitioners to use at uncontrolled marked crosswalks to enhance pedestrian safety. FHWA plans to encourage more frequent implementation of PHBs at locations where they can be beneficial by proposing the elimination of the current recommendation that PHBs be located at least 100 feet (30 meters) from side streets or driveways that are controlled by STOP or YIELD signs. FHWA is also encouraging use of PHBs as one of the pedestrian safety countermeasures in an innovation called Safe Transportation for Every Pedestrian (STEP) being promoted under the fourth round of Every Day Counts (www.fhwa.dot.gov/innovation/everydaycounts).
Kay Fitzpatrick is a senior research engineer with the Texas A&M Transportation Institute. Her research areas include pedestrians, geometric design, and roadway safety. She has a B.S. and M.S. in civil engineering from Texas A&M University and a Ph.D. from Penn State.
Ann Do is a highway research engineer at FHWA’s Turner-Fairbank Highway Research Center in McLean, VA, where she has managed the Pedestrian and Bicycle Safety Research Program since 2001. She joined FHWA in 1990 as a highway design engineer with the Eastern Federal Lands Highway Division. Do specializes in research related to safety effectiveness evaluations, pedestrians, bicyclists, human factors engineering, and geometric design. She has a B.S. in civil engineering from Virginia Tech.
Michael P. Pratt is an assistant research engineer with the Texas A&M Transportation Institute. He has 11 years of experience in research on traffic operations and safety, geometric design, traffic control devices, and pedestrian safety. He holds a B.S. in civil engineering from UCLA and a master’s degree in civil engineering from Texas A&M University.
Bruce Friedman is a transportation specialist on FHWA’s MUTCD Team where his specific responsibilities include parts 4 and 8, Highway Traffic Signals and Traffic Control for Railroad and Light Rail Transit Grade Crossings, respectively. Friedman was a technical member of the National Committee on Uniform Traffic Control Devices (NCUTCD) for more than 25 years, and served as chair of the Signals Technical Committee and chair of the Institute of Transportation Engineers’ delegation to the NCUTCD. He has bachelor’s and master’s degrees in civil engineering from Georgia Tech.
For more information, contact Kay Fitzpatrick at 979–845–7321 or firstname.lastname@example.org, or Ann Do at 202–493–3319 or email@example.com.