Effects of Yellow Rectangular Rapid-Flashing Beacons on Yielding at Multilane Uncontrolled Crosswalks
CHAPTER 8. SUMMARY, CONCLUSION, AND DISCUSSION
SUMMARY
The results of the first experiment showed that the RRFB produced an increase in yielding behavior at multilane uncontrolled crosswalk locations. In addition, installing additional beacons on the median island further improved the efficacy of the system.
The second experiment compared the RRFB with a traditional overhead yellow flashing beacon and a side-mounted traditional yellow flashing beacon. The results showed that the RRFB system was more effective at increasing driver yielding behavior than the traditional beacon system.
The third experiment showed that the RRFB was highly effective in increasing yielding behavior at a large number of sites located in three cities in the United States and that these effects were maintained over time at each location.
The fourth experiment showed that while the use of Direct Aim® lighting increased yielding compliance, further increases in yielding were not achieved by implementing MLB.
The fifth experiment showed that the use of RRFB devices, with the addition of advance warning devices placed before the crosswalk, did not increase yielding compliance but may have increased the distance that drivers yielded in advance of the crosswalk.
CONCLUSION
In conclusion, the study found the following:
The installation of the two-beacon system in experiment 1 increased yielding compliance from 18 to 81 percent, which was statistically significant. Yielding compliance increased from 81 to 88 percent following the installation of the four-beacon system at these sites, which was statistically significant. The percentage of drivers yielding at more than 100 ft doubled over the baseline condition during the four-system treatment. Many of the drivers yielded at distances much greater than 100 ft after the RRFB system was installed. This outcome reduced the chance that a pedestrian may have been struck by drivers due to the inability to see the pedestrian when a yielding vehicle blocked the view of the driver in the passing vehicle. The installation of a standard yellow overhead beacon increased yielding compliance from 11 to 16 percent. When side-mounted RRFBs replaced the overhead beacon, yielding compliance increased to 78 percent. Adding the RRFB to the median island increased yielding compliance to 88 percent. The installation of standard yellow side-mounted beacons increased yielding compliance from zero to 16 percent. The installation of side-mounted RRFBs increased yielding compliance to 72 percent. The increases produced by the RRFB system were statistically significant. The effects of the RRFB on driver yielding persisted for 2 years, and there was no tendency for them to decrease in effectiveness. These effects were statistically significant.
DISCUSSION
All comparisons of different systems or variations of the same system were conducted at the same sites, eliminating site characteristics as a confounding variable. Another strong point of this study was the large number of systems installed and evaluated.
The increased effectiveness of the four-beacon system over the two-beacon system may have been due to better visibility of the median island rapid-flash beacons for drivers occupying the inside lanes. This effect would be expected to be most pronounced when there were large vehicles in the outside lane that could block drivers' views.
Another important finding from this study was the increased percentage of drivers yielding well in advance of the crosswalk. The increases in yielding percentages and the yielding distances should be associated with a marked decrease in the number of vehicle passes or attempts to pass. This effect should be expected because of the signs' visibility to all drivers and not only those in the direct field of vision of the pedestrian.
One possible explanation of why the RRFB system produced a larger increase in driver yielding over the baseline is that it produced a novelty effect where an unfamiliar stimulus that had not been encountered by the drivers in the past was more likely to get their attention (similar to a unusual sound getting someone's attention). If this was the case, there should be a large decrease in yielding behavior over time; however, this was not found. The follow-up data (experiments 1
and 3) showed that the systems were still associated with high yielding behavior 1 and 2 years after installation. It appears that the lights on the system were such a salient stimulus that they obtained drivers' attention over the other competing stimuli and distractions they were exposed to when driving.
One problem that may arise is promoting the activation of the devices (i.e., pushing the devices' activation buttons). If a device is not activated, it is not effective. Some RRFBs contain sensors that detect pedestrians in the immediate area of the crosswalk and deliver an audible voice prompt that encourages pedestrians to activate the before crossing the street. No systematic data were collected to evaluate the efficacy of this feature.
The current device was not designed specifically for visually impaired pedestrians. It does not have a locator tone, but it does have a proximity sensor that provides an audible message when a pedestrian is in proximity to the device. When the button is pressed, another audible message confirms the button press and asks the pedestrian to wait for cars to stop before crossing. No other accessibility feature is included. Research should determine whether marked crosswalks
at uncontrolled locations fitted with an RRFB are suitable or can be made suitable for use by visually impaired pedestrians.
These results show that the rectangular LED yellow rapid-flashing beacon appeared to be an effective tool for producing a large increase in the percentage of drivers yielding right-of-way to pedestrians in crosswalks at sites where drivers rarely yielded to pedestrians. Therefore, it
should be a valuable tool for improving the pedestrian level of service at marked uncontrolled crosswalks. When used in conjunction with advance yield marking, it may also greatly increase the safety at uncontrolled crosswalks at high ADT multilane sites. As more sites are installed, a crash study should be conducted to determine if RRFBs increase the safety of crossings at high ADT multilane sites.
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