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Abstract
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Countdown pedestrian signals (CPS) have been shown to be more intuitive than other crossing signals when communicating the amount of available crossing time at an intersection.
Survey research shows that the traditional flashing DON'T WALK (FDW) signal (i.e., the flashing hand) is poorly understood.(1,2) In contrast, comprehension for CPS tends to be much higher. Between 86 percent(3) and 100 percent of pedestrians understand CPS correctly.(2)
Field research indicates that the traditional FDW signal increases the likelihood of pedestrians initiating a crossing, running out of time while crossing, returning to the starting side of the crossing while crossing, or even stopping in the roadway once the light changes.(4)
Crash data suggest that when countdown timers are added to existing pedestrian signals, crashes decrease by 25 percent.(5) One field study illustrates that pedestrians are more likely to judge whether they have enough time to cross when only the CPS is used.(6) However, little information is available on how well pedestrians calculate the amount of time needed to cross.
The pedestrian change (or clearance) interval is designed to allow pedestrians enough time to finish crossing, after they have initiated a crossing, before the light changes. Before the use of countdown timers, the FDW displayed during the pedestrian change interval, signaled pedestrians to not start crossing and there was no way to tell if there was enough time to finish crossing. It was fine to finish crossing, however, if the pedestrian had started to cross before the FDW appeared.
Since pedestrians cross at different speeds, the timing of the FDW needed to be set at a value that would allow slower pedestrians to safely cross. At the time of this research, the trend toward calculating crossing times based on slower pedestrians meant that faster pedestrians, who arrived at the intersection during the FDW and could have easily crossed before the phase ended, were left trapped on the sidewalk. The addition of the CPS allowed pedestrians to individually determine whether they had enough time to cross the crosswalk.
Technically, at the time of this research (2015), it was a violation of the Uniform Vehicle Code and Model Traffic Ordinance—commonly referred to as the UVC(7)—to cross when the FDW was present. Work was underway to revise the UVC, however. One option considered was to remove the rule indicating that pedestrians could not start walking during the FDW and then replace it with a statement that pedestrians that start to cross after the start of the countdown must finish crossing before the appearance of the signal's solid hand. This change would need to be accompanied by a change in the Manual on Uniform Traffic Control Devices (MUTCD)(8) and State and local laws that specify allowable pedestrian behaviors—when facing various traffic control device displays.
The purpose of this study was to conduct two human factors field studies examining the utility of the presence of the Flashing Don’t WALK (FDW) icon (i.e., the flashing hand) during the countdown pedestrian signal (CPS). Phase I examined pedestrians’ comprehension of the CPS with and without the FDW signal, and the effect of removing the FDW on pedestrians with low vision. Three results were found: pedestrians were more likely to consider crossing with the CPS Alone than with the CPS + FDW; healthy, young participants had little difficulty judging the time required to cross for three different distances without changing their speed; and the removal of the FDW from the CPS + FDW signal had no negative impact on low-vision pedestrians’ decisions to cross during the CPS.
Phase II further evaluated the effect of removing the FDW from the CPS by observing pedestrians’ natural behavior at two intersections. Participants were naturally observed pedestrians at two intersections. Following a baseline period, the FDW was removed from the CPS signal. Data were collected immediately after FDW removal and six months later. Regardless of the CPS present, pedestrians were likely to begin crossing during the pedestrian change interval. Finishing times show significantly fewer people in the crosswalk after the cross-traffic was released at three of the four sites during the CPS alone follow-up condition than during the CPS + FDW condition. |