Intuitively Understood Pedestrian Signal Indications
In an increasingly complex pedestrian environment, where pedestrian signal phases may not be concurrent with vehicular green, use of pedestrian signal indications is necessary. Safe initiation of crossings requires that pedestrians be able to locate, see, and accurately interpret information provided by pedestrian signals.
Even though the pedestrian change interval signal indication consisting of a Portland orange flashing hand has been required since a 1977 change to the Manual on Uniform Traffic Control Devices (MUTCD), and informational signs are often posted by pedestrian push buttons, the general public still seems to be confused by the signal as an indication that allows them to continue to cross the street (Yauch & Davis, 2001). Tidwell and Doyle (1995) found that almost half of survey participants believed that the flashing DON’T WALK or hand indication meant that pedestrians should return to the curb if they had just started crossing.
"When the flashing DONT WALK was chosen in the 1960s, a more intuitive display would have been a flashing WALK. But part of the country already used the flashing WALK to warn motorists of a possible vehicular conflict during the display. So a counter-intuitive flashing DONT WALK was chosen to tell people to continue walking to finish their crossing. In 45 years we have not succeeded in making pedestrians understand this signal. It’s time to try something more intuitive!" (David Kuemmel, archivist for Signals Technical Committee, National Committee on Uniform Traffic Control Devices [NCUTCD.])
Yauch and Davis (2001) called for action: "The profession…needs to start fresh to develop a device that can provide a clear and simple meaning for a pedestrian to know when it is safe to cross a street." They acknowledged that "Pedestrian signals have to be understood by the youngest of children who may be walking to school, by seniors who may have physical conditions that restrict their sight, hearing and ability to walk, the physically disabled, and by individuals who may not speak or read English."
Is there a more intuitively understandable symbol and color to be used during the pedestrian change interval, and how large do symbols and numerals need to be to be legible and understandable to children, seniors, pedestrians who do not read English, and pedestrians with mild to moderate levels of visual impairment? Much of the Asian world, Great Britain and now Mexico are currently using either the GREEN MAN or WHITE WALKING MAN in a flashing or "automation mode" -- where the legs of the symbol look to be moving quickly, to indicate the pedestrian change interval. Often this indication is combined with a countdown display to further emphasize the clearance indication. The use of these displays may be a more intuitively understandable indication for the pedestrian clearance interval than the current United States standard.
Research is urgently needed to determine optimal pedestrian signal symbols, colors and sizes to enable most people who travel based on visual information to accurately discriminate the interval displayed as well as to read a countdown indication.
Pedestrian signal research as summarized in Yauchi, P. and Davis, R. (2001) leaves many questions unanswered. With regard to pedestrian countdown signals, research indicates high approval of a display in which the change interval is indicated by a countdown displayed at the same time as the flashing upraised hand. Studies comparing pedestrian crossing behavior with conventional signals versus pedestrian countdown signals have largely found that while more pedestrians begin crossing later in the pedestrian phase with countdown signals, the proportion of crossings on which pedestrians are still in the traveled way by the onset of opposing vehicular green does not increase. Correct understanding of countdown signals is generally found to be as good as or better than that of traditional signals, and pedestrians typically prefer countdown signals over traditional signals (Botha, J. et al., 2002; DKS Associates, 2001; Eccles, K., Tao, R and Magnum, B., 2004; Huang, H. and Zegeer, C., 2000; Markowitz, F., Sciortino, S., Fleck, J., and Yee, B., 2006). In all of this research the countdown signal was displayed during the change interval (only) and consisted of the countdown plus the traditional flashing upraised hand.
As a result of this research, the following requirement for countdown signals was added to the MUTCD in 2009. **
"Section 4E.07 Countdown Pedestrian Signals
01 *All pedestrian signal heads used at crosswalks where the pedestrian change interval is more than 7 seconds shall include a pedestrian change interval countdown display in order to inform pedestrians of the number of seconds remaining in the pedestrian change interval." *
03 *Where countdown pedestrian signals are used, the countdown shall always be displayed simultaneously with the flashing UPRAISED HAND (symbolizing DONT WALK) signal indication displayed for that crosswalk. *
04 *Countdown pedestrian signals shall consist of Portland orange numbers that are at least 6 inches in height on a black opaque background. The countdown pedestrian signal shall be located immediately adjacent to the associated UPRAISED HAND (symbolizing DONT WALK) pedestrian signal head." *
Singer and Lerner (2005) found in a small study carried out in one metropolitan area, that a pedestrian change interval display consisting of the countdown and no flashing upraised hand may result in less confusion. However, this display resulted in more delay in beginning to cross, and a higher number of crossings completed during steady don’t walk. While it did include participants (n=45) in three age groups in the experiment on signal comprehension, and analyze video-data from field testing by estimated age group, no attempt was made to examine the effects of the two display types on pedestrians with different levels of vision.
Zegeer et al. (1983) found that the use of the DON’T START in YELLOW clearance indication was found to be a significant improvement over the existing FLASHING DON’T WALK indication in terms of reducing pedestrian crossing violations and associated pedestrian-vehicular clearance related conflicts.
Scott et al. (2013) found that pedestrians with simulated visual acuity of 20/100 (well above legal blindness), could correctly read countdown displays comprised of 9" or 12" high symbols or numerals on only 6.5% to 58.5% of trials. They failed to correctly discriminate the phase of the signal on 13% of trials. Note that MUTCD 4E.07 permits the use of 6" high symbols for crossings up to 100’, so it is likely that numerals cannot be read by pedestrians with 20/100 acuity or less for many crossings under the current standard and that there are many situations in which the phase of the signal is not correctly discriminated. For pedestrians with simulated visual acuity of 20/300 (considered "legally blind," but having sufficient vision to acquire information and to make judgments for street crossing based primarily on visual cues), performance on phase discrimination was little better than chance, and reading the countdown displays was essentially impossible.
Thus, the current situation is that we have requirements for pedestrian signal displays that are commonly misunderstood (although understanding may be improved with the addition of countdown signals to the flashing hand symbol), but many pedestrians are unable to correctly read or make crossing decisions based on these displays despite the fact that MUTCD 4E.04 Guidance says "Pedestrian signal head indications should be conspicuous and recognizable to pedestrians at all distances from the beginning of the controlled crosswalk to a point 10 feet from the end of the controlled crosswalk…."
Estimates derived from the National Health Interview Survey 2006 found 21.2 million adult Americans who reported trouble seeing, even when wearing glasses or contact lenses, 15.2 million of whom were over 65 years of age. A study of 900 people over the age of 55 found that 75% of participants over 85 years old functioned at the legally blind acuity level (20/200 or worse) (Brabyn, J., et al. 2000). Older pedestrians who are not specifically identified as visually impaired typically have decreased contrast sensitivity and visual acuity, reduced peripheral vision, and reduced "useful field of view," (Wilson and Grayson, 1980), all of which may affect their ability to use pedestrian signal information for crossing decisions. Twenty-five percent of older persons surveyed in Orlando, FL reported that they had difficulty seeing pedestrian signals (Bailey, S.S., et al., 1992). As baby boomers age, the number of seniors with vision loss will continue to grow substantially. This increasing population of pedestrians who have trouble seeing, but who nonetheless travel primarily on the basis of visual sensory information, cannot be disregarded in decisions about pedestrian signals.
The fundamental concern regarding pedestrian signals is that they enable pedestrians to make good decisions about when to begin crossing in the presence of an environment characterized by moving vehicular traffic, and many visual distractions. Yet no empirical research on legibility and understandability of various pedestrian signal displays has been found that was conducted under conditions that require decision-making in the presence of conditions typical at signalized intersections.
Review international practice with regard to pedestrian signal indications, as well as research documenting those practices.
Conduct human factors research to determine the most intuitive, best understood indication to show the pedestrian change interval, and determine the optimal size of symbols and numerals to maximize legibility and correct decision-making by children, seniors, and people with mild to moderate levels of visual impairment in the presence of conditions typical at signalized intersections.
Results of this research will lead to MUTCD Standards and Guidance that will result in improved safety in crossing decisions by pedestrians, including children, seniors, and those having varying amounts of vision.
The financial impact is expected to be minimal to local authorities, as it may be accomplished over time, as equipment requires upgrading. Current control equipment is being manufactured to allow for a flashing walking person since the industry is selling their controllers worldwide. Implementation may be funded through safety grants. The use of a three color pedestrian head will require modification of the signal internal LED array and will be more expensive if that indication is deemed best by the research.
Bailey, S.S., Jones, S.A., Stout, R.J.., Bailey, J.H., Kass, S., and Morgan, B.B. (1992, Issues of elderly pedestrians. Transportation Research Record 1375.
Botha, J., Zabyshny, A., Day, J. et al.(2002) Pedestrian countdown signals: An experimental evaluation, Volume 1. San Jose State University Department of Civil Engineering and City of San Jose Department of Transportation.
DKS Associates, (2001). San Francisco pedestrian countdown signals: Preliminary evaluation summary. San Francisco, CA: San Francisco Dept. of Parking and Traffic.
Eccles, K, Tao, R and Magnum, B. (2004). Evaluation of pedestrian countdown signals in Montgomery County, Maryland, Presented at TRB, 2004.
Huang, H. and Zegeer, C. (2000). The effects of pedestrian countdown signals in Lake Buena Vista, University of North Carolina Highway Safety Research Center for Florida Department of Transportation.
Zegeer, C., Opiela, K., and Cynecki, M., Pedestrian Signalization Alternatives, University of North Carolina Highway Safety Research Center for Federal Highway Administration, FHWA/RB-83/102, 1983
Markowitz, F., Sciortino, S., Fleck, J., and Yee, B. (2006). Pedestrian countdown signals: Experience with an extensive pilot installation, ITE Journal, January 43-48.
Scott, A. C., Atkins, K. N., Bentzen, B. L., & Barlow, J. M. (2012). Visibility of pedestrian signals by pedestrians with varying levels of vision. Transportation Research Record: Journal of the Transportation Research Board, No. 2299, 57-64. doi:10.3141/2299-07.
Scott, A.S., Swenson, L.J, Bentzen, B.L.& Barlow, J.M. (2013). Effect of countdown-only pedestrian change interval displays on signal recognition by pedestrians with reduced visual acuity. Transportation Research Record: Journal of the Transportation Research Board, accepted for publication.
Singer, J., and Lerner, N. 2005. Countdown pedestrian signals: A comparison of alternative pedestrian change interval displays, Final Report to FHWA.
Wilson and Grayson, (1980). Age-related differences in the road crossing behavior of adult pedestrians, Publication No. TRRL-L-933, Transport and Road Research Laboratory, Crowthorne, England, 1980
Yauchi, P. and Davis, R. (2001) Pedestrian signals—A Call to Action, ITE Journal, April 2001, 32-35.
Task 1. Review of international practice and the research on which it is based.
Task 2. Conduct human factors research on the ability of children, seniors, and people with mild to moderate levels of visual impairment to quickly and accurately determine the implications for action of least the following pedestrian change interval displays: Traditional display (flashing upraised flashing ORANGE hand alone); Traditional display ( flashing upraised ORANGE hand with ORANGE countdown numbers); New display ( ORANGE countdown only); New display (flashing WHITE “walking” man alone); New display (flashing WHITE “walking” man with WHITE countdown numbers); New display (flashing-animated “running” WHITE walking MAN alone); New display (flashing-animated “running” WHITE walking man with WHITE countdown numbers); New display (flashing-animated “running” YELLOW walking man with YELLOW countdown numbers; New display (flashing-animated “running” WHITE then YELLOW walking man with countdown numbers to impart when it is reasonable to continue to cross and change color during the last few seconds (maybe equal to the vehicular clearance) when the crossing pedestrian must clear the crossing, but must not start.
Task 3. Using the "best" indications identified in Task 2, conduct human factors research on the height of symbols and numerals that is necessary to enable pedestrians with mild to moderate levels of visual impairment to quickly and accurately determine the implications for action, under conditions typical of crossings at signalized intersections.
Task 4. Prepare a Final Report including implications for MUTCD 4E.
|Sponsoring Committee:||ACH40, Human Factors of Infrastructure Design and Operations
|Research Period:||24 - 36 months|
|RNS Developer:||Richard Nassi (Rnassi1@gmail.com), Charlie Zegeer, Ray Pusey, George Butzer, David Kuemmel, Billie Louise Bentzen|
|Index Terms:||Pedestrian movement, Pedestrian signs, Cognition, Signalized intersections, Visualization, Symbol signs, Flashing traffic signals, Pedestrian safety, Manual on Uniform Traffic Control Devices, Traffic control devices, |
|Cosponsoring Committees:||AME50, Accessible Transportation and Mobility|
Pedestrians and Bicyclists|
Operations and Traffic Management
Safety and Human Factors