Original Research Plan. Visual Acuity. Revised Research Plan. Analysis of Potential for Enlarged Pedestrian Countdown Signals

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1 Analysis of Potential for Enlarged Pedestrian Countdown Signals John A. Molino (SAIC) Bryan J. Katz (SAIC) Jason Kennedy (SAIC) TCD Consortium PFS Annual Meeting Hilton Head, SC, May 3-4, 2007 Original Research Plan Analytical Portion Acuity Legibility Conspicuity Specifications Low Vision Empirical Portion Observe Experimental Test Versions Las Vegas Conduct Cursory Informal In-situ Evaluation Revised Research Plan Analytical Portion Unchanged Empirical Portion Wait for Resolution of Las Vegas Test Observe Local Standard Versions Metro DC Area Investigate Construction of Enlarged Single Digit Mockup Visual Acuity Methods of Measurement Snellen Chart Landolt C Spatial Frequency Normal Value Snellen: 20/20 is 9 mm (0.34 in) letter at 20 ft Visual Angle (entire letter) = 5 minutes of arc Visual Angle (letter parts) = 1 minute of arc

2 Legibility FHWA, VMS: 40 ft per inch of text height ANSI Z535.2 Sign Standard: Favorable Viewing: 25 feet per inch Unfavorable Viewing: feet per inch FHWA, VMS: Visual Angle = 15 minutes Conspicuity Advertising Industry Sign as Silent Shout Seen 90 % of time for observation time (250 ms) anywhere in visual field US Sign Council: 17.5 feet per inch for pedestrian signs Contrast an important factor Specifications Countdown Digit Height MUTCD: 6-inch and 9-inch digits State Specs: 7-inch and 9-inch digits 9-inch digits measured locally Las Vegas experiment: 12-inch digits Color Walking Man White Raised Hand Portland Orange Specifications (Continued) Minimum Luminance in cd/m 2 ITE States Walking Man 2,200 5,300 Raised Hand 1,400 3,750

3 Low Vision Leading Causes: Diabetic Retinopathy 5.3 million Americans Age-related Macular Degeneration 1.6 million Cataracts 20.5 million Americans Glaucoma 4.2 million Americans AFB: 10 million people in US are blind or visually impaired Low Vision (Continued) 6.6 million Americans cannot read signs at normal distances Visual Impairment: 20/40 or less WHO defines Low Vision: 20/70 to 20/400 US Legal Blindness: 20/200 or worse; less than 20 degree visual field Implications Conservative Mace: maintain 40 feet per inch maximum Consider costs to implement Liberal Cover entire impaired vision range: from 20/40 to 20/200 Ten fold increase from 20/20 to 20/200 Possible Need for Enlarged Countdown Digits Present Capabilities Nine-inch Digits Traditional Legibility = 40 ft per inch Normal Visibility Distance = 360 feet Extremely Visually Impaired = 36 ft Equivalent to 3 Lane Road

4 Example of Local 9-inch Pedestrian Countdown Signal Local Measurements McLean, VA Local Luminance Measurements in cd/m 2 Local Legibility Measurements - DC Luminance of Raised Hand McLean, VA PR 650 Spectral Radiometer 2 deg. spot 3,817 cd/m 2 from 69 feet 4,329 cd/m 2 from 12 feet LMT L1009 Luminance Meter 1 deg. spot 4,150 cd/m 2 from 69 feet 7,536 cd/m 2 from 12 feet Distance, ft Morning, 9 AM Very Difficult Easy Very Easy Sharp Night, 9 PM Impossible Very Difficult Easy Very Easy Minor Blooming

5 Visit to Las Vegas, NV One Selected Site for Enlarged Pedestrian Signals Meetings O.C. White, City Traffic Engineer Prof. Mukund Dangeti, UNLV Observations Planned installation locations for enlarged pedestrian countdown signal heads Other pedestrian safety improvements Crossing Activation Switch Wide, Complex Intersection

6 Ten Lanes of Traffic to Cross Difficult to Read Countdown Digits Conclusion Difficult for normal sighted person to read digits Impossible for seriously visually impaired person Should develop and study 12-, 15-, and 18- inch pedestrian countdown signals Need to work with vendors and cities