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SYMBOL
SIGNING FOR OLDER DRIVERS
Publication No. FHWA-RD-94-069
July 1997
PREFACE
There has been
an increasing use of symbols, including those on highway signs, over
the past 2 decades. At the same time, there has been a rapid growth
in both the numbers and proportions of older drivers. Research on symbols
has shown that many symbols are poorly understood and/or difficult to
recognize at a distance, especially by older drivers. In spite of the
considerable research on traffic sign symbols, there has not yet been
a thorough evaluation of all symbols used on U.S. highways.
This report presents
a review of the literature on information processing abilities of older
drivers and human factors research on traffic sign symbols. It describes
a series of studies, surveys, and laboratory experiments that examined
symbols in the U.S. Manual on Uniform Traffic Control Devices (MUTCD).
Initially all symbols in the Manual were evaluated for comprehension
and daytime legibility distance among drivers of all ages. This was
followed by evalation of a set of 18 symbols using measures of nighttime
legibility (with and without glare), reaction time, glance legibility,
and conspicuity. Older drivers were found to have poorer understanding
of the symbols, as well as shorter legibility distances, higher glance
legibility thresholds, reaction times, and conspicuity search times.
Glare was found to reduce legibility of signs only for older drivers.
Modifications and redesigns to 13 of the symbols resulted in better
understanding of 3 symbols and increased legibility of 11 new designs.
Understanding and legibility of five novel symbols which were developed
for this project were found to be comparable to those of the redesigned
symbols.
Recommendations
were made for changes to specific symbols and guidelines were proposed
for the design of symbol traffic signs. A proposal was made for the
use of design optimization techniques, using computer, in the development
and evaluation of signs.
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Technical Report Documentation
Page
1. Report No.
FHWA-RD-94-069
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2. Government Accession
No. |
3.
Recipient's Catalog No. |
4.
Title and Subtitle
SYMBOL SIGNING
DESIGN FOR OLDER DRIVERS
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5.
Report Date
July 1997
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6. Performing Organization
Code |
7.
Author(s)
Robert Dewar,
Donald Kline, Frank Scheiber, and Allen Swanson
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8. Performing Organization
Report No. |
9.
Performing Organization Name and Address
Swanson Transportation
Consultants, Ltd.
P.O. Box 83001, Canyon Meadows Post Office
Calgary, AB Canada, T2W 6G8
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10. Work Unit No.
(TRAIS)
3B3a0202
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11. Contract or Grant
No.
DTFH61-01-C-00018
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12. Sponsoring Agency
Name and Address
Office of Safety
and Traffic Operations R&D
Federal Highway Administration
6300 Georgetown Pike
McLean, VA 22101-2296
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13. Type of Report
and Period Covered
Final technical
report June, 1991 June, 1994
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14. Sponsoring Agency
Code |
15.
Supplementary Notes
Contracting Officer's
Technical Representative (COTR) : Dr. Truman Mast HSR-30
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16. Abstract
This project evaluated
the effectiveness of symbol traffic signs for young, middle-aged and
elderly drivers. Daytime legibility distance and comprehension of 85
symbols in the Manual on Uniform Traffic Control Devices (MUTCD) were
measured. Legibility distance under night and night-with-glare conditions,
glance legibility, reaction time and conspicuity were measured for 18
of these symbols. Selected symbols were modified or redesigned and five
novel symbols were designed, using an image-processing iterative filterredesign
approach. These new signs were evaluated on measures of comprehension
and legibility distance under day, night and night-with-glare conditions.
Of the 85 symbols many were well understood, but 10 were understood
by fewer than 40% of drivers. Increased driver age was associated with
lower comprehension levels and legibility distances (under all test
conditions), as well as higher glance legibility thresholds, reaction
times and conspicuity search times. Modifications and redesigns to the
symbols resulted in better understanding of three messages and improved
daytime legibility distances of 11 of the new signs. Glare reduced legibility
of the signs only for the elderly drivers. Recommendations were made
for changes to specific symbol signs. Guidelines were proposed for the
design of symbol traffic signs, and a proposal was made for design optimization
techniques to be employed in the future development and evaluation of
such signs.
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17. Key Words
symbols, traffic
signs, comprehension, Legibility distance, glance legibility, reaction
time, conspicuity, older drivers, night legibility, glare
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18. Distribution
Statement
No restrictions.
This document is available to the public through the National Technical
Information Service, Springfield, Virginia, 22161.
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19. Security Classif.
(of this report)
Unclassified
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20. Security Classif.
(of this page)
Unclassified
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21. No. of Pages
282
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22. Price |
Form DOT F 1700.7 (8-72)
Reproduction of completed page authorized
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