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New Font and Arrow for National Park Service Guide Signs

Authors:
  • Garvey and Associates
  • Meeker & Associates, Inc.

Abstract and Figures

Although highly legible, the National Park Service's (NPS) Clarendon font produces sign legends that can be 10% to 20% longer than those depicted in conventional sans serif fonts. Placing these wider signs on narrow park roads and in urban historic districts can be prohibitive. To address this problem, a project was initiated to create a new NPS Roman-style (i.e., serif) font that requires less horizontal sign space than Clarendon while improving sign readability and retaining Clarendon's unique signature quality. The present study also evaluated a set of guide sign arrows to select the most legible for use on NPS guide signs. Three candidate typefaces were developed for daytime and nighttime field evaluation with 72 older and younger subjects. From the results of the evaluation, a fourth font was created and field tested with 12 additional subjects. Words created with the fourth font (NPS Roadway) were 5% to 11.5% shorter than those created with Clarendon. Further, subjects were able to read these words at 10.5% longer average threshold legibility distances than the same words composed in Clarendon. The relative legibility of 12 candidate guide sign arrows was evaluated in an outdoor field study. Forty-eight subjects participated in the daytime, and 32 subjects viewed the arrows at night. There were statistically significant differences in legibility distance among the various arrow shapes. The arrow ultimately recommended for use on NPS road guide signs performed 18% better than the FHWA "standard arrow."
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Garvey, Chirwa, Meeker, Pietrucha, Zineddin, Ghebrial, and Montalbano
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Title: A New Font and Arrow for National Park Service Guide Signs
Authors:
PHILIP M. GARVEY (Corresponding Author)
The Pennsylvania Transportation Institute
The Pennsylvania State University
201 Transportation Research Building
University Park, PA 16802 – U.S.A.
Phone: (814) 863-7929
Fax: (814) 865-3039
email: pmg4@psu.edu
KINGSTON N. CHIRWA
Kingston Chirwa
Montana State University
Civil Engineering Department
Bozeman, MT 59717 – U.S.A.
Phone: (406) 994-7266
Fax: (406) 994-6105
Email: kchirwa@montana.edu
DONALD T. MEEKER
Meeker & Associates, Inc.
22 Rockwood Drive
Larchmont, New York 10538- U.S.A.
Phone: (914) 834-1904
Fax: (914) 834-1927
email: dtmeeker@meekerdesigns.com
MARTIN T. PIETRUCHA
The Pennsylvania Transportation Institute
The Pennsylvania State University
201 Transportation Research Building
University Park, PA 16802 – U.S.A.
Phone: (814) 865-9951
Fax: (814) 865-3039
email: mtp5@psu.edu
ABDULILAH Z. ZINEDDIN
Roads Department
Dubai Municipality (DM)
P.O. Box 67, Dubai - United Arab Emirates (UAE)
Phone: (971) 50-358-7140
Fax: (971) 4-227-2323
E-mail: AZZINEDDIN@dm.gov.ae
Garvey, Chirwa, Meeker, Pietrucha, Zineddin, Ghebrial, and Montalbano
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RAMY S. GHEBRIAL
The Pennsylvania Transportation Institute
The Pennsylvania State University
201 Transportation Research Building
University Park, PA 16802 – U.S.A.
Phone: (814) 863-1289
Fax: (814) 865-3039
email: rsg12@psu.edu
And
JAMES MONTALBANO
Terminal Design, Inc.
Brooklyn, New York - U.S.A.
Phone: (718) 246-7069
email:jamesm@terminaldesign.com
Word Count: 5,350
Tables and Figures: 10 x 250 = 2,500
Total: 7,850
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ABSTRACT
Although highly legible, the National Park Service's (NPS) Clarendon font produces sign legends
that can be ten to 20 percent longer than legends depicted in conventional san-serif fonts. Placing
these wider signs on narrow park roads and in urban historic districts can be prohibitive. To
address this problem, a project was initiated to create a new NPS Roman-style (i.e., serif) font
that requires less horizontal sign space than NPS Clarendon while improving sign readability and
retaining Clarendon’s unique "signature quality." The present study also evaluated a set of guide
sign arrows to select the most legible for use on National Park Service (NPS) guide signs.
Three candidate typefaces were developed for daytime and nighttime field evaluation,
using 72 older and younger subjects. Based on the results of the evaluation, a fourth font was
created and field-tested using 12 additional subjects. Words created with the fourth font (NPS
Roadway) were five to 11.5 percent shorter than those created with NPS Clarendon. Further,
subjects were able to read these words at average legibility distances 10.5 percent greater than
the words composed in NPS Clarendon.
The relative legibility of twelve candidate guide sign arrows was evaluated in an outdoor
field study. Forty-eight subjects participated in the daytime and thirty-two subjects viewed the
arrows at night. There were statistically significant differences in legibility distance among the
various arrow shapes. The arrow ultimately recommended for use on NPS road guide signs
performed 18 percent better than the Federal Highway Administration “Standard Arrow.”
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INTRODUCTION
In the summer and fall of 2002 traffic safety researchers from the Pennsylvania Transportation
Institute (PTI) at the Pennsylvania State University and graphic designers from Meeker and
Associates and Terminal Design conducted a series of studies to improve the visibility of
National Park Service (NPS) guide signs. Two distinct evaluations took place: the first was a
study to improve the font used by the NPS and the second assessed potential arrows forms for
use on NPS guide signs. The present paper describes the research objectives, rationale, results,
and conclusions from this research effort.
STUDY 1: GUIDE SIGN FONTS
Over the past 60 years, the legibility of highway sign fonts has been the subject of numerous
research projects (for a review of the literature see 1). Much of the early work was designed to
establish a standardized highway sign font (2, 3, and 4), while later work focused on testing that
font using modern retroreflective materials and older drivers (5, 6, and 7).
Recently, researchers have questioned the continued effectiveness of fonts developed for
highway use in the 1940s and 1950s (8 and 9). These researchers developed and tested a new
sign font designed to be responsive to the use of modern high-reflectance sign materials, brighter
headlamps, and an increasingly older driving population. The result was the Clearview Typeface
for highway signs, which is legible at distances up to 15 percent further than those for the
comparable Standard Highway Alphabets. A similar effort was envisioned for improving the
NPS’s Clarendon sign font.
In 1966, the NPS instituted a standardized sign program for use at all NPS locations. The
intent of the program was to create a common visual identity for the service. Integral to this
graphic program was the use of the Clarendon typeface and the color brown for the background
of the signs and white for the sign copy.
Clarendon is a slab serif font that was designed in 1845 for use as a heavy face font for
emphasis in dictionary listings. It was used in the late 19th century in advertising and has the
characteristics of what are generally termed Egyptian typefaces, those arising during the period
in England that corresponded to the discovery of King Tutankhamen’s tomb. In a Memorandum
of Understanding to the NPS dated August 29, 1973, the Federal Highway Administration
(FHWA) sanctioned the use of the Clarendon font on NPS road guide signs in lieu of FHWA’s
Standard Highway Alphabet (4).
Although Clarendon is very readable in large sizes (5), the large slab serifs make for sign
legends that can be ten to 20 percent longer than conventional Roman typefaces. Placing wide
signs on narrow park roads and in urban historic districts is prohibitive; consequently letter
height is often reduced, compromising sign legibility.
In 1993, the NPS began a project to develop new sign and graphic standards for the
agency. Although the NPS wanted to retain the unique “signature quality” of the Clarendon
typeface as an integral part of their identity, the agency required a font optimized for both road
guide signs and print communications. Working with the graphic design consultants who
developed the Clearview Typeface system for the FHWA (8 and 9), four Roman (i.e., serif)
typefaces were identified to replace Clarendon: Century Old Style; Cheltenham; Sabon; and
Plantin. These are all classic Roman typefaces with an underlying structure that would allow a
signage version to be developed from the basic character of the fonts. However, since these
Roman typefaces were designed for printed text, the graphic designers believed they were too
thin-stroked for use on highway signs and would require modifications for road guide sign
applications. A signage version would have the appropriate stroke width in both the thin
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(horizontal), and thick (vertical) strokes of each Roman letterform while retaining the character
of the typeface design.
After careful study, the graphics design team hypothesized that the typeface Plantin had
attributes that could, if incorporated into a new type design in conjunction with Sabon, create a
more readable typeface when used on signs.
The result was a modern typeface influenced by, and true to, the earlier designs. The
serifs were thin, slightly cupped, and horizontal in orientation (instead of heavily bracketed as
with Clarendon) to reduce the mass created in the radius of a bracketed serif while retaining the
desired stroke width. Three variations of this font were developed for field evaluation; these
were called NPS-1, -2, and -3. Each of these typefaces had the same lowercase “x” height (i.e.,
height of the lower case letter form excluding ascenders and descenders) which closely matched
that of Clarendon (70.3 percent of the capital letter height). Although the three fonts were very
similar, there were differences designed into the fonts to help determine the effect of small
changes in stroke or letter width on sign legibility (Figure 1).
1. NPS Roadway 1 had a stroke width that was nearly equal to Clarendon (1.3 percent less)
and a nominal word length that was approximately 9.5 percent shorter than Clarendon.
2. NPS Roadway 2 had a stroke width that was slightly heavier (7.7 percent) than Clarendon
and a nominal word length that was about 9.4 percent shorter than Clarendon.
3. NPS Roadway 3 was designed with a 6.2 percent narrower stroke width than Clarendon
and letters condensed by five percent. The resulting word length was 14.1 percent shorter
than Clarendon.
EXPERIMENT 1
Motorists read signs in one of two ways. When motorists read a sign that displays unfamiliar or
unexpected words, they must identify each letter and then construct the word (10); this is known
as a legibility task. When motorists know what word they are looking for, all they need to do is
identify the overall shape or footprint of the word on the sign and compare that shape with a
mental image of the word they are looking for (11); in sign visibility research this is called a
recognition task. It should be expected that global word recognition would be accomplished at a
greater distance than individual letter recognition. Research supports that expectation (3) but also
demonstrates that manipulating letter characteristics (e.g., all-uppercase versus mixed-case) has a
different effect on recognition than it does on legibility (9). Therefore, to fully assess the
effectiveness of the fonts evaluated in this study, both legibility and recognition tasks were used.
Method
The study was a daytime and nighttime field evaluation of six fonts displayed on signs with
white retroreflective lettering on brown backgrounds. The evaluation took place at PTI’s test
track in August of 2001. Test subjects were seated in the front passenger seat of a test vehicle,
driven toward the signs, and asked to read each sign as soon as they were close enough to do so
accurately.
Subject Recruitment and Screening
Seventy-two subjects were paid 20 (U.S.) dollars each to participate in the one-hour test session.
All subjects held valid Pennsylvania driver’s licenses. Thirty-six subjects ranged from 19 to 30
years of age (mean = 24.3), and 36 ranged from 65 to 80 years of age (mean = 73.6). Each
subject’s high contrast, binocular, distance visual acuity was measured using a standardized test
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(Good-Lite Co. Model A Translucent Eye Cabinet). Subjects wore corrective lenses if necessary.
The range in acuity scores for the young was 6/5 to 6/9 (mean of 6/6) and for the older group 6/5
to 6/15 (mean of 6/8).
Variables
The dependent variables were legibility distance threshold and recognition distance threshold.
Recognition distance was defined as the maximum distance at which a subject was able to
correctly identify the location of a specified target word on a sign that contained three words.
Legibility distance was defined as the maximum distance at which a subject was able to correctly
read one of the remaining two words on that same sign.
The independent variables were font (NPS-1, NPS-2, NPS-3, Standard Highway Series
D, Standard Highway Series E(M), and NPS Clarendon), time of day (daylight and night), and
subject age group (young and old). Font was a repeated measures (i.e., within subjects) variable
while time of day and age group were non-repeated (between subjects). The words in the NPS
and Standard Highway Series E(M) fonts were displayed in mixed case (i.e., initial capital letter
followed by lowercase letters), while the words in Standard Highway Series D were all-
uppercase.
Site and Apparatus
The test site was PTI’s Test Track Facility. The test track is a two lane 1.6 k oval. To avoid
artificially truncating reading distances, the signs were placed at the end of a tangent section of
the test track allowing for 350 m of sight distance.
A single observation vehicle (a 1999 Plymouth Grand Voyager with halogen headlamps)
was used for all subjects. The signs were 1.2 x 1.2 meter aluminum sheets covered with Avery
Dennison Company’s T-6500 high intensity white sheeting and 4809 Series Brown Overlay Film
resulting in signs that had white words on a brown background. The retroreflective material was
microprismatic and conformed to ASTM Types III and IV minimum RA requirements. Each of
the words had a 125 mm capital letter height and, when mixed case was used, proportionally
sized lowercase letters. The panels were mounted on a flat wooden frame for presentation
purposes (Figure 2).
Procedure
Subjects were run individually. The subject was seated in the front passenger seat with an
experimenter in the driver seat. At night, the headlamps were set on low beam.
The observation vehicle was driven to the 350 m mark upstream of the sign and parked in
the center of the 4.6 m wide travel lane. The cart upon which the sign panel was mounted was
placed 2.3 meters outside of the edge line and the sign was raised to 2.3 m as measured from the
bottom of the sign to the pavement. This arrangement resulted in a sign with a lateral offset of
4.6 m to the right of the center of the observation vehicle. The sign was turned approximately
four degrees toward the shoulder to avoid specular reflections from the test vehicle’s headlamps
at night.
Each sign panel contained three place-names (Figure 2). Before each sign was shown, the
experimenter read aloud a place-name for the subject to find. With the observation vehicle
parked at 350 m, the sign was shown, and the subject attempted to find the target word and was
asked to respond by saying, “top,” “middle,” or “bottom.” The experimenter then drove the
vehicle toward the sign at approximately 10 to 20 kph until the subject correctly stated the target
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word position. The subjects were instructed to wait until they were certain of the target word
position; guessing was strongly discouraged.
The travel lane was marked every 1.5 meters. When the subject correctly located the target
word, the experimenter stopped the vehicle and recorded the distance as the recognition
threshold for that condition. The experimenter then indicated the position of one of the other
words on the sign (e.g., the “top” word) and asked the subject to read that word. The
experimenter then continued to drive the vehicle toward the sign until the subject correctly read
the indicated word. When the subject correctly read the target word, the experimenter stopped
the vehicle again and recorded the distance as the legibility threshold for that condition. The car
was then turned around and again parked 350 meters upstream of the sign. The procedure was
repeated until recognition and legibility thresholds for all six fonts were established. To avoid
learning or fatigue effects, the order of font presentation was counterbalanced across subjects.
Analysis and Results
Analysis of variance (ANOVA) found a significant main effect of font for the recognition
dependent variable (F=2.41, p=0.04), but there was no significant main effect of font on
legibility (F=0.46, p=0.81). No significant interactions were found between font and age group
or time of day for either recognition or legibility.
A Tukey HSD post-hoc test was performed on the font recognition data to determine
which of the six fonts were significantly different from the others in the recognition task. The
only significant difference was between Clarendon and Standard Highway Series D (p=0.01),
wherein the Clarendon font outperformed the all-uppercase Standard Highway Series D font by
17 m.
Discussion
That the newly designed NPS fonts did not result in statistically significant improvement in
either legibility or recognition indicates that these new fonts were not a substantial improvement
over Clarendon. However, descriptive statistics did hint that the new NPS fonts might be
producing small improvements in legibility distance; although at only about two to four percent
these were neither statistically nor practically significant. A second study was conducted to
evaluate a fourth NPS font, specifically designed to incorporate what the graphic designers
thought were the best features of NPS 1-3 with modifications to emphasize word shape that
included a heightened lower case letter height, simplification of letter form, and slightly
condensed overall font (Figure 1). This font was called NPS Roadway.
EXPERIMENT 2
Following a review of the Experiment 1 findings, the type designers suggested increasing the
lower case “x” height by 4.8 percent to 73.7 percent of capital letter height to allow for more
interior space in the letterforms and to make the typeface appear larger while maintaining the
same capital letter height. With additional changes to stroke width and letter spacing, this new
design resulted in word length that was 5 to 11.5 percent shorter than Clarendon (Figure 1).
Methodology and Procedure
The procedures and methodologies described in Experiment 1 were replicated in Experiment 2,
with some exceptions. Only two fonts were tested in Experiment 2: NPS Roadway and NPS
Clarendon. As there was no age group by font interaction (i.e., age did not affect ordinal ranking
of font visibility) in Experiment 1, the subject sample in Experiment 2 was restricted to young
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observers. To stay within the study’s budget, the number of subjects was reduced to twelve. To
increase the total number of observations, each font was replicated on six signs for a total of
twelve observations per subject or 72 observations per font in the day and night.
Analysis and Results
A MANOVA was conducted on the data to determine if there were any main or interaction
effects. Font was found to be a significant factor in sign legibility (F=6.02, p=0.02), but not
recognition (F=0.03, p=0.86). The mean legibility distance for NPS Roadway was 10.5 percent
greater than for NPS Clarendon (81 and 73 meters, respectively). Figure 3 depicts the combined
results of Experiment 1 and 2, plotting the relative legibility of all tested fonts against NPS
Clarendon.
STUDY 2: GUIDE SIGN ARROWS
Guide sign arrows play a pivotal role in the safe and efficient flow of traffic as they often are
placed at high demand “choice points” where there is a great deal of visual information to be
processed and integrated with vehicle handling responsibilities in a short period of time (12).
Central to an arrow’s effectiveness is the ease with which motorists can determine its orientation
(i.e., its legibility). The goal of Study 2 was to determine the most legible arrow style for use on
NPS guide signs.
While several studies have evaluated the effect of arrow style on traffic signal and lane
control visibility (e.g., 13, 14, and 15) and others have looked at the legibility of pavement
arrows (e.g., 16), there is little research guidance on selecting the optimum arrow for roadway
guide signs (12). Past research on arrow legibility, while not always directly relevant to the goal
of optimizing guide sign arrow legibility, however provides a useful background and framework
for achieving this goal.
Previous researchers (15) investigated the relationship between traffic signal arrow shape
and legibility in a series of lab experiments. These researchers found significant differences
between arrow shapes, however they found the choice of dependent measure (i.e., optical blur
versus contrast reduction) had a profound effect on arrow shape legibility ranking, a finding
emphasized in other reports (17). For example, some arrow shapes performed well when blurred,
but when contrast was reduced performed poorly. These researchers (15) concluded that while
“no simple choice of a ‘best’ arrow shape exists…the use of a wide-angled head and, less
certainly, a wide shaft” results in the most consistently superior legibility across dependent
measures. However, when these researchers replicated this lab study in a controlled field
environment (13), the results were less convincing. In this study, six arrows types were evaluated
under daylight and night conditions using reaction time as the dependent variable. With the
exception of the “ARRB (Australian Road Research Board) Design,” all the arrows were based
on the ITE (Institute of Transportation Engineers) design (separated shaft and head), which was
varied mainly in stroke width and shaft length for this experiment. In this more applied study;
arrow shape did not have a significant effect on legibility.
Another researcher (18) evaluated the visibility of directional arrows to be used as part of
exit signing in buildings. In one experiment, he evaluated 16 arrow shapes tested in positive and
negative contrast (Figure 4) under adverse visibility conditions (i.e., reduced luminance). Mean
errors in reporting arrow orientation was the dependent measure. Seven subjects viewed the slide
presentation. Under the most adverse stimulus luminance conditions this researcher found large
differences in arrow legibility. The best arrow shape resulted in an error rate of only 8.3 percent
(Arrow C) while the worst yielded 65.5 percent errors (Arrow N). Fifty-two subjects then
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subjectively ranked a subset of thirteen of the arrow shapes (Arrows F, J, and L of Figure 4 were
omitted). Conventional “head with shaft” arrows resulted in the highest rankings based on
“connotation of exit,” “appearance,” and “direction.”
Overall, this researcher found a strong relationship between legibility and arrow style, but
he had a difficult time generalizing exactly what makes one arrow more or less legible than
another. For example, in some cases the inclusion of a shaft improved performance while in
others it made the arrow less legible. In summarizing the visibility experiment, he stated,
“perhaps the main conclusion is that the arrow head should be the dominant graphic element.
The shaft may be useful in reinforcing the message, but should be a secondary feature.”
Combining the visibility and the ranking experiments he suggested the best arrows were A, B, C,
and M, with B emerging as the best overall choice.
In one of the few studies that investigated the effect of guide sign style on legibility (12),
seven arrow types were studied. Five of the arrows were delta-winged (Figure 5, Arrows 1, 3, 5,
6, and 7), with two being very similar to FHWA’s Standard Arrow (Arrows 3 and 5), and two
were “crow’s foot” type arrows (Arrows 2 and 4). Five subjects were shown eighty
tachistoscopic presentations (i.e., short durations ranging from 0.015 to 0.030 sec) in ten, two-
hour sessions.
Each of the arrows was orientated in one of the four cardinal directions. The subjects
were asked to identify the arrow orientation and to rate their response confidence. The dependent
measure was an “index of recognizability” derived from signal detection theory. These
researchers found a significant orientation effect, with the “north” orientation having the best
legibility. They found that an arrow with “a wasp-wasted fuselage, a slightly smaller arrow head
and a slightly longer shaft” (Arrow 1) showed “clear superiority.” The two that were similar to
the FHWA Standard Arrow were ranked third and fifth. The authors concluded that directional
information (i.e., arrow orientation) is contained in both the arrowhead and the shaft.
METHOD
Apparatus
Arrows
Twelve guide sign arrows (Figure 6) were evaluated in Study 2. These arrows included three
proposed by the NPS (i.e., Color Detour I and II, and Rounded Crow’s Foot) and one suggested
by the FHWA (i.e., FHWA Standard Arrow (M6-3)). The other eight included in the study were
arrows already in use by the FHWA (standard or with shaft modification) and arrow symbols
used for other route guidance applications. Arrow length for most styles was approximately 23
cm (9 in), with some deviation due to arrow design (Table 1). The twelve arrows were:
FHWA Arrows (4 and 19):
1. Down Arrow (6-3)
2. Down Arrow (6-3) with extended shaft
3. Standard Arrow (M6-3)
4. Camper Symbol Arrow (6-49)
“Crow’s Foot”:
5. Color Detour Arrow I - thin stroke
6. Color Detour Arrow II – thick stroke
7. Rounded Crow’s Foot Arrow
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8. Montreal Expo Arrow with short shaft (20)
Shaftless Arrows:
9. Winged Delta
10. Chevron
Other Arrow Styles:
11. Traffic Signal Head Arrow - Similar to the ITE design found to be “one of the
best” arrows (2), but with a more rounded head.
12. Serif Arrow – designed for this study to match the NPS serif font (Clarendon)
Retroreflective Materials
The signs were fabricated using the same white on brown materials used as in Study 1.
Test Site and Setup
As in Study 1, the evaluation took place at PTI’s test track. Test subjects were seated in the front
passenger seat the late model minivan described in Study 1. A single arrow was displayed at the
end of the 305 m tangent section of the test track. The van was located in the center of the 3.7 m
travel lane. The arrows were mounted to a frame using standard lateral and vertical offsets (8).
They were placed 1.8 m outside the roadway edge line, with the arrow raised 2.4 m as measured
from the bottom of the sign panel to the pavement. The immediate visual surround forming the
background, or external contrast, for the signs under daytime conditions was consistently green
leaves on trees (Figure 7).
Variables
The dependent measure was the threshold distance at which the subjects could correctly identify
arrow orientation (i.e., north, northeast, east, southeast, south, southwest, west, and northwest).
The independent variables were arrow style (12 levels), observer age group (younger and older),
and time of day (daylight and night).
Participants
Forty-eight subjects (24 younger/24 older) participated in the daytime sessions and thirty-two
subjects (16 younger/16 older) viewed the arrows at night. The subjects were paid 20 (U.S.)
dollars each for the one-hour session. All subjects held valid Pennsylvania driver’s licenses. The
forty younger subjects ranged in age from 20 to 36 (mean = 28), and the forty older subjects
ranged from 64 to 83 years of age (mean = 72). Each subject’s high contrast, binocular, distance
visual acuity was measured using same standardized test as in Study 1. Subjects wore corrective
lenses if necessary. The range in acuity scores for the young was 6/4.8 to 6/7.5 (mean of 6/5.1)
and for the older group was 6/4.8 to 6/15 (mean of 6/6.6).
PROCEDURE
Each subject was seated in the front passenger seat of the test vehicle. A single arrow was
displayed at the end of the 305 m tangent section of the test track. The experimenter drove the
van toward the arrow at a speed of approximately 8-16 kph, and the subject was asked to identify
the arrow’s orientation. They were told to respond only when they were “certain” they could do
so accurately; guessing was strongly discouraged resulting in a false alarm rate of less than five
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percent.
The threshold distance at which the subject was able to correctly identify the arrow’s
orientation was recorded as the measure of effectiveness. The van was then driven back to the
starting point, and a new arrow was displayed. This procedure was repeated until each of the
twelve arrow types had been evaluated. The order in which the arrow types and orientations were
presented was counterbalanced between subjects to avoid practice, fatigue, and arrow orientation
effects.
RESULTS
Orientation
An analysis of variance (ANOVA) revealed a significant main effect of arrow orientation (F(7,
864)=4.74, p<0.05). Subsequent post-hoc analyses revealed that the vertical orientations were
more legible than the obliques with the south, or downward, arrow position being the most
legible of all orientations. The ANOVA revealed no significant interaction between arrow type
and arrow orientation, indicating that any arrow type could be used to indicate any orientation
without loss in legibility distance, eliminating the need to inventory orientation-specific arrows
such as the FHWA Down Arrow (6-3). As orientation was counterbalanced across arrow types,
and there was no statistically significant interaction between orientation and arrow type, the rest
of the analyses were conducted with the data collapsed across orientation.
Arrow Style
There were no interactions between arrow style and any of the other variables, therefore the
discussion of the arrow style results are confined to main effects. The arrow style main effect
showed that there were significant differences in legibility distance between the various arrow
shapes (Figure 8). A Tukey-LSD post-hoc analysis was conducted to determine which of the
arrows performed significantly better than the others (Table 2).
FHWA Arrows
FHWA Down Arrow The FHWA Down Arrow “shall be used only for overhead guide signs to
prescribe lane assignment for traffic bound for a destination or route that can be reached only by
being in the designated lane(s)” (19). While on the highway this particular arrow is used mainly
in the downward position, the FHWA Down Arrow was tested in all eight orientations. The
FHWA Down Arrow was the second least legible of all the arrows tested.
FHWA Down Arrow with Extended Shaft When the shaft of the Down Arrow was increased
from 7 to 18 cm (extended version), it became the most legible arrow in mean ranked legibility
distance. The extended shaft Down Arrow was legible 31 percent further than the standard
FHWA Down Arrow, but it was still not significantly better than five other arrows that
subtended substantially less sign space. The Montreal Expo and Serif Arrows could fit in a 471
cm2 panel while Color Detour I and II, Rounded Crow’s Foot, and Traffic Signal Head all could
fit within an 523 cm2 panel. The FHWA Down Arrow with extended shaft would require a 703
cm2 panel, which represents a 35 to 49 percent increase in panel size for no appreciable gain in
legibility distance over the smaller arrows.
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FHWA Standard Arrow The shaft length of the FHWA Standard Arrow is adjustable (4). The
length chosen for this research was 10.5 cm, representing the arrow proportions of Directional
Arrow Auxiliary Sign M6-3 (19). This arrow resulted in a mean legibility distance that was third
to last in the ranking. It was as legible as the other four poorest performing arrows and
significantly less legible than seven of the other arrows. This is consistent with earlier findings
(12), where arrows similar to the FHWA Standard ranked 3rd and 5th out of seven tested.
FHWA Camper Symbol Arrow The arrow used in conjunction with the FHWA camper
symbol to indicate a septic dumpsite, ranked 9th. The only arrow that the Camper Symbol Arrow
significantly outperformed was the Winged Delta, which was the least legible overall. Other
researchers (15) found a similar arrow (with a thicker shaft) to perform poorly with optical blur,
but to hold up well under reduced contrast.
“Crow’s Foot Arrows”
Color Detour Arrows I and II The Color Detour Arrow is used extensively in Pennsylvania to
direct traffic from interstates to other roads that would be able to accommodate the heavy truck
traffic if the interstate is closed due to an emergency. Color Detour Arrow II had a 17 percent
wider stroke width than Color Detour Arrow I. Although there was no statistically significant
difference between the two arrows, they ranked 7th and 3rd with Color Detour Arrow I having a
nine meter longer mean legibility distance. An arrow of this type ranked fourth of seven in
earlier research (12).
Rounded Crow’s Foot Arrow The Rounded Crow’s Foot ranked fourth. No other arrow shape
was significantly more legible, and the Rounded Crow’s Foot was significantly more legible than
the four poorest performing arrows.
Montreal Expo Arrow As its name implies, the Montreal Expo arrow was originally designed
for use at the 1967 World’s Fair (20). This arrow ranked sixth overall, significantly
outperforming the bottom three arrows and providing statistically equivalent performance to the
remaining eight arrows. With a wider stroke width, this arrow type fell in the bottom half of the
arrows tested in earlier research (15) under both blur and reduced contrast conditions, while at
similar proportions to the one tested here was found by other researchers to perform in the top
three (18) and second (12).
Shaftless Arrows
Winged Delta The Winged Delta arrow had the shortest mean legibility distance of all the
arrow forms tested. This arrow performed significantly worse than nine of the other arrows.
Chevron The Chevron ranked eighth in legibility distance. The Chevron significantly
outperformed only two of the other eleven arrows: the Winged Delta and the FHWA Down
Arrow. Other research (15) found a similar symbol (with a narrower stroke width) to perform
well with optical blur, but poorly with reduced contrast, while another researcher (18) found a
wide stroke chevron to have the highest visibility score, and a thinner stroke chevron to rank
second to last out of the thirteen arrow shapes tested.
Other Arrow Styles
Traffic Signal Head Arrow This arrow was based on the turn symbol used in intersection
traffic signal heads. This segmented arrow ranked second overall, significantly outperforming
Garvey, Chirwa, Meeker, Pietrucha, Zineddin, Ghebrial, and Montalbano
13
five other arrow shapes and resulting in statistical equivalence with the remaining six. Previous
research (15) found a similar symbol (with a narrower stroke width and larger space between
shaft and head) to perform well with optical blur, but poorly with reduced contrast.
Serif Arrow The Serif Arrow was designed for this study to allow the researchers to evaluate an
arrow that typographically matched the serif Clarendon font used on NPS signs. The Serif Arrow
ranked fifth overall in mean legibility distance, significantly outperforming four other arrows and
achieving statistical equivalence with the remaining seven.
CONCLUSIONS AND DISCUSSION
The objective of this research was to design and test new fonts and arrows for use on NPS guide
signs. The NPS wanted a font that had the signature quality of the current NPS Clarendon font,
but provided greater visibility with a significantly smaller sign panel. The NPS Roadway font
developed for Study 1, Experiment 2 resulted in a 10.5 percent increase in legibility distance and
no loss in recognition distance while requiring 5 to 11.5 percent less sign width.
The FHWA has verbally endorsed the use of NPS Roadway on NPS guide signs. While
awaiting a formal sanction through a new Memorandum of Understanding between the FHWA
and the NPS, the NPS is currently testing the new font at several parks. NPS Roadway can be
found on signs in Mt. Rushmore in South Dakota, and at George Washington’s Birthplace in
Virginia. Several signs using the new font are also under production for use in Jewel Cave,
South Dakota.
Study 2 provided evidence that relatively small design changes (e.g., stroke width and
edge rounding) have little effect on arrow legibility. This was evidenced by the finding that
changing the stroke width of the Color Detour arrow did not significantly affect its legibility, and
that all arrows from Montreal Expo through FHWA Down Arrow extended shaft (Figure 8) had
statistically equivalent legibility.
Study 2 also showed that, while motorist age and time-of-day affect arrow legibility
distance; these effects are not arrow specific. In other words, arrow styles that are good for
young motorists work well for older motorists and arrows with good daytime visibility also
perform well at night.
Arrow orientation also had a significant effect on arrow legibility. The cardinal arrow
orientations (i.e. north, south, east, and west) had better legibility than the intermediate
orientations, but again, there was no interaction with arrow type. This signifies that the idea of
specific arrow styles for specific orientations (e.g., FHWA (6-3) “Down Arrow”) may not be
necessary or desirable.
In the end, Color Detour I was recommended to the NPS for use in their guide sign
system. The only arrow that performed better (a non-statistically significant 3.6 m) was the
FHWA down arrow with extended shaft, which subtends a 35 percent larger sign area.
Considering the overall poor performance of the FHWA arrows in standard form, the present
researchers are planning to further evaluate the legibility of these arrows.
REFERENCES
1) Garvey, P.M. and Kuhn, B.T. (2004). Highway sign visibility. Chapter in Handbook of
Transportation Engineering, M. Kutz, Editor. McGraw-Hill, New York, New York.
Garvey, Chirwa, Meeker, Pietrucha, Zineddin, Ghebrial, and Montalbano
14
2) Forbes, T.W. and Holmes, R.S. (1939). Legibility distances of highway destination signs in
relation to letter height, width, and reflectorization. Proceedings, Highway Research Board
Bulletin, 19, pp. 321-335.
3) Forbes, T.W., Moscowitz, K., and Morgan, G. (1950). A comparison of lower case and
capital letters for highway signs. In Proceedings of the Thirtieth Annual Meeting of the
Highway Research Board, pp. 355-373.
4) USDOT (2002). Standard highway signs: as specified in the MUTCD millennium edition.
U.S. Department of Transportation, FHWA. http://mutcd.fhwa.dot.gov/
5) Mace, D.J., Garvey, P.M., and Heckard, R.F. (1994). Relative visibility of increased legend
size vs. brighter materials for traffic signs. Federal Highway Administration Publication No.
FHWA-RD-94-035., Washington, DC.
6) Zwahlen, H.T. and Schnell, T. (1999). Legibility of traffic sign text and symbols.
Transportation Research Record, No. 1692, pp. 142-151.
7) Bentley, K., Hayes, E., Rick, M., and Schnell, T. (2001). Legibility distances of fluorescent
traffic signs and their normal color counterparts. Transportation Research Record No. 1754,
pp. 31-41
8) Garvey, P.M., Pietrucha, M.T., and Meeker, D. (1997). Effects of font and capitalization on
legibility of guide signs. Transportation Research Record, 1605, pp. 73-79. National
Academy Press, Washington, D.C.
9) Garvey, P.M., Pietrucha, M.T., and Meeker, D. (1998). Development of a new guide sign
alphabet. Ergonomics in Design. Vol 6 (3), pp. 7-11.
10) Tinker, M.A. (1963). Legibility of print. Ames, Iowa: Iowa State University Press.
11) Proffitt, D.R., Wade, M.M., and Lynn, C. (1998). Creating effective variable message signs:
Human factors issues. Final Contract Report, Project No. 9816-040-940, VTRC 98- R31.
25p. Virginia Department of Transportation, Richmond, VA.
12) Markowitz, J., Dietrich, C.W., Lees, J.W., and Farman, M. (1968). An Investigation of the
design and performance of traffic control devices. Bureau of Public Roads, U.S. Department
of Transportation, Federal Highway Administration, Washington, D.C. Contract No. CPR-
11-5955, Report No. 1726.
13) Bryant, J.F.M., and Smith, G. (1976). The shape of traffic signal arrows. ARRB
Proceedings, Session 25. Vol. 8, 36-45
14) Mace, D.M., Finkle, M., and Garvey, P.M. (1996). Requirements for visibility of symbolic
traffic signals. FHWA Final Report. Publication No. DTFH61-92-C-00034.
15) Smith, G. and Wier, R. (1978). Laboratory visibility studies of directional symbols used for
traffic control signals. Ergomomics, 21(4), 247-252.
16) Zwahlen, H. T., Schnell, T, and Miescher, S. (1999). Recognition distances of different
pavement arrow designs during daytime and nighttime. Transportation Research Record,
1692, 119-128
17) Carr, R. (1969). The legibility of signs. Print, 28-34.
18) Lerner N.D. (1981). Evaluation of exit directional symbols. National Bureau of Standards
Final Report, NBSIR 81-2268, Washington, D.C.
19) USDOT (2000). Manual on Uniform Traffic Control Devices Millennium Edition. U.S. DOT,
Federal Highway Administration. http://mutcd.fhwa.dot.gov/kno-millennium.htm
20) Arthur, P. and Passini, R. (1992). Wayfinding: People, signs and architecture. McGraw Hill,
New York, N.Y.
Garvey, Chirwa, Meeker, Pietrucha, Zineddin, Ghebrial, and Montalbano
15
LISTS OF TABLES AND FIGURES
TABLE 1 Study 2: Arrow Dimensions
TABLE 2 Study 2: Results of the Post-Hoc Statistical Analysis Comparing Pairs of Arrow
Styles
FIGURE 1 Study 1: Font development.
FIGURE 2 Study 1: Experimental apparatus.
FIGURE 3 Study 1: (Experiments 1 and 2) Percent change in legibility distance compared to
Clarendon.
FIGURE 4 Study 2: Arrow shapes tested by Lerner, 1981 (18).
FIGURE 5 Study 2: Arrow shapes tested by Markowitz, et al., 1968 (12).
FIGURE 6 Study 2: Arrow shapes used in current study.
FIGURE 7 Study 2: Day and night view of experimental stimuli.
FIGURE 8 Study 2: Mean legibility distances for guide sign arrow styles.
Garvey, Chirwa, Meeker, Pietrucha, Zineddin, Ghebrial, and Montalbano
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TABLE 1 Study 2: Arrow Dimensions
Arrow Style Shaft Length in cm (in) Head Width in cm (in)
Winged Delta 21.0 - head length (8.3) 16.5 (6.5)
FHWA Down Arrow (6-3) 17.5 (6.9) 24.8 (9.8)
FHWA Standard (M6-3) 23.8 (9.4) 17.2 (6.8)
FHWA (6-49) 28.5 (11.22) 10.5 (4.1)
Chevron 16.5-head length (6.5) 19.5 (7.7)
Color Detour II 23.0 (9.1) 23.0 (9.1)
Montreal Expo 23.8 (9.4) 17.5 (6.9)
Serif 24.0 (9.5) 20.0 (7.9)
Rounded Crow’s Foot 23.5 (9.3) 22.5 (8.9)
Color Detour I 23.0 (9.1) 23.0 (9.1)
Traffic Signal Head 23.2 (9.1) 23.2 (9.1)
FHWA Down (extended) 28.5 (11.2) 24.8 (9.8)
Garvey, Chirwa, Meeker, Pietrucha, Zineddin, Ghebrial, and Montalbano
17
TABLE 2 Study 2: Results of the Post-Hoc Statistical Analysis Comparing Pairs of Arrow
Styles
=
1
= =
>
2
= =
> > = =
> > > = =
> > > = = =
> > > > = = =
> > > > = = = =
> > > > > = = = =
> > > > > = = = = =
> > > > > > = = = = =
1
non-significant row/column comparison
2
row arrow significantly more legible than column arrow
NPS Clarendon v. NPS Roadway 1
1.4% Wider Stroke Width
7.7% Wider Stroke Width
6.2% Narrower Stroke Width
3.1% Narrower Stroke Width
9.5% Shorter Legend Length
9.4% Shorter Legend Length
14.1% Shorter Legend Length
11.5% Shorter Legend Length
Test Typeface
Clarendon
NPS Clarendon v. NPS Roadway 2
NPS Clarendon v. NPS Roadway 3
NPS Clarendon v. NPS Roadway 4
Standard Highway Series E(modified)
Standard Highway Series D
Garvey, Chirwa, Meeker, Pietrucha, Zineddin, Ghebrial, and Montalbano
19
FIGURE 2 Study 1: Experimental apparatus.
Garvey, Chirwa, Meeker, Pietrucha, Zineddin, Ghebrial, and Montalbano
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FIGURE 3 Study 1: (Experiments 1 and 2) Percent change in legibility distance compared
to Clarendon.
-20
-15
-10
-5
0
5
10
15
20
Percent Legibility Distance
Clarendon NPS-1 NPS-2 NPS-3 NPS
Roadway
Series
E(M)
Series D
Garvey, Chirwa, Meeker, Pietrucha, Zineddin, Ghebrial, and Montalbano
21
FIGURE 4 Study 2: Arrow shapes tested by Lerner, 1981.
Garvey, Chirwa, Meeker, Pietrucha, Zineddin, Ghebrial, and Montalbano
22
FIGURE 5 Study 2: Arrow shapes tested by Markowitz, et al., 1968.
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FIGURE 6 Study 2: Arrow shapes used in current study.
Winged Delta FHWA (6-49)
FHWA Standard (M6-3)
FHWA Down (6-3)
Chevron Color Detour II Montreal Expo Serif
Rounded Crow’s Foot Traffic Signal Head FHWA Down (with
extended Shaft)
Color Detour I
Garvey, Chirwa, Meeker, Pietrucha, Zineddin, Ghebrial, and Montalbano
24
FIGURE 7 Study 2: Day and night view of experimental stimuli.
Garvey, Chirwa, Meeker, Pietrucha, Zineddin, Ghebrial, and Montalbano
25
FIGURE 8 Study 2: Mean legibility distances for guide sign arrow styles.
(372 ft)
(378 ft)
(409 ft)
(414 ft)
(440 ft)
(453 ft)
(458 ft)
(474 ft)
(482 ft)
(482 ft)
(483 ft)
(494 ft)
90
100
110
120
130
140
150
160
170
Mean Legibility Distance (m
)
IJELBHDACFGK
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