Report No. FHWA-RD-75-118

STUDY OF THE NATIONAL STANDARDS FOR

DIRECTIONAL AND OTHER OFFICIAL SIGNS

Overview of Their Adequacy

l.V. Fechter and others

Institute for Applied Technology

National Bureau of Standards

U.S. DEPARTMENT OF COMMERCE

Washington, D.C. 20234

:Chter, J. V.^ Pezoldt, J., Persensky^ J. J

p''-^'^'^"^'^-- J. J., Lepkcvrski,, J. R

tuciy of the NationBl S' ras 1 or

October 1975

Final Report

Directional and other ciTicial signs. 0

vie;^; or their adequacy , Heoort Mo. FHkA -RD75-118, 75 pages (Avai le from the

National Technical Inforr.'S tion Service

Sprinfif ield, Va . , 22l6l, Oct. 1975).

This document is available to the public

through the National Technical Information

Service, Springfield, Virginia 22161

Prepared for

FEDERAL HIGHWAY ADMINISTRATION

Offices of Research & Development

Washington, D.C. 20590
NOTICE

This document is disseminated under the sponsorship of the

Department of Transportation in the interest of information

exchange. The United States Government assumes no liability

for its contents or use thereof.

The contents of this report reflect the views of the National

Bureau of Standards, Institute for Applied Technology, which

is responsible for the facts and the accuracy of the data

presented herein. The contents do not necessarily reflect

the official views or policy of the Department of Transportation. This report does not constitute a standard, specification, or regulation.

The United States Government does not endorse products or manufacturers. Trade or manufacturers' names appear herein

only because they are considered essential to the object of

this document.
Technical Report Documentation Page

1 . Report No. FaWA-RD-75-118

2. Government Accession No. 3. Recipient's Catalog No.

4. Title ond Subtl t! e STUDY OF THE X.ATIOXAL STANDARDS FOR DIRECTIONAL AND

OTHER OFFICIAL SIGNS. Overview of Their Adequacy.

S. Reoo" Date October 1975

6. Performfng OrQcr.'zC z~ Czce

8. PcfoTTiing C-aan.ra'ion Resc* No.

7. Author's^ j^^^ Fechter, Valom J. Pezoldt,

J. J. Persenskv, and J, Richard Lepkowski

9. Perforrring 0 -gen ' ic*' 0 " Nc^e zr^ Accress Institute for Applied Technology

National Bureau of Standards

Department of Commerce

Washington, D.C. 20234

i:. rtork Unit No. ^TRAIS) 32C2-082

p. 0. 5-3-0148

1^. 1 ype or Xezc-r arz r- e- zc ^ove-ed

12. Sponsoring Agency None and Access Final P.eport

Office of Research

Federal Highway Administration

Department of Transportation

Washington, D.C, 20590

^4. Sponsoring Agency Co-e

15. Supplementary Notes

FHI^A Contract Manager: T M. Mast, HRS-31

16. Abstract This report contains the results of an evaluation of the National Standards for

Directional and Other Official Signs (Part 21, Section 131(c), Title 23, United

States Code), It is the third in a series of three reports. The other reports

in the series are:

FHWA-RD-116 STLTDY OF THE NATIONAL STANDARDS FOR DIRECTIONAL AND OTHER OFFICIAL

SIGNS. Synthesis Report, Truman M. Mast, Office of Research,

Federal Highway Administration,

FHWA-RD-117 STUDY OF THE NATIONAL STANDARDS FOR DIRECTIONAL AND OTHER OFFICIAL

SIGNS. Laboratory Evaluation, A. G. Klipple and K. M. Roberts,

Office of Research, Federal Highway Administration

The results of an evaluation of the Standards conducted by the National Bureau of

Standards are presented in this report. The evaluation method made use of a literature review, two different theoretical models and expert opinion. It was concluded that for many speeds, sign locations, and driver characteristics, signs

conforming to the Standards but designed for extreme cases of message length and

content are inadequate.

17. Key *ords Sign Standards Evaluation, Directional

Signs, Sign Size, Sign Location,

18. Distribution Statement No restrictions. This document is available to the public through the National

Technical Information Service, Springfield,

Virginia 22161.

19. Security Ciassif. (of this report 20. Security Classif. (of this page 21. No. of Pages 22. =' '. ce Unclassified Unclassified 109

Form DOT F 1700.7 B-72 Reproduction of completed page authorized
Table of Contents

Page

Acknowledgements iii

Executive Summary "... iv

1.0 INTRODUCTION 1

1.1 1965 Highway Beautification Act 1

1.2 Objections to the Standards 2

1.3 FHWA/NBS Research Efforts 3

2.0 APPROACH 4

2.1 Review of Technical Material 4

2.2 Consultants 5

2.3 Development of Hypothetical Signs 5

2.4 Signing Models 11

2.5 Application of Models to Hypothetical Signs 16

3.0 RESULTS 16

3.1 Problem Areas in the Standards 16

3.2 Consultant Conclusions 17

3.3 Field Site Measurements 17

3.4 Sign Size, Legibility, and Theoretical Models 20

4.0 DISCUSSION 31

4.1 Problem Areas 31

4 . 2 Development of Theoretical Tests 31

4.3 Limitations of the Models 32

4.4 Conclusions and Recommendations 33

4.5 Recommended Research 34

Selected References . . „ 35

Appendix A - Sign Design Guidelines 41

Appendix: B - Summary of State Standards for Directional Signs . . 45

Appendix C - Photographs and Location Maps of Field Signs .... 49

Appendix D - Consultant Vitae 93

Appendix E - National Standards for Directional and Other Official

Signs

ii
ACKNOIMEDGBENTS

It would have been ijirpossible to conplete this project on such a rigid schedule without the valuable assistance of several other persons.

Miss .Ann Ramey contacted nunerous fims and officials to locate field

site information, state sign codes, and resource documents. Mr. Clarke Jones

prepared the state code sunmar>' after reviewing submitted material. Sign

design assistance was provided by \ir. Travis Brooks of FBvA..

The perseverance of Miss Kim Howard in t^-ping the text and preparing

tables for the original manuscript and its m^any revisions is much

appreciated. Mrs. Carol O'Connor and Miss Sharon Shaff also provided

valuable typing assistance throughout the reviev; process.

Consultants, Drs. T. Forbes, S. Hulbert, E. King, and T. Rocb^rell,

provided much information and active assistance on ver>' short notice.

Industry references and other material were proA'ided by Walt Youngblood

of the 3M Company.

>fe.jor inputs to the format and organization of the final report vrere made by Dr. Robert Cunitz, who contributed much time and effort to neld

the separate efforts of the several authors into a cohesive whole.

iii
EXECUTIVE SUMMARY

The Problem

In 1969 the Federal Highway Administration (FHIVA) issued National

Standards for Directional and Other Official Signs. Under these Standards,

certain features of directional signs erected by owners of privatelyoperated scenic and historical sites are controlled in a zone extending

frcm the edge of the right-of-way to a distance 660 ft (201.2 m) beyond.

The National Caves Association (NCA) objected to the Standards and

submitted requests for their modification. NCA sought increases in

-- total sign area,

-- height, and

-- length,

--as well as in the number of signs allowed.

In response to these NCA requests, the FHWA Office of Research:

- performed a study of the effects of angle of regard, and

- requested the assistance of the National Bureau of Standards (NBS)

to evaluate the Standards with respect to the needs of motorists

.

The Method

In fulfilling this request, NBS personnel have

- examined the present Standards

,

- searched data bases and reviewed pertinent literature,

- asked experts in highway- signing to independently evaluate the

Standards

,

- measured signs which were in compliance with the Standards , and

- developed 15 "worst case" sign designs which were evaluated by

two different theoretical models

.

iv
The Results

A review o£ the historv' of the development of the Standards uncovered

few references to technical supporting data and the published research on

highway signing v;as either too geiieral or not directly relevant.

Furthermore, evidence supplied by XCA. to support its proposed changes

was limited.

However, the literature did indicate that the ability of a driver

to read and comprehend a Directional Sign depends upon the following variables

-- driver's visual acuity (static and d)TLamic) ,

-- sign length, height, and placement,

-- vehicle speed,

-- local terrain,

-- driver eye and head movement,

-- message length, content, and arrangement, and

-- sign color and surrounding environmental conditions.

An analysis of the hypothetical signs was performed using reasonable

values for each of these variables. The analysis shovred that the sign

dimensions needed to display legible messages var)' considerably as the

2 2

values of each variable are changed. For example, a 30 ft (2.8 m ) sign

located 5 ft (1.5 m) from the pavonent would be adequate for drivers of

20/23 vision who were traveling at 40 mph (64.4 kphj , if a 40° divergence

angle v:as acceptable. At the opposite extreme, with the acceptable

divergence angle only 10°, a sign bearing the same message, located

740 ft (225.6 m) from the pavement and read by drivers traveling 80 mph

(128.7 kph) would h^ve to be over SOOO ft^ (742.2 m).

V
Stated in general form, the results indicate that:

-- most Standards -conforming signs are adequate if the divergence

angle is large, the speed is low, the lateral displacement small,

and the driver has 20/20 vision.

-- few signs are adequate for the same driver if the divergence

angle is small, the speed is high, and the lateral displacement

large.

-- few signs would he legible at the outermost edge of the controlled

zone (740 ft, 225. 6 m) .

The Conclusions and Recommendations

For many speeds, sign locations, and driver characteristics, signs

conforming to the Standards but designed for extreme cases of message

length and content are inadequate. Their utility depends on the values

of the "real world" variables used by FHWA as design criteria. Independent

of specifying such values, the following conclusions were reached:

-- The Standards should require that sign characters be legible at

the levels of visual acuity required by state driver licensing regulations.

-- Maximum sign size should be specified in terms of the visual

angle subtended, rather than as a maximum physical size.

-- Neither reviewed material nor consultant recommendations support

any change in the number of signs allowed, in the maximum distance

from sign location to site location, in the one-mile (1.6 hn)

spacing between signs, or in the proximity limits between

directional signs and interchanges or exits.

The consultants also made several recommendations ^>^ich could possibly

improve the Standards but which were unrelated to the question of adequacy.

vi
Research is needed to provide supporting data for changes to the

Standards. This research should include:

-- More field tests of sign legibility outside the right-of-way.

Field validation of laboratory studies and theoretical models.

-- Sur\'eys to define the actual visual acuity level of drivers.

Additional data are also required on:

-- Drivers' visual abilities, including the gestalt of sign

perception.

-- Drivers' information needs.

vii

An Overview of the Adequacy of National

Standards for Directional and Other Official Signs

1 . 0 Introduction

1.1 1965 Highway Beautification Act

In support of the 1965 Highway Beautification Act the Department

of Transportation in 1969 issued National Standards for Directional and

Other Official Signs (Part 21, Section 131(c), Title 23, United States

Code). As amended in late 1973, the Standards control outdoor advertising

signs, displays, and devices which are visible from highways in non -urban areas or are located within 660 ft ( 201 .2m) of the nearest edge of

the right-of-way in urban areas. These Standards limit signs outside

commercial areas and industrial zones to ". . . directional and other

official signs and notices, which signs and notices shall include, but

not be limited to signs and notices pertaining to natural wonders, scenic

and historical attractions, which are required or authorized by law, which

shall conform to national standards hereby authorized to be promulgated

by the Secretary hereunder, which standards shall contain provisions

concerning the lighting, size, number, and spacing of signs, and such

other requirements as may be appropriate to inplement this section . .

These Standards cover a variety of sign parameters ranging from

specific prohibitions to general guidelines. Of particular importance

are the following parameters

Size - The maximum dimensions allowed, including border and trim,

but not supports , are

Area - 150 ft^ (13.9 m^)

Height - 20 ft (6.1 m)

Length - 20 ft (6.1 m)

Spacing - The location of each directional sign must be approved by

the State liighway department and none can be located within

2,000 ft (609.6 m) of an intersection or exit along the

Interstate system or freeway, or within 2,000 ft (609.6 m)

of a rest area, parkland, or scenic area. These signs

must be within 75 air miles (120.7 km) of the activity for

the Interstate System and within 50 air miles (80.5 km)

for the Primary System. Such signs must be spaced at least

one mile (1.6 km) apart.

Number - No more than three directional signs for a given activity and

facing the same direction of travel may be located along

any single approach route to the activity.
Content - Message content on directional signs is restricted to

identification of the activity and directional information

such as mileage , route number or exit numbers

.

1.2 Objections to the Standards

A report from the Commission on Highway Beautification (1973) cited

numerous examples of businesses which were denied the privilege of erecting

signs in the protected zone - motels, restaurants, and points of interest.

The operators of such businesses were not satisified with the Act and have

criticized the Standards for being too restrictive. Others have criticized

the Standards for being too liberal and the National Caves Association (NCA)

,

an organization of private cavern owners who are permitted to erect

directional signs in the protected zones , has criticized the Standards for

being inadequate. The NCA objections to the Standards cited an anticipated

loss of income, an inability to relocate sites, and a heavy reliance

upon one-time visitors. The NCA proposed modifications to the size and

spacing (number) allowed, which would result in the following changes:

2 2 2 Area - from 150 ft (13.9 m J to a new maximum of 600 ft

(55.7 m^).

Height - from 20 ft (6.1 m) to 30 ft (9.1 m)

.

Length - from 20 ft (6.1 m) to 50 ft (15.2 m)

.

Spacing - from "Not more than three directional signs pertaining

(Number) to the same activity and facing the same direction of

travel may be erected along a single route approaching

the activity" to "Not more than six ..."

A letter from, a sign manufacturer was included as evidence of the

need for these changes. The letter referenced the dimensions needed to

display messages on signs located 660 ft (201.2 m) from the highway.

Full details were not provided, but a criterion of one inch (2.54 am) of

character height for every 40 ft (12.2 m) of viewing distance was used.

However, it was not clear how such figures were subsequently translated into

the larger physical dimensions of the signs requested by NCA.

An internal Federal Highway Administration (FHWA) study of these

objections cited a re-evaluation of the Standards by the Office of

Traffic Operations (FHWA Correspondence #T0-21, 1974). The requested

700% increase in area (from three to six signs and from 150 ft^ to

600 ft^ (13.9 to 55.7 m^) each) was considered excessive. However,

FHWA conceded that some messages could not be adequately displayed on

a 150 ft2 (13.9 m2) sign. For this reason, changes for freeways and

expressways were recommended by the Office of Traffic Operations in an

internal response to the Office of Right-of-Way and Environment, as follows

:

"Rather than to just place a limit on the size of the sign,

it is suggested that the limit be placed on the size for the

2
alphabets and the amount of directional information. For

example on freeways and expressways : (1) restrict the maximum

size of legend to 24-inch uppercase and 18 -inch lowercase

letters in the destination name and 18 -inch uppercase in the

directional copy, [2) limit the directional copy to two lines

not exceeding the width of the name of the attraction,

(3) utilize interchange numbers where appropriate, and (4) sign

size to be determined solely on legend size and spacing,

however, the maximum size sign shall not be greater than

400 square feet. Apply same criteria to other roads except

utilize 20 -inch uppercase/15-inch lowercase alphabets in the

attraction name and 15-inch uppercase in the directional

information. For these facilities the maximum size should be

limited to 300 square feet.

The current limitation as to the number of signs per approach

to the activity is adequate, in our opinion, for directional

guidance."

Official FHWA policy has not been modified to reflect these or other

internal responses to the question of adequacy.

Additional FHWA study of Standards modifications has emphasized problems

of implementing any changes . These studies indicate that active cooperation

with the states is absolutely necessary to meet the objectives of the

Highway Beautification Act of 1965. If the changes to Part 21 of the

Standards result in double standards for states to enforce, the "beautyprograms" would be in serious jeopardy. In addition to the problems

of double standards , should changes be made there is some question

about the legal status of the larger signs which are now scheduled to

be removed from highways.

1.3 FTIWA/NBS Research Efforts

In response to such questions regarding the adequacy of the Standards

,

the FHWA Office of Research initiated a human factors study of the importance

of divergence angle (the angle of regard between the direction of roadway

travel and the driver's line of sight to the sign) and requested the

assistance of the National Bureau of Standards (NBS) to complete an overview of the Standards' adequacy with respect to the needs of motorists.

It was the intention of Congress that the Standards allow adequate

guidance and information for motorists but that strict advertising be

avoided. Technical data which supported or conflicted with portions of

the Standards were sought.

To examine the adequacy issue, NBS personnel:

1 . reviewed the available FHWA files on this topic , discussed the

Standards ' history and problems with FHWA personnel , and prepared

the background material discussed above;

3
2. conpleted literature searches of recently published reports

relevant to highway signing, and obtained pertinent articles

for closer examination;

3. reviewed selected State Codes pertaining to privately- erected

directional signs;

4. completed field measurements of four signs in the Washington, D.C.

vicinity erected in compliance with the Standards;

5. asked four recognized experts in sign research to provide reviews

of the Standards and of research dealing with various specific

points

;

6. designed a variety of fictitious signs according to several criteria

and compared each with "real world" parameters; and

7. summarized the technical objections to specific parts of the

Standards and made recommendations to satisfy these objections.

2 . 0 Approach

It was the goal of this project to provide FHWA with an overview

of the adequacy of the 131(c) Standards - in terms of motorists' needs.

The limited time and resources and the restricted scope of the effort

permitted little original research to be done. Instead, a limited

literature search and review, discussions with and reports from

consultants, field site measurements, and two theoretical signing models

were used to evaluate specific points in the Standards.

2.1 Review of Technical I4aterial

A number of benchmark articles, annotated bibliographies and texts

were available which summarized a great deal of the early highway signing

research. To complement these publications, several data bases were

searched to identify more recent research.

The data bases examined were the:

- HRIS (Highway Research Information Service)

,

- NTIS (National Technical Information Service)

,

- Compendex (Engineering Index)

,

- PASAR (Psychological Abstracts Search and Retrieval) , and

- New York Times Information Service.

Unfortunately, most potential sources were either too general to

be applicable or were not directly relevant. Most research concerned

right-of-way signs - not directional signs positioned out of the

4
right-of-way. Advertising -sign literature was primarily concerned \\ith

attitudes o£ the public and advertising effectiveness, and was less

concerned \\ith layout, character height, or total area.

Section 21.4 of the Standards requires participating states to

submit their signing codes for review by FHIVA. Ten states have thus far

submitted the required material. Three other states in the Washington, D.C. area submitted their codes to this project for review. The extent of

compliance and magnitude of local exceptions were studied to identify

difficulties faced by states in implem.enting the Standards

.

2.2 Consultants

Four experts were selected whose published research dealt vdth subjects

relevant to parts of the Standards . (Brief vitae are included in

Appendix D.) These four men served to acquaint project personnel i\lth

relevant publications and different frames of reference to evaluate the

Standards . Each also responded to the question of Standards adequacy and

submitted a report summarizing their conclusions. The four were:

- Dr. Theodore Forbes [Professor of Psychology and Research Advisor,

Highway Traffic Safety Center at Michigan State University)

,

- Dr. Slade Hulbert (Research Ps>xhologist in the Psycholog}'

Department at the University of California at Los Angeles)

,

- Dr. Thomas Roclav"ell (Professor of Industrial and Systems Engineering,

Driving Research Laboratory at the Ohio State University) , and

- Dr. L. Ellis King (Associate Professor of Civil and Environmental

Engineering and Associate Director of the Center for Urban

Transportation Studies at the University of Colorado)

.

2.3 H>p)0thetical Signs

It was not possible to obtain a representative sample of actual signs

in the field for ccmparisons with the provisions of the Standards and ^\ith

published research. Consequently, h>pothetical signs were developed for

this purpose, based on established signing principles. Four actual signs

were measured to provide a frame of reference for evaluating the

hypothetical signs and to serve as examples of field problems and practices.

The message content and arrangements of these hypothetical signs

were selected to conform to the Standards, satisfy the guidelines

suggested in the >bnual on Uniform Traffic Control Devices (MUTCD, 19~1) , and present the extreme of dimensions likely to be encountered in the

field. It iv"as assumed that if the Standards were adequate for such

extreme cases, they would be more than adequate for signs of lesser

message length and content ^\hich were also better arranged.

r
A fictitious sign text was generated and arranged on two, three,

and four lines. In the previously cited FHWA study, the longest line

of text used was "SIX FLAGS OVER GEORGIA." To avoid direct criticism

of this or other existing signs, a fictitious name, "Schmillingrass

Caverns," was constructed which used the same number of characters and

spaces (i.e., 22). The recommendations (FHWA internal correspondence

#T0-21, 1974) mentioned above suggested that all text should occupy

only two lines on a sign. However, for the Six Flags example, text had

also been considered as three- and four-line arrangements. For these

reasons, comparable arrangements were used here. Figure 1 illustrates

upper and lowercase (UC/LC) and uppercase (UC) only examples of each

sign.

Each of these formats (two-, three-, or four-line) was arranged in

five configurations (based on MUTCD guidelines and research conclusions,

Kindersley, 1960)

:

-A) All UC characters, spacing between lines of text equal to

0.75 character height;

-B) All UC characters, SCHMILLINGRASS CAVERNS line(s) 1.5 times

the size of other line(s) , spacing between lines equal to

0.75 character height

;

-C) All UC characters, spacing between lines equal to 0.33 character

height (Kindersley, 1960) ;

-D) Same as configuration A, but with UC/LC characters;

-E) Same as configuration B, but with UC/LC characters.*

All characters are from Series E, as recommended by Standard Alphabets

(1966).**

For each of the 15 resultant signs, the length/height combination

which made best use of the available area was determined. The character

*Other specifications are discussed in Appendix A.

**The recommendation applies only to UC/LC characters but for consistency

Series E characters were used for UC only configurations as well.

6
Uppercase Only Upper and Lowercase

Sim 1

SCHMILL INGRES

CAVERNS

ROUTE 99

KENT ST EXIT

Schmillingrass

Caverns

Route 99

Kent St Exit

SCHMILLINGRASS CA\'ERNS

ROUTE 99 KENT ST EXIT

Sign 2

Schmillingrass Caverns

Route 99 Kent St Exit

SCHMILLINGRASS CA\TRNS

ROUTE 99

KENT ST EXIT

Sign 3

Schmillingrass Caverns

Route 99

Kent St Exit

Figure 1. Uppercase only and upper/lowercase versions of each of

the three signs.

7
height was calculated from these dimensions, as was the greatest distance

at which characters of that height would be legible. The method used is

illustrated below for a four- line sign in configuration A.

u • 7

1X . uu OLJTIM1 ijij J. 1N UrvrVOO

n / D

11

.

uu

0. 75

1. 00 ROUTE 99

0. 75

1. 00 KENT ST EXIT

0. 75

7. 75 lines of text

1) From Appendix A, if characters of unit size were used, the

length of the longest line would be 15.10 units.

2) Sign height, from the above diagram would be 7.75 units.

3) The ratio, a, of Length to Height would be

a = 15.10 = 1.95

7.75

which can be used to calculate the Height and Length of a sign of any fixed area since:

2 4) Area = Height x Length = Height x a Height = a Height .

2

5) In this example, for a 150 ft sign:

150 ft^ =1.95 Height^;

Therefore

,

Height = 8.77 ft (2.57 m) and

Length** = 150 ft^ = 17.10 ft (5.2 m)

Height

*The length of any sign is determined by the length of the longest line

of text which, in turn, depends upon the specific characters comprising

that line. For example, a line of 10 "m" characters would be longer

than a line of 10 "i" characters.

2 2

**The length/height ratio which made best use of the available 150 ft (13.9 m ) area (the optimum length/height ratio) was determined for each of the

15 signs. However, the optimum length for two- and three- line signs

exceeded the 20 ft (6.1 m) limit. Therefore, the height of these signs was calculated from the formula height = length/a = 20 ft/a.

8
6) The character height is equal to the sign height divided by

the number of lines o£ text. Hence,

character height = 8.77 ft = I.IZ ft (0.34 m)

7.75

OR

13.56 in (34.44 cm)

The factors which determine the greatest distance at which characters

are legible are the stroke width and the driver's visual acuity. For

reading purposes, visual acuity is the ability to distinguish letters on

a Snellen chart ( Bioastronautics Data Book , p. 638) . Persons of "normal"

vision (20/20 Snellen) can perceive characters having a stroke width of

.0698 in (.177 am) at a distance of 20 ft (6.1 m) . This corresponds to a one minute visual angle. Their visual acuity ratio is, therefore,

.00349 in/ft (.029 em/m) of viewing distance. As a general rule, the

distance at which characters are just legible is obtained by dividing

the stroke width by the visual acuity ratio . The just legible viewing

distances for various stroke widths are shown in Figure 2, for several

levels of visual acuity.

The legibility distance per unit of character height is obtained by

dividing the stroke width, expressed as a fraction of character height,

by the visual acuity ratio. In the example above, the stroke width of

UC only, Series E characters is 17.21 of character height.* For persons

with 20/20 vision, the legibility distance/character height ratio is

Therefore for our example the legibility distance is

13.56 in X 49.3 ft/in = 669 ft (203.9m).

That is, characters 13.56 in (34.44 am) high, whose stroke width is 17.2%

of character height, would be legible 669 ft (203.9 m) away to viewers

with 20/20 vision.

The legibility distance/character height ratio in the example above

(49.3 ft/ in, 5.92 m/om) is close to the "Rule of Thumb" ratio referred

to by numerous highway officials (50 ft/ in, 6 m/om) . As can be seen.

*Series E characters were used both for UC/LC and UC only signs, for

reasons of consistency. It should be noted, however, that Series E

UC/LC characters have a stroke width 19.9% of the character height,

while UC only characters have a stroke width 17.2% of the character

height. The larger stroke width makes UC/LC characters legible at

greater distances than UC only characters of the same height.

9
8.00 in

20.32 am

7.00 in

17.78 cm

6.00 in

15.24 cm

5.00 in

12.70 cm

'

4.00 in

10.16 cm

'

3.00 in

7.62 am

2.00 in

5.08 am

1.00 in

2.54 am

20/70

20/20

30o!o £t 400*. 0 £t 50o\o ft 600.0 ft

91.4 m 121.9 m 152.4 m 182.9 m

I \ I 700.0 ft 800.0 ft- 900.0 ft

212.4 m 243.8 m 274.3 m

Just legible viewing distance

Figure 2. Just legible viewing distance for various stroke widths

at four levels of visual acuity (figures based on visual

acuity alone, not in context of meaningful sign text).

10
use of the "Rule of Thumb" for placement of signs islth Series E UC only

characters rests on the unplicit assumption that most drivers have

20/20 vision. In fact, 80% of motorists drive with visual acuity

poorer than 20/20 (Derar, 19''5; Forbes, 1965). In seA'eral states

drivers may operate motor vehicles islth uncorrected vision of 20/40

or even 20/70 (King, 1970) . Ratios for four different levels of

visual acuity are given below for UC/LC (19.9% stroke -isldth) and

UC only (1~.2% stroke vridth) Series E characters.

Legibility distance per

unit of character height

Visual

Acuity

20/20

20/23

20/40

20/"0

Minimum

Discernible

Visual .Angle

1.00 min

1.15 min

2.00 min

3 . 50 min

UC/LC characters,

stroke 'isldth is

19.9% of character

height

57.0 ft/ in

6. 84 m/cm

49.8 ft/in

'- "Rule of Thirnib"

28.8 ft/in

J

.

46 m/cm

16.3 ft/in

1 . 96 m/cm

UC Only characters,

stroke width is

17.2% of character

height

49.3 ft/ in

5. 92 m/cm

^- "Rule of Thumb"

43.0 ft/ in

5.16 m/cm

24.9 ft/in

2.99 m/cm

14.1 ft/ in

1.67 m/cm

2,4 Signings Models

The models considered applicable to this project are those discussed by

King (19"1) and by Rocb-rell (19-3) . Both consider the effect of perpendicular

distance from the sign to the roadway (lateral displacsnent) , maximum

divergence angle, driver speed, sign width, (length), and number of words.

The lateral displacement partly determines divergence angle . At

smaller divergence angles, less lateral eye and head movem.ent is needed to

read the sign and foveal vision is not diverted as far from the roadway.

The divergence angle increases as the driver moves doun the road, from an

11
initial angle, measured at the point where reading begins, to a terminal angle (i.e., maximum divergence angle) , measured at the point

where reading ends. At any given speed, the terminal divergence angle

should be something less than half of the usable visual sector (i.e., the

right half of the field) . Early work by Hamilton and Thurstone (1937 , and

summarized by Ewald, 1971) indicated that the usable visual sector, in

which detail can be clearly seen, decreases in size with increasing speed.

At 30 mph (48.4 kph) , the visual sector is 90° wide while at 55.mph (88.5 kph)

it is reduced to approximately 48° . The miniinum size at higher speeds is

probably 20° to 30°, the normal limits of eye movement without corresponding

head movement.

In addition to its effect on visual sector width, increasing speed also

reduces the depth of that sector. At 60 mph (96.6 kph) a driver can see details

clearly only between 110 and 1400 ft (33.5 and 426.7 m) in front of the

vehicle (Ewald, 1971). This 110 ft (33.5 m) minimum fixes a limit to the

closeness of the sign. In other words, there is a minimum distance which

must separate drivers from a sign and this minimum increases with increasing

speed.

The following parameter values were used in applying the models to

the hypothetical signs:

Lateral Displacement -

5 ft (1.5 m), speed limit and similar types of signs are usually positioned at approximately this distance from

the pavement.

35 ft (10.7 m) , right-of-way signs are generally located

30-50 ft (9.1-15.2 m) from the pavement.

80 ft (24.4 m) , this is the "average" distance from the

pavement to the outermost edge of the right-of-way.

740 ft (225.6 m) , the zone protected by the Standards is from

the Bnd of the right-of-way to a point 660 ft (201.2 m)

beyond. 740 ft (225.6 m) is 660 ft (201.2 m) beyond the

"average" right-of-way.

Terminal Divergence Angle -

10°, King (1971) recommends 10° as the maximum angle, but his

discussion points out that other researchers favor 15°

;

both angles are close to the maximum divergence angle

expected of drivers who are using only eye movement to scan the visual field in front of the car.

30°, this angle was used since it was empirically determined in

eye movement research basic to Rockwell's (1973) paradigm

and is close to one-half of the field of view expected of

drivers moving at 55-60 mph (88.5-96.6 kph).

12
40° , this angle approximates the divergence angle bet^s-een the

^oad^^"ay and the position of the rear-vieiv mirror.

Speed -

80 mph (128.7 kph) , the speed for which most Interstate

highrays have been designed.

60 mph (96.6 Jq>h) , though the national speed limit is 55 mph

(88.5 kph) many drivers are likely to maintain this slightly

higher limit.

55 mph (88.5 kph), the national speed limit.

40 nph (64.4 kph) , the minimum speed limit on many highways.

Sign Length -

As indicated above, the sign length which made best use of the

available 150 ft- (IZ.S ^-y ras used for each version of the

four-line signs. Required viev.lng distances are identical for

all of the tis'o- and three- line signs because the length of

each had to be reduced to 20 ft (6.1 m) to conform with the

Standards

.

Number of V»"ords -

Published research [Forbes, 1939; 19"2) emphasizes the

desirabilit}' of using no m.ore than thjree or four short,

familiar ivords for best message perception. Since our analysis

CTiphasized the use of 'Vorst case" sign designs, seven words

(>iiller, 1956) were used as an upper limit.

For "worst case" design purposes, it is important to assume th^t

drivers -islll be traveling in the leftmost lane ^shen passing the sign. Since

rural settings where directional signs are allowed are unlikely to be

carr>"ing dense traffic, only three lanes vrere assum.ed.

Other factors which affect sign legibility include contrast bet^veen

the figure and ground (characters and their inmediate surround) , driver

reading habits and search strateg)', color and luminance of the sign,

atmospheric conditions, and windshield characteristics such as tinting

and dirt. These factors were not considered in the analysis.

Each model was used to determine the minimum line-of-sight distance

(vie^slng distance from the driver to the sign) at which reading must

start. The distance at which characters on each sign would be legible

13
(a function of visual acuity) can be compared with the minimum line-of- sight

distance to determine a sign's adequacy. If the legibility distance is

larger than the minimum viewing distance, characters would be legible

at the latter distance. If the legibility distance is smaller, the

characters would not be adequate at the minimum distance required by the

models.

After the minimum viewing distance was determined, the optimum ratio

of length to height was used to determine the dimensions of a sign which

would satisfy the Rule of Thumb legibility requirements at that distance.

These dimensions were obtained as follows:

Required Viewing distance

Sign = (from model) x lines of text and spacings

Height 50 ft/in (6 m/om)

Both models use the schematic diagram shown in Figure 3 . The parameters

are:

AB = minimum viewing distance.

AC = distance travelled while reading the sign.

DE = width of roadway (three lanes of traffic)

.

EF = perpendicular distance from the inner edge of the sign to the

outer edge of the roadway (lateral displacement)

.

FB = one half the sign width (length)

.

e (theta) = maximum acceptable angle, which determines the last point

where the driver can read the sign (terminal divergence

angle)

.

The equations for both models reduce to the following form:

AB = + (DE + EF + FB) cot 9]^ + (DE + EF + FB)

^

The models differ mainly in terms of the assumptions basic to each.

In practice, the essential differences are, (1) the amount of time assumed

necessary to read the sign, and (2) the terminal angle of regard. King

recommends an angle of 10° or less, while Rockwell recommends 30°.

King's discussion of sign size and location is presented as guideline information of use to highway engineers designing legible

signs for drivers who are reading such signs while monitoring road

traffic in the periphery of their visual field. For this reason, a

10° divergence angle is recommended. Rockwell, instead, presents his

model as a description of driver behavior actually observed, and

concludes that 30° is the angle at which most drivers stop looking at

the sign. In a similar view, King assumes a reasonable reading time

based on published research, whereas Rockwell concludes with a longer

assimied reading time since observed drivers did not look at the sign

during the entire period when it was legible to them.

14
A C D

Figure 3. Schemtic diagram of sign location used

for King's Dodel and Pvoclacell ' s nodel.

IS
Both models can be used for any combination of speed, lateral

displacement, sign width, number of words, and terminal divergence angle,*

but only the limited number of discrete points described in the previous

sections were used in this analysis. The values used were based on

"real world" values which closely match situations likely to be

encountered in the field.

2.5 Application of Models to Hypothetical Signs

To evaluate the hypothetical signs, answers were sought to these

questions

:

1. At 80, 60, 55, and 40 miles per hour (128.7, 96.6, 88.5, and 64.4

kilometers per hour) , what is the maximum viewing distance at

which Standards -conforming signs should be legible?

2. What effect does the lateral displacement from the road have

upon the viewing distance?

3. For four-line signs, what is the minimum height, length, and area which would meet the driver's needs, if 50 ft/in (6 m/om) is the

visual acuity used? Only four-line signs were used because they

made full use of the available area.

3.0 Results

The Standards address five factors related to sign design and placonent.

These are: (1) maximum sign area of 150 ft (13.9 m ) , (2) length and height

each restricted to a maximum of 20 ft (6.1 m) , (3) no more than three signs per

route, (4) spacing between signs must be at least one mile (1.6 km) ^ and

(5) maximum distance from signs to the site is 50 or 75 air miles (80.5 or

120.7 km), depending on the type of road system.

3.1 Problon Areas in the Standards

A review of the Standards and official records showed minimal reference

to supporting technical data. For example, no source could be identified to

support the one mile (1.6 kilometer) spacing between signs, or the restriction

of height and length to 20 ft (6.1 m)

.

A supplementary report from the Commission on Highway Beautification

(1975, draft) noted that the 660 ft (201.2 m) setback limit was apparently

a legislative compromise. In 1955, the Congress had recommended 550 ft

(167.6 m) in similar highway legislation and later hearings before the

Department of Commerce were concluded with a 750 ft (228.6 m) reccmmendation.

The present setback of 660 ft (201.2 m) is one-eighth of a mile, a furlong,

and is apparently not based on highway construction requirements or driver

constraints . -

*If tne terminal angle of regard exceeds 90° , then the driver will be beyond

the sign and must look back at it to finish reading, an impossible situation.

Past 90° only the back of the sign is visible if the plane of the sign is

perpendicular to the roadway.

16
Similarly, the 150 ft (13.9 m ) maximuQ area was adopted over 15 years

ago. Its basis is uiiknoim. In a field surx^ey of signs erected next to

highways throughout the countr>' (excluding right -of-ray signs) , FHl\"A

ascertained that over 75% were 150 ft^ (13.9 ""r-; or less. Such face

A'alidity ^.-as apparently used as the basis for continuing the restriction.

As summarized in Appendix B, state standards for directional signs

submitted to FHl\A for reviev; are essentially in conformance ivlth the Federal

regulations. Minor modifications were made on many points, but in terms

of sign dimensions and number, all comply >,lth the 131(c) requirements.

3.2 Consultant Conclusions

There was general agreanent among the consultants, but i\lth differences

of opinion expressed about the specifics of several restrictions. Each

consultant stated that a maximum sign size of 150 ft^ (13.9 m^) ras probably

too restrictive for all signing situations, and that many factors affect

the minimum necessarv' sign area (e.g., lateral displacem.ent from the

roadway, message length, surrounding terrain and traffic density)

.

Similar obsen'ations were made concerning character size. The consultants

suggested that parameters traditionally used to determine the minimum

character size needed for right-of-way signs could just as well be applied

to 131 Qc) t}T€ signs, so as to tailor each to the requirements Imposed

by its intended location. Parameters noted \\eTe: visual angle subtended

by the image, angle of regard, and traffic density.

No direct cceiments vrere received vdth respect to the number of signs per

route. The most direct statement on this point ras the suggestion that the

"rule of three" concept used in right-of-i\"ay highray signing should also be

applied to the 131(c) ty^e of signs. This concept requires that three

separate ramings be given to drivers prior to each decision point. The

one mile (1.6 >rj spacing was considered to be well above the minimum needed

to avoid confusion and distraction. Suggestions were m^ade that if a more

different limit is ever adopted it should never be less than 1500 to 2000 ft

(45,7.2 tc 603.6 m) . One expert also suggested that more than one attraction

could be announced at the same sign location, particularly when placed

immediately prior to a decision point . Xo direct comm.ents were r^ade nor any

data cited xvlth regard to the distance from the signs to the site.

3.3 Field Site Measurements

Four signs erected in compliance v.lth the Standards vrere measured to

ser\'e as a frame of reference when analyzing the h>'pothetical signs. Although

selected signs did not constitute a statistically representative sample,

they did sen^e as examples of field problons and practices

.

The physical measuronents of the signs are presented in Table 1 . They

include the height and length of the sign board; height, \%ldth and stroke

vddth of selected characters; and the lateral displaconent of the sign.

Sign length and the number of words in each sign vrere used v.lth King's model

to determine the maximum viev.lng distance at v.hich each of these signs should

17
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be legible, at several velocities and lateral displacements. These data are presented in Table 2. Also shoMi in this table is the maximum distance at

which the sign characters would be legible, based on 50 ft (15.2 m) of viewing

distance for every inch (2.54 am) of character height. Signs C and D are

not legible at the distance required by King's model, which means that the

divergence angle would be greater than 10° before reading was completed.

A variety of signing techniques are shorn in Appendix C. Only caverns

related signs were photographed and measured, since other-types of sites in

the Washingtion, D.C. area have not yet erected signs under the Standards.

Unless located in commercial zones , non-conforming signs for all types of

sites are scheduled to be removed by December 1976.

3.4 Sign Size, Legibility, and Theoretical Models

2 2

For the hypothetical signs, the 150 ft (12.9 m ) limitation was the

binding constraint for the four-line format. The two- and three-line

formats were constrained by the maximum 20 ft (6.1 m) length allowed.

Figure 4 presents the percentage of available area used by each Standards

conforming sign (as reported in Table 3) . Table 4 presents the distances

at v/hich the fictitious message would be legible on Standards -conforming

signs, for four levels of visual acuity.

The distance at which the signs should be legible was determined for

each sign using both King's model and Rockwell's model. For each of the

four-line signs the five different configurations did not produce

substantial differences to such distances. For this reason, the data for

only one sign, (configuration D of the four-line signs) are presented in

tabular form (Table 5)

.

Table 6 presents the minimum viewing distances for all two- and threeline signs (each of which was restricted in length to 20 ft (6.1 m) . Since

theoretically derived viewing distances are based on sign length, such

distances for these signs are identical.

The height, length, and area which would be required at the various speeds

and placement distances were calculated only for four-line signs because

such signs allowed the largest character size within the constraints. The same procedures can be used to calculate these dimensions for any other sign.

Figures 5 and 6 illustrate the minimum viewing distance required by the

models under several conditions , and the maximum distance at which characters

of the hypothetical signs would be legible.

If all of Rockwell's assumptions are accepted, the Standards are not

adequate for drivers having normal (20/20) visual acuity, traveling at

speeds above 60 mph (96.6 kph) . King's model assumes less reading time required,

but many of the test signs placed 80 ft or less from the pavement are also

not adequate at speeds above 60 mph (96.6 kph). Although it is unlikely

that anyone would choose to erect a sign at the limits of the protected zone

(660 ft or 201.2 m beyond the right of way) if a closer position were

available, the size of such a sign at that distance would have to be several

thousand square feet to be legible, far exceeding the 150 ft^ (15.9 m^) limit.

Tables 7-9 present sign dimensions needed to display legible messages on the

UC/LC, 0.75 spacing, four-line sign at various speeds, lateral displacements

and divergence angles

.

20
Table 3

Dimensions of "optimum" signs. (Area figures are rounded to the nearest whole ft2.)

Configuration A

Configuration B

Configuration C

Configuration D

Configuration E

All UC characters, 0.75 spacing.

All UC, 0.75 spacing, destination 1.5

times as large.

All UC, 0.33 spacing.

UC/LC, 0.75 spacing.

UC/LC, 0.75 spacing, destination 1.5

times as large.

Four-line Signs

A

B

Three -line Signs

A

B

C

Two -line Signs

A

Height

8.77 ft

2. 67 m

8.24 ft

2.51 m

8.02 ft

2.44 m

8.78 ft

2.65 m

8.24 ft

2. 67 m

5.15 ft

1.56 m

4.36 ft

1.Z2 m

4.43 ft

1.35 m

5.23 ft

1.59 m

4.44 ft

1.25 m

3.65 ft

1.11 m

3.36 ft

1.02 m

3.28 ft

0. 99 m

3.70 ft

1.16 m

3.42 ft

1.04 m

Length

17.09 ft

5. 20 m

18.19 ft

5.54 m

18.68 ft

5. 69 m

17.08 ft

5.20 m

18.18 ft

5.54 m

20.00 ft

6.09 m

20.00 ft

6. 09 m

20.00 ft

6. 09 m

20.00 ft

6. 09 m

20.00 ft

6. 09 m

20.00 ft

6. 09 m

20.00 ft

6.09 m

20.00 ft

6. 09 m

20.00 ft

6.09 m

20.00 ft

6. 09 m

21

Area

150 ft , 13. 9 m" 150 ft^ , 13. 9 m' 150 ft^ , 13. 9

150 ft^ , 13. 9 m' 150 ft^

13.9 m

103 ft^,

9. 6 m" 87 ft^,

8.1 m" 89 ft^,

8.2 m" 105 ft^

9.8 m

89 ft^

8.3

73 ft%

6.8 m

67 ft^

6.2 m

66 ft^

6.1 rn 74 ft^

6. 9 m

68 ft^2

6.3 m

2

Percentage of

available area used

1001

100%

100%

100%

100%

69%

58%

59%

70%

60%

49%

45%

44%

49%

45%
All UC, 0.75 spacing.

All UC, 0.75 spacing,

destination 1.5 times as large.

o

If)

rH•H1

O

CDW)

o

5h

01

100^

90%

80°^

70%

60 6 *

50^

40^

301

All UC, 0.33 spacing.

iTrj UC/LC, 0.75 spacing.

UC/LC, 0.75 spacing,

destination 1.5 times as large.

Four -line Signs Three -line Signs Two-line Signs

Figure 4. Percentage of available area used by Standards -conforming;

hypothetical signs. (From Table 3.)

22
Table 4

Distances in feet at which the hypothetical "Standards-conforming"

signs TOuld be legible, at various levels of visual acuity.

(Distances in meters are shown in italics.) Sign configurations A-E

are the same as those presented in Table 3.

Four -line Signs

Visual

Acuity A B C D E

20/20 669 713 731 774 824

20S.9 217.3 222.8 235.9 251.2

20/23 584 662 638 677 719

178.0 189.6 194.5 206.3 219.2

20/40 338 360 369 391 416

103.0 109.7 112.5 119.2 126.8

20/70 191 204 209 221 235

58.2 62.2 63.7 67.4 71.6

Three- line Signs

Visual

Acuity A B C D E

20/20 508 507 508 596 596

154.8 154.5 154.8 181.7 181.7

20/23 443 442 443 521 521

135.0 134.7 135.0 158.8 158.8

20/40 256 256 257 301 301

78.0 78.0 78.3 91.7 91.7

20/70 145 145 145 170 171

44.2 44.2 44.2 51.8 52.1

Two -line Signs

Visual

Acuity A B C D E

20/20 508 507 507 595 597

154.8 154.5 -154.5 181.4 182.0

20/23 443 442 442 520 521

135.0 134.7 134.7 158.5 158.8

20/40 257 256 256 300 302

78.3 78.0 78.0 91.4 92.0

20/70 145 145 145 170 171

44.2 44.2 44.2 51.8 52.1

23
Table 5 Viewing distances in feet from which a four- line, UC/LC sign having

0.75 interline spacing should be legible, according to two models (King,

1971; Rockwell, 1973). Model-derived distances are shown for various

vehicular speeds, lateral displacements, and divergence angles.

(Distances in meters are shown in italics.)

10° Divergence Angle

Lateral Displacement 5 ft 35 ft 80 ft 740 ft

80 mph King 742 (226) 914 (279) 1172 (357) 4970 (1515)

(128.7 kph) Rockwell 1245 (279) 1416 (432) 1 674 ( 51 0) 5468 (1667

60 mph King 622 (190) 794 (242) 1052 (321) 4851 (1479)

(96.6 kph) Rockwell QQQ 1 O Wd: J 1170 (357) \. '±00 J 5224 (1592)

55 mph King 592 (180) 764 (233) 1022 (312) 4822 (1470)

(88.5 kph) Rockwell / \ 600 J 1109 (338) XoDD { '±1 OJ 5163 (1574)

40 mph King 501 (153) 674 (205) 933 (284) 4732 (1442)

(64.4 kph) Rockwell 7 ^^7 f 99 Q) \ 0 CiV J 924 (282) XXO <i 4981 (1518)

30° Divergence Angle

Lateral Displacement 5 ft 35 ft 80 ft 740 ft

80 mph King 563 (172) 618 (188) 702 (214) 1993 (607)

(128.7 kph) Rockwell J- uuo \ 0 0 0 y 1119 (341) [ 0 u u / 2464 (751)

60 mph King 443 (135) 498 (152) 583 (178) 1883 (574)

(96.6 kph) Rockwell OX y ( U J 873 (266) f 9Q1 ) 2232 (680)

55 mph King 413 (126) 468 (143) 554 (169) 1856 (566)

(88.5 kph) Rockwell 7 c;r

/ JO /' 9 ? 7 1 812 (247) ( 97 9 ) 2174 (663)

40 mph King 323 ( 98) 380 (116) 466 (142) 1774 (541)

(64.4 kph) Rockwell { 1 f 0 J 628 (191) 71/ X 7z, (917) 2003 (611)

40° Divergence Angle

Lateral Displacement 5 ft 35 ft 80 ft 740 ft

80 mph King 538 (164) 577 (176) 637 (194) 1614 (492)

(128.7 kph) Rockwell 1041 (317) 1078 (329) 1136 (346) 2069 (631)

60 mph King 418 (127) 458 (140) 520 (158) 1510 (460)

(96.6 kph) Rockwell 795 (242) 833 (254) 891 (272) 1843 (562)

55 mph King 388 (118) 428 (130) 490 (149) 1484 (452)

(88.5 kph) Rockwell 733 (223) 771 (235) 830 (253) 1787 (545)

40 mph King 299 ( 91) 340 (104) 403 (123) 1408 (429)

(64.4 kph) Rockwell 549 (167) 588 (179) 648 (198) 1623 (495)

24
Table 6

Viewing distances in feet from which t\so and three- line signs should

be legible, according to t\\'o models (King, 1971; Roctov"ell, 1973).

Model-derived distances are sho^m for various vehicular speeds,

lateral displacements, and divergence angles. [Distance in meters

shown in italics.)

10° Divergence ."vngle

Lateral Displacement 5 ft 35 ft 80 ft 740 ft

80 mph

(128.7 kph)

King

Rockvvell

750

1253

(299)

(382)

922

1424

(281)

(434)

1180

1682

(360)

(513)

4979

5476

(1518)

(1669)

60 mph

(96.6 kph)

King

Rocbcell

630

1007

(192)

(307)

802

1178

(244)

(359)

1061

1436

(323)

(438)

4860

5233

(1481)

(1595)

55 mph

(88.5 kph)

King

Roda^-ell

600

945

(183)

(288)

111

1117

(235)

(340)

1031

13"5

(314)

(419)

4830

5172

(1472)

(1576)

40 mph

64.4 ]q)h)

King

Rocbvell

510

761

(155)

(232)

682

933

(208)

(284)

941

1191

(287)

(363)

4741

4989

(1445)

(1521)

30° Divergence -Angle

Lateral Displacement 5 ft 35 ft 80 ft 740 ft

80 mph King 566 (172) 620 (189) 704 (215) 1996 (608)

(128.7 kph) Rockwell 1068 (326) 1122 (342) 1203 (367) 2467 (752)

60 mph King 446 (136) 501 (153) 586 (179) 1886 (575)

(96.6 kph) Rocfavell 822 (251) 876 (267) 958 (292) 2235 (681)

55 mph King 416 (127) 471 (144) 556 (170) 1858 (566)

(88.5 kph) Rocbvell 760 (232) 815 (248) 897 (273) 21"" (664)

40 mph King 326 ( 99) 382 (117) 469 (143) 1777 (542)

(64.4 kph) Rockwell 576 (176) 631 (192) 715 (218) 2006 (611)

40° Divergence .Angle

Lateral Displacement 5 ft 35 ft 80 ft 740 ft

80 mph King 540 (165) 5-9 (177) 639 (195) 1616 (493)

(128.7 kph) Rocbvell 1043 (318) 1080 (329) 1138 (347) 20^1 (631)

60 mph King 420 (128) 460 (140) 522 (159) 1512 (461)

(96.6 kph) Rocbv'ell 797 (243) 835 (254) 893 (272) 1845 (562)

55 mph King 390 (119) 430 (131) 492 (150) 1486 (453)

(88.5 kph) Rockwell 735 (224) ITS (236) 832 (254) 1789 (545)

40 mph King 301 ( 92) 342 (104) 405 (124) 1410 (430)

(64.4 kph) Rocb\"ell 551 (168) 590 (180) 650 (198) 1625 (495)

25
80 mph (128.7 kph)

T3

Id

CD

(UO

c

•HI

•H>

1600

r4S7. 7)

1400

(426. 7)

1200

(365.8)

1000

(304.8)

800

(243.8)

600

(182.9)

400

(121.9)

55 mph (88.5 kph).

40 mph (64.4 kph)

\ 80 mph (128.7 kph)

^ 55 mph (88.5 kph)

40 mph (64.4 kph)

Rockwell

^- - ^ King

25 50

(15.2)

75

I 100

(30.5)

Lateral displacement from pavement edge to sign edge (ft, m)

Figure 5. Viewing distance needed to read characters on a four-line sign,

UC/LC characters, 0.75 interline spacing, at a 10° divergence

- angle at various lateral displacements. The horizontal dotted

line is the distance at which the characters on the four -line

sign would be legible to stationary viewers of 20/20 visual acuity.

(From Table 5.)

26
1600 . (487. 7)

1400

(426. 7)

1200

(365.8)

CDC

oj (304.8) u

+->

80 mph ri2S. 7 fep^zj

1000

800 , (242.8)

600

400

(121.9)

55 mph rS5.5 ^^p/^J

40 mph (64.4 kph)

80 mph (128.7 kph)

55 mph (88.5 kph)

40 mph rff4.4 kph)

Rockwell ^ King

IT 50 75

(7.6) (15.2)

Lateral displacement from pavement edge to sign edge (ft, m)

Figure 6. Viewing distance needed to read characters on a four-line sign,

UC/LC characters, 0.75 interline spacing, at a 30° divergence

angle at various lateral displacements. The horizontal dotted

line is the distance at which the characters on the four- line

sign would be legible to stationary viewers of 20/20 visual acuity.

(From Table 5.)

27
Table 7

Sign dimensions in feet needed to display the four- line, UC/LC, 0.75

interline spacing sign to drivers of 20/23 visual acuity, at a 10°

divergence angle, at various vehicular speeds and lateral displacements.

(Dimensions in meters are shown in italics.)

10° Divergence Angle

Lateral Displacement 5 ft 35 ft 80 ft 740 ft

Height 9.58 ( 2.92) 11.80 ( 3.60) 15.14 ( 4.61) 64.20 ( 19.57) ^ ^ Length 18.64 ( 5.68) 22.96 ( 7.00) 29.46 ( 8.98) 124.92 ( 38.08)

Area 179 (16.6 ) 271 (25.2 ) 446 (41.4 ) 8020 (745.0 ) CO

u O Q

Height 16.08 ( 4.90) 18.29 ( 5.57) 21. tl ( 6.59) 70.63 ( 21.53)

Length 31.29 ( 9.54) 35.59 (10.85) 42.07 (12.82) 137.43 ( 41.89)

Area 503 (46.7 ) 651 (60.5 ) 910 (84.5 ) 9707 (901.8 )

Height 8,,03 ( 2.45) 10..25 ( 3. 12) 13. 59 ( 4.14) 62.,66 ( 19.10)

Length 15,.62 ( 4.76) 19.,94 ( 6. 08) 26..44 ( 8.06) 121.,92 ( 37.16)

Area 125 (11.7 ) 204 (19. 0 ) 359 (33.4 ) 7640 (709.7 )

Height 12.,90 ( 3.93) 15..11 ( 4. 61) 18,.44 ( 5.62) 67..48 ( 20.57)

Length 25.,10 ( 7.65) 29..40 ( 8. 96) 35. 88 (10.94) 131.,30 ( 40.02)

Area 324 (30.1 ) 444 (41. 3 ) 662 (61.5 ) 8860 (823.1 ) vD O

Height 7..64 ( 2. 33) 9..86 ( 3. 01) 13..20 ( 4.02) 62..28 ( 18.98)

Length 14..87 ( 4. 53) 19..19 ( 5. 85) 25..68 ( 7.83) 121..18 ( 36.94)

Area 114 (10. 6 ) 189 (17. 6 ) 339 (31.5 ) 7547 (701.1 )

Height 12..10 ( 3. 69) 14..32 ( 4. 36) 17.,65 ( 5.38) 66.,69 ( 20.33)

Length 23..54 ( 7. 17) 27..86 ( 8. 49) 34.,34 (10.47) 129..77 ( 39.55)

Area 285 (26. 5 ) 399 (37. 1 ) 606 (56.3 ) 8654 (804.0 ) LO O

bp

•H

to

rC rH o u

Pi

Height 6..48 ( 1. 98) 8..70 ( 2. 65) 12..04 ( 3.67) 61..13 ( 18.63)

Length 12..61 ( 3. 84) 16..93 ( 5. 16) 23..43 ( 7.14) 118..95 ( 36.26)

Area 82 ( 7. 6 ) 147 (13. 7 ) 282 (26.2 ) 7271 (675.5 )

Height 9..72 ( 2. 96) 11.,94 ( 3. 64) 15..27 ( 4.65) 64..33 ( 19.61)

Length 18..91 ( 5. 76) 23..23 ( 7. 08) 29..71 ( 9.06) 125..17 ( 38.15)

Area 184 (17. 1 ) 277 (25. 8 ) 454 (42.2 ) 8052 (748.1 )

28
Table 8

Sign dimensions in feet needed to display the four-line, UC/LC, 0.75

interline spacing sign to drivers o£ 20/23 A'isual acuit>^, at a 30°

divergence angle, at various vehicular speeds and lateral displacements.

(Dimensions in meters are shorn in italics.)

eral Displacanent 5 ft

Height

Length

Area

7.27

14.15

103

( 2.22)

( 4.31)

( 9.6 )

30° DiA'ergence Angle

ft 80 ft

7.98 ( 2.43)

15.53 r 4.73)

124 (11.5 )

9.06 ( 2.76)

17.63 ( 5.37)

160 (14.8 )

7AO ft

25.75

50.10

1290

( 7.85)

( 15.27)

(119.9 )

II Height

I Length

"5 Area

13.

26.

368

( 4.19)

( 8.16)

(34.2 )

14.45

28.12

406

r 4.40) 15.51 ( 4.73) 31.83 ( 9.70)

( 8.57) 30.18 r 9.20) 61.94 ( 18.88)

(37.8 ) 468 (43.5 ) 1972 (183.2 )

Area

5.72

11.13

64

( 1.74)

( 3.39)

( 5.9 )

6.44

12.53

81

r 1.96)

( 3.82)

( 7.5 )

7.53

14.65

110

( 2.30)

( 4.47)

(10.3 )

lA.Zl

47.32

1151

( 7.41)

( 14.42)

(lOi )

.Area

10.58 ( 3.22) 11.28 ( 3.44)

20.59 ( 6.28) 21.95 ( 6.69)

218 (20.2 ) 248 (23.0 )

12.34 ( 3.76)

24.01 ( 7.32)

296 (27.6 )

28.83

56.10

1617

( 8. 79)

( 17.10)

(150.3 )

Height

=" Length

'2 .Area

0 . J)0 10.3"

55

( 1.62)

( 3.16)

( 5.1 )

6.05

11.77

71

84)

.59)

.6 )

7.15

13.91

99

r 2.18)

( 4.24)

( 9.2 )

23.97

46.64

1118

( 7. SI)

( 14.22)

(103.9 )

- Height 9.79 ( 2.98) 10.49

% ler.rth 19.05 ( 5.81) 20. Al

Z --rea 187 (17.3 ) 214

( i ( i (11

20)

22)

9 )

11.55

22.47

260

( 5.52)

( 6.85)

(24.1 )

28.09

54.66

1535

( 8. 56)

( 16.66)

(142.6 )

Iht 4.17 ( 1.27) 4.90

:th 8.11 ( 2.47) 9.53

= 34 ( 3.1 ) \-

49)

90)

.3 )

6.02

11.71

70

83)

57)

6 )

22.91

44.58

1021

r 6. 98)

( 13.59)

( 94.9 )

- Height 7.41 ( 2.26) 8.11 ( 2.47) 9.19 ( 2.80) 25.87 ( 7.89)

2 Length 14.42 ( 4.40) 15.78 ( 4.81) 1".88 ( 5.45) 50.34 ( 15.34)

Z .Area 107 ( 9.9 ) 128 (11.9 ) 164 (15.3 ) 1302 (121.0 )

29
Table 9

Sign dimensions in feet needed to display the four- line, UC/LC, 0.75

interline spacing sign to drivers of 20/23 visual acuity, at a 40°

divergence angle, at various vehicular speeds and lateral displacements.

(Dimensions in meters are shown in italics.)

40° Divergence Angle

Lateral Displacement 5 ft 35 ft 80 ft 740 ft

5 Height 6.95 ( 2.12) 7.46 ( 2.27) 8.23 ( 2.51) 20.84 ( 6.36) ^ Length 13.52 (4.12) 14.52 (4.43) 16.01 (4.88) 40.57 (12.37)

i3 Area 94 ( 8.7 ) 108 (10.1 ) 132 (12.2 ) 846 ( 78.6 )

<^0 Height 13.44 ( 4.10) 13.93 ( 4.25) 14.67 ( 4.47) 26.72 ( 8.14)

p. P Length 26.15 ( 7.97) 27.11 ( 8.26) 28.54 ( 8.70) 51.99 ( 15.85) ^ u Area 351 (32.7 ) 378 (35.1 ) 419 (38.9 ) 1389 (129.1 ) o o

00 PC

S Height 5.41 ( 1.65) 5.92 ( 1.80) 6.71 ( 2.05) 19.50 ( 5.94) ^ Length 10.53 (3.21) 11.52 (3.51) 13.06 (3.98) 37.94 (11.56) ^ Area 57 ( 5.3 ) 68 ( 6.3 ) 88 ( 8.1 ) 740 f 55. 7 j

to

H Height 10.27 r 3.13) 10.76 r 11.51 ( 3.51) 23.81 T 7.25;

% % Length 19.98 r 6.09) 20.94 r 5.38; 22.40 ( 6.83) 46.33 C 24.12;

o -u Area 205 (19.1 ) 225 (20.9 ) 258 (24.0 ) 1103 n^?2.5 ; vO o

S Height 5.02 ( 1.53) 5.53 r 1.69) 6.33 C 2.5S; 19.17 ( 5.84) ^ c Length 9.77 ( 2.98) 10.76 f 3.28) 12.32 T 5.75; 37.30 ( 11.37)

Area 49 ( 4.6 ) 60 r 5.5 ; 78 r 7.2 ; 715 ( 66.4 )

Height 9.47 r 2.S5; 9.96 ( 3.04) 10.72 r 3.27) 23.09 T 7.0^;

% Length 18.43 T 5.52; 19.38 ( 5.91) 20.86 r 6.36) 44.93 T JS.59; o Area 175 ^5.2 j 193 (17.9 ) 224 r20.S ; 1037 ( 96.4 ) LO O

3 Height 3.86 r 1.18) 4.39 f J. 24; 5.21 ( 1.59) 18.18 r 5.54; ^ C Length 7.51 r 2.29) 8.54 r 2.50; 10.14 ( 3.09) 35.37 T 20.75;

Area 29 r 2. 7 ; 37 ( 3.5 ) 53 r 4.9 ; 643 r 55. 7

;

Height 7.09 T 2.16) 7.59 T 2.22; 8.37 ( 2.55) 20.97 T 5.29;

% % Length 13.80 T 4.21) 14.77 T 4.50; 16.29 ( 4.97) 40.80 r 22.44;

o Area 98 ( 9.1 ) 112 r20.4 ; 136 (12.7 ) 856 ( 79.5 ) u

Pi

30
For all practical purposes , eye movement (without head m.ovQnent) is

not expected of drivers past the center o£ their rear vieiv mirror. \\Tiile

this angle is dependent upon many factors, 40° is a reasonable average.

Using a terminal divergence angle of 40° for King's model, most Standards

conforming signs could be read at most speeds - unless located far from

the edge of the right-of-way.

4.0 Discussion

4 . 1 Problem Areas

Available records did not explain the rationale for adopting the

current limits in the Standards, and state codes do not differ significantly

from the provisions spelled out in the 131 (c) regulations. Thus, it was

necessary- to consider the specific objections raised by the National Caves

Association (NCA.) and other potential problems raised by research results to

evaluate the adequacy of the Standards.

NCA objections to the Standards were primarily concerned \\ith the size

and number of signs allowed. In place of existing restrictions, a 700%

increase in total area (doubling the number of signs allowed and increasing

the area of each to 600 ft^ (55.7 m^)) was proposed. Rather than react

directly to these proposed changes, the approach taken in this project was

to objectively determine sign dimensions adequate for the field environment

expected. Aspects of the Standards considered potential problems and

subject to examination T\"ere sign dimensions, spacing between signs, and

the number of signs allowed per route.

4.2 Development of Theoretical Tests

Since official records did not explain the rationale used to select

the values for these variables, and since the available literature did not

directly address the specific points in the Standards , it was necessary to use design paradigms originally developed for right-of-way signs to

evaluate our h}'pothetical , 'Vorst case" examples.

Figure 4 illustrates the in^ortance of properly arranging messages to

make best use of the available area, i.e., a four-line Standards -conforming

sign constrained only by an area limit, would be legible at the required

\de'\\lng distance, though t\-JO- and three-line versions of the same message

would he of inadequate character height since they were constrained more

sever ly by the length limit. So long as maximum limits on height and length

are in the Standards, their influence is greatly affected by the sign format

used.

Addressing a separate issue. Tables 5 and 6 present data which can be

used to judge the adequacy of signs conforming to the existing dimensional

restrictions. Listed in these tables are the sign dimensions needed to display

the Schmillingrass Caverns message at the model -derived viewing distances,

to drivers of 20/23 visual acuity.

As sho^NTi in Tables 7-9, for many conditions signs must be larger than

150 ff^ (13.9 m^) to meet the requirements of each model. As speed and

lateral displacement increase, Standards -conforming signs become more and

31
more inadequate. However, i£ signs are located 35-80 ft (10.7-24.4 m) from

the pavement and the angle of regard is assumed to be 30°, many Standards

conforming signs are adequate. For example, at the minimum speed (40 mph,

64.4 kph) , the minimum lateral displacement (5 ft. 1.5 m) . and at the largest

divergence angle (40°), a sign of less than 30 ft^ (2.8 m^) would be

adequate to meet King's assumptions, and a sign of 98 ft^ (9.1 m^') would

meet Rockwell's assumptions. However, at 80 mph (128.7 kph) , 740 ft (225.6 m)

fran the edge of the pavanent, and using a 10° divergence angle, the same j sign would have to be several thousand square feet.

Specific values must be assumed for the essential parameters of ' speed, lateral displacement, divergence angle, and visual acuity if the

data from these tables are to be used to determine in what way and to

what extent the standards are adequate or inadequate.

The sign size required at the outerm.ost edge of the protected zone is

far in excess of 150 ft (12.9 m ). Few businesses would be likely to choose

such a distant placanent if a closer position were available, but it can be

concluded that signs of 150 ft^ (12.9 m^) are not adequate at all points

within the protected zone. If the size restriction is to be maintained, a shorter, maximum setback distance within the protected zone should be

adopted, or a range of sizes be defined for various lateral displacements.

The data illustrate the importance of visual angle in sign design.

Signs which meet the optimum length/height ratio increase in area as they

are placed farther from the roadway. The effect is comparable to projecting

an image on a screen. When close, the image is small, and it increases in

size as the screen is moved farther away. Though the actual size of the

image on the screen changes, the visual angle which that image subtends at

the viewer's eye is constant. If the Standards placed a restriction on

the size of the visual angle which the sign could subtend, signs placed at

all distances from the roadway would all present the same image size to a viewer. As an alternative to an absolute size regulation, a maximum visual

angle specification wuld seem to be consistent with intent of the 150 ft^

(12.9 rrr) restriction currently in the Standards.

To insure that the text on each sign is legible (a need not directly

addressed in the current Standards) , the visual angle which the stroke

width of characters must subtend should also be specified. If this change

was coupled to a maximum visual angle for the sign itself, signs would be

of uniform impact because their images would be of a constant apparent

size, and the individual characters would be legible.

4.3 Limitations of the Models

These paradigms were selected and used because they presented

illustrative examples of the parameters which must be considered in

evaluating the Standards. As previously described, the essential

differences between the models are the reading times assumed and the

maximum divergence angles recommended. Both models were originally

developed primarily for right-of-way signs; as the lateral displacement

becomes large the models are not entirely adequate because the orientation

32
of the sign itself becomes a major factor. It must be emphasized that

no models were located which specifically addressed the highway signing

situations covered by the Standards, and to that extent the viewing

distances, character sizes, and sign dimensions could be expected to

change if a more appropriate model were used instead.

4.4 Conclusions and Recommendations

Some parts of the Standards should be modified, to better meet the

needs of drivers in the variety of field situations likely to be

encountered when reading signs.

1. Directional sign Standards should require individual characters

to be legible at the minimum visual acuity levels specified in state driver

licensing regulations. For ease of use by highway engineers, this can be

specified as a ratio of viewing distance/character height. The proper

ratio would depend on the stroke width of the type of characters used.

2. Restricting the physical dimensions of signs may constrain those

sites seeking to display long -named items of information. Instead,

restrictions should limit the visual angle subtended by the sign

in the horizontal and vertical directions. This would mean that signs

placed close to the road would be smaller than those placed further

away, that both would be of the same apparent size to the viewer, and

that justifications for large signs would be based only on legibility

needs of drivers.

3. No material was located to support a change to the present

proximity limits between directional signs and interchanges or exits ; to

the number of signs allowed, or to the maximum distance from sign location

to site location.

4. In terms of motorists' needs, the one mile (1.6 hn) spacing

between signs is adequate. Consultants recommended no change, but

cautioned that this distance never be reduced to less than 1500-2000 ft

C4 57. 2- 6 09. 6 ml.

In the process of studying deficiencies and improvements to the

Standards, the consultants made several other observations \riiich merit

consideration.

1. The current Standards include no "break away" requirements. In

the interest of safety, signs covered by 131(c) regulations and located

less than 80 ft C24.4 ml from the pavement should also comply with the

break away requirements imposed on right-of-way signs.

Z. Many developed cavern sites are located in close proximity to one another, due to the geological make-up of the area and ease of access

for tourists. Motorists would be aided if right-of-way signs were used

to announce the type of activity accessible from an exit (see Figures 21

and 22)

.

33
3. Effective, attention-getting signs of reasonable size are possible if standard shapes or colors are used. However, their use

would require public education - more than a minor problem.

4. Consultants suggested that perhaps a priority of sign placement,

indpendent of right-of-way, should be adopted. With this system of

priorities, drivers could search specific areas of the visual field for

driving information signs, without constantly scanning for signs over the

entire area in front of the vehicle. For example, information signs

could be located 35-50 ft (10.7-15.2 m) into the right-of-way, or overhead, and caverns-type directional signs could be located in the same position or at some other standard distance, such as 80 ft (24.4 m)

.

4.5 Recommended Research

As noted several times in this report, most of the literature reviewed

for this project was not directly applicable to the problems under study.

To remedy this situation, several areas of research should be pursued.

1. The legibility of signs erected outside the right-of-way has not

been sufficiently examined. More field testing is needed.

2. Laboratory experiments involving humans often yield data which

are inconsistent with field results. As an example, the Janesville field

study (National Advertising Company, undated report) determined that a

42 ft/ in (S.04 m/cm) legibility distance/character height ratio was necessary

for signs to be legible, whereas simulation studies had yielded a 50 ft/in

(6 m/cm) ratio. Had the simulation-derived figures been used without

field testing, all signs would have been too small for their intended

placanent. Field validation of laboratory studies and theoretical models

is essential.

3. More data are needed on drivers' visual abilities. The proper

ratio of viewing distance to character height is not firmly established,

and the maximum terminal divergence angle has not been identified. Not

only do they depend upon visual acuity and speed but also the familiarity

of the message to be perceived and the type of characters used. Much

work also needs to be done on the gestalt of highway sign perception - especially in terms of familiarity, driver attention and motivation, and

driver expectancies and stereotyped responses. The visual acuity

assumptions relate to such a gestalt , and could explain why words can

be read on a highway sign at longer distances than would be predicted

for a particular visual acuity level, even though some of the letters are

not clearly discerned.

4. Better data are needed to define the "actual" static and dynamic

visual acuity of the driving population. Many states require only a static

visual acuity examination, and then only at the time of initial license

application. Drivers whose vision has deteriorated over time may be

operating at levels far below the tested level.

5. Mach sign design is based upon assumed driver information needs.

Proper design requires a better understanding of such needs: What level

of information do drivers obtain prior to departure, what feedback is

expected along the way, and what details are assumed to be announced

prior to arrival? No research was identified by this project which

could define the specific information drivers require or when they require

it.

34
Selected References

Adler, B. and Straub, A.L. Legibility and brightness in sign design.

Paper presented to the annual conference of the Highway Research Board.

Washington, D.C., National Academy of Sciences and Highway Research

Board 1971.

Alexander, G.J. Report to Nfotorist Information Systems Coimnittee - Updating

Forbes ' , et a]^. 1964 Bibliography . Highway Research Board Committee

Correspon^nce, May 2, 1974.

Alexander, G.J., King, G.F. , Warskow, M.S., and MiGlamery, D. Development

of Information Requirements and Transmission Techniques for Highway Users . Texas Transportation Institute, July 1970.

Allen, T.M. Night legibility distance of highway signs, Highway Research

Board Bulletin , 1958, 191, 33-40.

Allen, T.M. , Dyer, F.N., Smith, G.M. , and Janson, M.H. Luminance

requirements for illuminated signs, Highway Research Record , 1967, 179 , 16-37.

Allen, T.M., and Straub, A.L. Sign brightness and legibility, Highway

Research Board Bulletin, 1955, 127, 1-22.

Allen, T.M. , Smith, G.M., Janson, M.H., and Dryer, F.N. Sign Brightness in

Relation to Legibility . Michigan Department of State Highways, August 1966.

Bhise, V.D. , and Rockivell, T.H. Toward the development of a methodology

for evaluating highway signs based on driver information aquisition.

Highway Research Record , 1973, 440, 38-56.

Bhise, V.D. , and Rockwell, T.H. Development of a Methodology for

Evaluating Road Signs . Project EES315B, Final Report, Ohio State University,

Columbus, 1973.

Bhise, V.D. , and Rockwell, T.H. Implementing Sign Research Results Into

Operational Practices . Project EES407, Final Report, Ohio State University,

Columbus, 1974.

Blood, D.M., Rajender, G.R. , Moncur, J., and Curie, E.J. Traveler Attitudes

Toward Highway Billboard Advertising: A Survey of Selected Wyoming Mot"eT

Patrons . Wyoming State Highway Department and Bureau of Public Roads

,

January 1969.

Bureau of Public Roads, Economic impact of the highway beautification

act. Volume 1, Staff Report, March 1967.

35
Burg, A. Vision and driving: a summary o£ research findings, Highway

Research Record , 1968, 216, 1-12.

Burg, A., and liilbert, S.F. Dynamic visual acuity as related to age, sex,

and static acuity. Journal of Applied Psychology , 1961, 45^(2), 111-116.

California Department of Motor Vehicles , The 1964 California Driver

Record Study . California Department of Motor Vehicles, Division of

Administration , Parts 1-8, December 1964 - March 1967.

Case, H.W., Michael, J.L., Mount, G.E., and Brenner, R. Analysis of

certain variables related to sign legibility. Highway Research Board , 1952, 60, 44-58.

Christie, A.W., and Hirst, G. Legibility of signs with green backgrounds.

Traffic Engineering ^ Control , March 1965, 6(11), 672-3.

Claus , K.E., and Claus, R.J. Visual Communication Through Sigiage , Volume 1, Perception of the Message . Cincinnati : Signs of the Times

Publishing Co. , 1974.

Commission on Highway Beautification, The Priority of Quality , Summary

Report, December 1973.

Commission on Highway Beautification, Supplemental Report to the Priority

of Quality . Draft version, 1975.

Connolly, P.L. Visual consideration: man, the vehicle and the highway,

Highway Research News , 1968, 30, 71-74.

Cunningham, P. A. Control of highway advertising signs, some legal

problems, Highway Research Board Report , 1971, 119 , 1-72.

Dewar, R.E. Psychological Factors in the Perception of Traffic Signs . Psychology Department, University of Calgary, February 1973.

Dunipace, D.W., Strong, J., and Huizinga, M. Prediction of nighttime

driving visibility from laboratory data. Applied Optics , 1974, 13(11)

,

2723-2734.

Elastic Nut Corporation of America, Spacing Rules and Regulations , Signal

Products Division, Elizabeth, New Jersey, 1962.

Ewald, W.R., Jr., and Mandelker, D.R. Street Graphics . The American Society

of Landscape Architects Foundation, Washington , D . C . , 1971.

Ferguson, W.S. Virginia Highway Signing. Phase I. Driver Awareness of

Sign Colors and Shapes . Virginia Highway Research Council and Bureau of

Public Roads, ^rch 1967.

36
Forbes, T.W. Methods o£ measuring judgment and perception time in passing

on the highway, HighvjRy Research Board Proceedings , 1939, 19^, 218-228.

Forbes, T.W. Factors of adequate sign design. Traffic Engineer's Handbook . Institute of Traffic Engineers, New York, 1941, 106-107.

Forbes, T.W. Factors in highway sign visibility. Illuminating Engineering , August 1970, 495-503.

Forbes, T.W. Human Factors in Highway Traffic Safety Research . New York:

Wiley- Interscience, 1972.

Forbes, T.W., Fry, J. P., Jr., Joyce, R.P., and Pain, R.F. Letter and sign

contrast, brightness, and size effects on visibility. Highway Research

Record, 1968, 216, 48-54.

Forbes, T.W. , Goldblatt, J., Greenwood, W.H., and Saari, B.B. A Study of

Characteristics of Highway Signs Optimal for Visibility and Legibility . (Preliminary Report) , presented at Seminar on Visual Signalling,

International Commission on Illumination, Washington, D.C. , April 1974.

Forbes, T.W. , and Holmes, R.S. Legibility distances of highway destination

signs in relation to letter height, letter width, and reflectorization.

Proceedings of the Higtovay Research Board , 1939, 19, 321-335.

Forbes, T.W. , Moscowitz, K., and Morgan, G. A comparison of lower case

and capital letters for highway signs , Proceedings of 13th Annual Meeting

of the Highway Research Board , December 1950.

Forbes, T.W. , Pain, R.F. , Bloomquist, D.W., and Vanosdall, F.E. Low contrast

and standard visual acuity under mesopic and phototopic illumination,

Journal of Safety Research , 1969, 1_, 5-12.

Forbes, T.W., Pain, R.F., Fry, J. P., and Joyce, R.P. Effect of sign position

and brightness on seeing simulated highway signs. Highway Research Record , 1967, 164, 29-37.

Forbes, T.W. , Pain, R.F., Joyce, R.P., and Fry, J. P., Jr. Color and

brightness factors in simulated and full-scale traffic sign visibility.

Highway Research Record , 1968, 216, 55-65.

Forbes, T.W. , Snyder, T.E., and Pain, R.F. Traffic Sign Requirements . Michigan State University, 1963, 15.

Forbes, T.W. , Snyder, T.E., and Pain, R.F. A Study of Traffic Sign

Requirements II . An Annotated Bibliograply^ College of Engineering

,

Michigan State University, East Lansing, Michigan, August 1964.

37
Forbes, T.W. , Snyder, T.F., and Pain, R.F. Traffic sign requirements I. Review of factors involved, previous studies and needed research,

Highway Research Record , 1965, 70_, 48-56.

Hall, W.A. , Walters, E.L., Nimeroff, I., and Douglas, C.A, Photometric

Tests of Vehicle Glazing I^-laterials . NBS Report 74-519, National Bureau

of Standards, Washington, D.C., August 1972.

Hanson, D.R. , and Woltman, H.L. Sign backgrounds and angular position.

Highway Research Record , 1967, 170, 82-96.

Hulbert, S.F. Evaluation of highway destination signs. Proceedings 7th

California Street ^ Highway Conference , University of California, Berkeley,

1955, 122-124.

Hulbert, S.F., and Burg, A. The effects of underlining on the readability

of liighway destination signs. Proceedings, Highway Research Board , 1957,

36, 561-574.

Hulbert, S.F., Burg, A., Knoll, H.A. , and Mathewson, J.H. A preliminary

study of dynamic visual acuity and the effects in motorist's vision,

Journal of the American Optometric Association , 1958, 29(6) , 359-364.

Hurd, F. Glance legibility, Traffic Engineering , 1946, 17, 161-162.

Institute of Outdoor Advertising, The First Medium , New York, 1974.

Kindersley, D. Motorway sign lettering, Traffic Engineering and Control

December 1960, 463-465.

King, B. , and Sutro, P. Dynamic visual fields. Highway Research Board

Bulletin, 1957, 152, 7-11.

King, G.F. Some effects of lateral sign displacement. Highway Research

Record, 1970, 325, 15-27.

King, G.F. , and Lunenfeld, H. Development of information requirements and

transmission techniques for highway users , Highway Research Board

NCHRP Reports , 1971.

Kolsrud, G.S. Diagrammatic Guide Signs for Use on Controlled Access

Highways, Volume III. Traffic Engineering Evaluation DiagrammatTc

Guide Signs, Part 3. Synthesis and Conclusions . Federal Highway

Administration, December 1972.

Lowry, P.R. , et al . A Survey of the Standard Poster Outdoor Advertising

Industry . Bureau of Public Roads , Bureau of Business ^ Economic

Research, Memphis State University Texas Transportation Institute,

Texas A^M University, 1967.

38
LovvT>', P.R. , Summer H.H., and Cartee, P.C. Economic Effects of the

Control of Highway Signs in Tennessee . Tennessee Department of

Highways and Bureau of Public Roads , Xovember 1967.

Mast, T.M. , Chernisk>% J.B., and Hooper, F.A., Jr. Diagrammatic Guide

Sign for Use on Controlled Access Plighways , Volume II. Laboratory.' , Instrumented Vehicle, and State Traffic Studies of Diagrammatic Guide , Signs . Federal Highway Administration, Decoiber 1972.

Matson, T.M. , Smith, K.S., and Hurd, F.W. Traffic Engineering . New York:

>fcGraw-Hill , 1955.

Middleton, W.E.K. A study of the conspicuit)' of orange surface colors.

Illuminating Engineering , Febiiaary 1952, 95-98.

Miller, G.A. The magical number seven, plus or minus t\v0, some limits on

our capacity for processing ir-formation . PsAxhological Review , March 1956,

63(2), 81-97.

~^

Miro-Flex Company, Inc. Sign Layouts , Interstate Highvvay Products,

Wichita, Kansas , 1971

.

National Aeronautics and Space Administration, Bioastronautics Data Book , U.S. Government Printing Office, 19"5.

National Academ>^ of Sciences , A'isual Factors in Transportation Systans . Proceedings of spring meeting, 1969, X\S-XRC Committee on Vision

(Miltiple Contributors) .

National Advertising Company. Letter Sizes and Color Combinations for

Interstate Highway Directional Signs , Research Departm.ent of National

Advertising Company, Argo, Illinois (undated).

Odescalcki, P. Conspicuit}' of signs in rural surroundings, Traffic

Engineering § Control , 1960, IjJ') , 390-3, 39'.

Pain, R. Brightness ratio as factors in the attention value of highway

signs, Highvray Research Record , 1969, 2"5 , 32-40.

Peterson, S.G., Schoppert, D.V*' . , Voorhees , A.M., and Associates. >fc)torist's

reactions to signing on a Belt\v-ay, Highway Research Record , 1967, 170 , 1-29.

Powers, L.D. Effectiveness of sign background reflectorization. Highway

Research Record , 1965, 7_0, 74-86.

Schoppert, D.W., Nfoskowitz, K. , Hulbert, S.F., and Burg, A. Seme principles

of freeway directional signing based on motorist's experiences. Highway

Research Board Bulletin, 1960, 244, 30-87.

39
Simon, A.L., and Rosenquist, H.S. Comprehensive Evaluation of Highway Sign

and Billboard Regulations . Akron University, Ohio, August 1967.

Solomon, D. The effect of letter width and spacing on night legibility of

highway signs. Proceedings of the Highway Research Board , 1956, 35,

600-617.

Straub, A.L., and Allen, T.M. Sign brightness in relation to position,

distance, and reflectorization. Highway Research Board Bulletin , 1956,

146, 13-34.

Texas Transportation Institute, Driver Communications and Traffic Control , November 1966.

U.S. Department of Transportation, Manual on Uniform Traffic Control

Devices for Streets and Highways , Federal Highway Administration, 1971

.

U.S. Department of Transportation, Standard Alphabets for Highway Signs , Federal Highway Administration, Office of Traffic Operations, 1966 edition.

Walton, N.E. Visibility and driver information. Highway Research Board

Record, 1973, 440, 1-19.

Woltman, H.L. Review of visibility factors in roadway signing. Highway

Research Board Special Report 134, Highway Visibility , 1973, 28-41.

Woods, D.L., and Rowman, N.J. Street name signs for arterial streets.

Highway Research Board , 1970, 325 , 51-61.

40
APPENDIX A

Sign Design Guidelines

"Schmillingrass Caverns," was used to illustrate sign design

principles . It used the same number of characters and spaces as the

longest, real destination name previously studied by FHIVA to respond to

the question of the Standards' adequacy (FB\A Correspondence #To-21, 1974).

For purposes of illustration and model testing the following assumptions

were met for the various configurations of "Schmillingrass Caverns"

signs. These design considerations were adapted from guidelines presented

in Standard .-Uphabets for Highway Signs (1972 reprint of 1966 edition) , from The Manual of Uniform Traffic Control Devices for Streets and

Highways C19"l) , and from information obtained directly fron

>tr. Travis Brooks, EHIVA, Office of Traffic Operations.

1. Character Height, Width and Stroke Width.

- Stroke ^sldth to height ratios for Series E letters and

numbers were used ( Standard Alphabets , 1966)

.

- Character widths employed maintained the same ratio to

character height as was specified for 10 in (25.4 cm) high

Series E characters.

- Characters were not restricted to standard sizes . Rather

characters that utilized all available height on the sign

Avere used, e.g., 15.02 in (38.15 am).

- Loop heights of lowercase (LC) characters in a given line

were set at 0.75 the height of the uppercase (UC) characters

in that line.

- For signs having two sizes of UC characters, the larger was

1.5 times the height of the smaller.

2. Spacing BetAceen Characters and Words.

- Spacing betiveen characters maintained the ratios specified in

Standard Alphabets for spacing betis^en 10 in (25.4 am) characters.

- Spacing betAveen words on the SCHMILLINGRASS Q/WmNS line equals

the "i\ldth of a fictitious UC "C" plus the spacing to the left

and right of that "C".

3. Spacing to Side Borders.

- Spacing from the first character of the longest line to the

left vertical border, and spacing from the last character to

the right border were each set equal to the height of the

UC characters on that longest line.

41
4. Interline Spacing

- The distance from the top border to the first line equalled

0.75 of the height of UC characters in that line.

- For configurations A and D, interline spacing was 0.75

UC character height.

- For configurations B and E, interline spacing was 0.75 the

height of the first "S" in Schmillingrass

.

- For configuration C, interline spacing was 0.33 character

height (Kindersley, 1966).

- Spacing to the bottom border was 0.75 the height of the UC

characters. (This differs slightly with guidelines in the

Manual on Uniform Traffic Control Devices , but was assumed for ease of computation.)

5. Line Length

- Only the length of the longest line was calculated since all

other lines will fall within the same limits.

6. Sign Height was determined as the sum of the number of lines of

text, interline spacings , and text-to-border spacings (expressed as proportions of character height)

.

7. Punctuation

- No periods were used after abbreviations.

42
Widths of Characters, Spaces and Resultant Lines of Text

for Four Configurations of "Schmillingrass Caverns " Widths

Expressed as Proportions of Uppercase Character Heights

Character

UC/LC line (or space) UC only line

Border to 1.000 -- 1st Character 1.000

.797 S .797 .313 .206

.633 C .797 .413 .206

.663 H .797 .513 .258 1.054 M .922

.513 .258

.188 I .1-^2 .513 .258 .188 L .734 .513 .206

,188 L .734

.513 .206

.188 I .172

•513 ,258 .640 N .797 .400 ,258 .633 G .797 .513 .258 .484 R .797 .200 .206

.633 A 1.000

.375 .206

.633 S .797

.233 .206

.633 S .797 Last character

1.000 -- to border 1,000

15.08 Subtotal-*- 15.10

Space bet\veen

1.209 ;,OTds 1.209

.797 C .797 .350 .137

.633 A 1.000

.375 .068 .742 V .906

.263 .206

.633 E .734

•413 ,206

.484 R .797 •313 .258 .640 N .797

.375 .258 .633 S .797 Last character

1.000 -- to border 1.000

22.94 -- Total-^ 23.27

Total 'Tilth or Line

•^SaiNfTLLINGRASS 13.10

^Schmillingrass 15.08

^Sai-.IILLIVGRASS Q\ri:R.vS 23 2^

2Schmillingrass Caverns 22.94

43

Appendix B

Siinmar)' of State Standards for Directional Signs

Table 10 presents a summary of pertinent provisions in various state

codes regarding directional signs . The first ten states listed had

previously submitted their codes to FHVA in accordance with provisions

in Section 21.4, Paragraph (f) (3) of the Standards. As part of the

preparation for field site measurements, those states near the Washington, D.C. area which had not yet submitted their codes were asked to provide

regulations applicable to similar t>'pes of signs.

The entries in the first line of Table 10 are from Part 21, Section 21.2

and 21.4 of the Standards. All entries of "standard" mean that the State

Code essentially replicates the Part 21 requirements for that point. FHIVA

responses to provisions less restrictive than the National Standards were

not studied for this project. Because cell entries are only brief

summaries , it will be necessary to refer to the State Code to clarify

some specific provisions, e.g. , the Number of Signs entry for Nebraska.

Mar>dand has special provisions for directional signs, so the comments

below relate to the remaining twelve states A\1iose Codes were examined.

Distance from Right-of -Way (R-O-W, within 660 ft (201 .2m) of the

nearest edge of R-O-W on Interstate (IS) and Federal -aid Primary

Syston (P) and v:hich are visible from the main tra\'"eled way of the system) .

- 8 states meet or exceed the Standards

.

- 3 states have not specified requirements

.

- 1 state refers to locations adjacent to and visible from the

main traveled way of IS and P.

2 2 Size (maximum: Area 150 ft ; Height 20 ft; Length 20 ft; or Avea 13.9 m

• Ee'ight 6.1 mj Length 6.1 m)

.

- All t\velve states comply with the Standards.

Moving (signs A\Mch move or have any animated parts are prohibited)

,

- 7 states meet the Standards (one of these mentions P but not IS)

.

- 5 states have not specified requirements

.

Spacing

a. (2,000 ft (609.6 m) minimum distance from an interchange or intersection

at grade along IS or other freeways.)

- 10 states meet the Standards (3 of these have other restrictions)

.

- 1 state specified 100 ft (SO. 5 m) minimum from an intersection

on any route or road.

- 1 state specified 500 ft (152.4 m)

.

45
b. (2,000 £t (609.6 m) minimum distance from a rest area, parkland,

or scenic area.)

- 8 states meet the Standards with respect to Federal -aid

primary (1 of these does not mention IS)

.

- 1 state did not specify this requirement.

- 3 states specified 500 ft (152.4 m)

.

c. (Separation of at least one mile (1.6 kilometers) from other

directional signs facing same direction of travel.)

- 9 states meet the Standards (1 of these does not mention IS)

.

- 1 state specified 0.5 mile (0.8 kilometers)

.

- 2 states mention shorter distances but are unclear as to how

they relate to the Standards

.

Number of Signs (Not more than three directional signs for same activity

facing same direction along a single route to the activity.)

- 11 states meet the Standards (1 of these does not mention IS)

.

1 state does not permit commercial signs along IS.

Distance from Activity (Signs to be within 75 air miles (120.7 kilometers)

along IS; within 50 air miles (80.5 kilometers) along P)

.

-10 states meet the Standards (1 of these does not specify air miles

and 1 requires signs to be within 5 air miles (8 kilometers) of

the advertised activity)

.

- 2 states did not specify for IS (1 of these also did not specify

for P) .

Content (Message limited to identification of the attraction and

directional information (mileage, route number, or exit numbers).)

- 9 states meet the Standards

.

- 3 states not clearly specified.

46
c

o ny c u

(U CJ §> S-3 P T3 facir S C (DC DO CS

iratior 250 £

or

IV

apart ction ft

of

.

se

sig

ft

of

se

sig

;

facin 1

of

tr

i

mile &it

At

least

1

signs

facii

of

travel

Standard Standard Standard Standard

i

Standard Minimum

of

Class

IV-A

1/2

mile

same

dire u

-a

CO

Standard

IS

-

5001

off-premi P

-

300

off-premi

All

signs

directior

least

one

Standard^ Standard

Spacing

Minimum

distance

From

Rest

area,

etc.

from

rest

rkland

,

rea

cified )f

public

Playgrounds,

i

ireas

,

Les2

limited

ligliway;

500

ft

Lted

access

2000

ft

area,

p£

scenic

£

Standarc Standarc Standarc

U

B 4

§

Not

spei

500

ft

Standari Standarc

500

ft(

parks,

I

scenic

;

cemetari Standarc

2000

ft

access

1

non-lim; highway

etc. V 3 4.J lU

o cO QJ -Cl. H 00 X

4-' 1 uS o

CQ O -Si 1 -M C *^ U

U U CO (U o

<y 25 x: ^

CL> %i

Minimum

dist

From

intersectii

2000

ft

on

Inter

system

or

other

Standard,

excepi

addition

of

'Vei

Stat

inn

Standard Standard Standard Standard

No

sign

within

11

intersection

on

route

or

road

500

ft

Standard Standard

2000

ft

from

inl

change

or

inters

orl

500

ft

of

interc

intersection,

s£

rest

areas

on

I£

with

full

access

control 2000

ft

of

freev

interchange

or 1

of

non-freeway

:

change 2000

ft,

limitec

highway;

500

ft,

limited

access

highway

ed

,

do

sion, re

with

,

device.

andard

Stable,

shield

not

improve

vi

do

not

interfe

traffic

signal

sign

Standard Standard

Not

specified

Standard Standard

Essentially

st

Standard

13U

§

CO

Standard

Not

specified

Standard Standard

Led o

ied

Moving

Do

not

move

and

have

nc

animated

oi

moving

pari 1

s+Jin

Standard

Not

specif]

Not

specif:

Standard o

Standard

Not

specif

Standard

Not

specif

Standard Standard

c

Standard Standard Standard Standard Standard Standard

Standard Standard Standard Standard

CO a Standard

B

_£o

Height (ft) o Standard Standard Standard

-a

T3C

*-i !/)

Standard Standard

Standard

tJ

(-

s

*-* CO

Standard Standard Standard Standard

(H W

o

Standard Standard Standard Standard Standard Standard

Standard standard Standard Standard Standard Standarc

SIGNS

"

and

system n L

rectiona]

jle

from

primary.

remarks)

ible way

of

RECTIONAl

Distance

from

R-t

660

ft

of

Interstate

Federal

-aid

primary

and

visible

from

mai

traveled

way

1

Standard 4

1 No

non-complying,

d:

signs

shall

be

visit

Interstate,

freeway

or

primary

highway^

'^Not

indicated

(see

Standard

Not

specified

Adjacent

to

and

vis

from

main

traveled

IS

and P

Standard Standard

Not

specified

Standard Standard,

NO

PROVISION

FOR

DI

State

,

Date

of

Code

DOT

Part

21

Section

21.2,

21.4

1/17/69

Illinois 7/11/72 Indiana 3/3/72 Iowa No

date Mississippi

10/1/72

Missouri 3/16/72Nebraska

No

date

Utah No

date

Virginia 10/29/70

Wisconsin

1971

IVyoming 1971 Oliio

p

CD2 S

o \2: r--

Maryland 7/1/68

47
o

-)-» z P tH . CO 1—I rH TD (-J S _

j_j 4_t O

{/I d -H

l/l Z CD •H (/) t/l OJ

Ih cTj a> CO

<L) Cl> 01 M

c; O -M L) • 3 1=: rH r-j

I O (D P- o I-H 3

clear signs, ear

.

not M C </l -M •HC -

if !Cti0 :

thi

LS

no o

cleai )

dire

lip

oi

:ion i

dist:

ited. s

not

ies

tc

tionst i£ica1

•H

CO cfl q; 61

.-H X CD

ta *-> -p

0) (h

[JU ^ (U

(/I a

Oi V) C ra (U o

•H X ca

-3 :3 -t^

l-J P O S-" CO

t3 -I-J H X

M §

ID 6 rH 4J

(U (1> -H CD

H tiO,-H U CT3 CO ^

(0 > c

!h -H O t O 4-* -H 6 U -H

CO O

CD O CD O CO -M bo X -M CD O 0^ JH

; 1/1 !-< s

1 r-J O CO

I < C4-4 Cn

M >

(3 -H o +-> r~( CJ CO CO

t3 to

CO t3 S O H LO O ^

rH O

48
APPENDIX C

to graphs and location maps

o^ risld sicms

49

Figure 7. #View of Harpers Ferry Caverns sign located in West Virginia

just south of Bolivar, West Virginia on US Route 340.

ROAD CLASSIFICATION

Primary highway, all weather, Light-duty road, all weather, hard surface — improved surface Secondary highway, all weather. Unimproved road, fair or dry hard surface . weather ....... (3 U- S. Route OS'^'* "o"'*

HARPERS FERRY. VA.-MD.-W. VA.

N3915—W7737 5/7 5

1969 AMS 5462 I SW-SERIES Ve34

QUAORANGLE LOCATION

Figure 7A. Approximate location of Harpers Ferry Caverns sign located in West

Virginia on US Route 340 just south of Bolivar, West Virginia (see Figures 7 and 8).

53

Figure 9. #View of Harpers Ferry Caverns sign located in West Virginia on US Route 340,

approximately one mile (1.6 kilometers) east of Halltown, West Virginia.

ROAD CLASSinCATION

Heavy-duty - Light-duty Medium-duty ._^i_=^_=_ Unimproved dirt

,

QU S. Route Q State Route

CHARLES TOWN. W. VA.—VA—MD

MARTINSBURG IS' QUADRANGLE N3915—W7745/7.5

W. VA. .

QUADR*NGLE LOariON

1955 PHOTOREVISEO 1971 AMS 5462 iV SE-SERIES V854

Figure 9A. Approximate location of Harpers Ferry Caverns sign located in West

Virginia on US Route 340, one mile (1.6 kilometers) east of Halltown, West

Virginia (see Figures 9 and 10).

57

4«

.now PEOPLE Set

Figure 1 1. #Luray Caverns sign typical of many such signs erected prior to Standards

spaced about 0.5 miles (0.8 kilometersj apart along highways in the area. This sign is located on US Route 340, approximately one mile (1.6

kilometers) west of Gaylord. Virginia. The sign in Figure 12 is barely

visible in this photograph in the lower left corner, right side of highway.

THE

k i CAVERNS'^im

MORE THAN MILUOH VtStTORSHAVEKEMAHAIg

Figure 12. #Luray Caverns sign located on US Route 340 just past the sign in Figure 1 1. rDoes not comply with 131(c) Standards. 59

ROAD CLASSIFICATION

Primaiy h^iway. all «eathef. Li^-dufy road, all weat'ier. haid ""fa^ impmed surface ==

Uninqinwed foad. ii« or diy weather .,

BERRYVILLE. VA. - W. VA.

N3907.5—W7752-5/7.5

PhOTORtVISED 1972 AMS 54S2 i:: NW_S£S1ES V354

Figure 1 lA. Approximate locations of Luray Caverns signs located one mile (1.6

kilometers) west of Gaylord, Virginia on US Route 340 (see Figures 1 1 and 12).

61

Figure 14. *Close-up view of Skyline Caverns sign located approximately

two miles (3.2 kilometers) south of Stephens City, Virginia on 1-81. #Does not comply with 13 l(c} Standards.

* Complies with 13 1(c) Standards. 63

ROAD CLASSIFICATION

Primary highway, all weather, Light-duty road, all weather,

hard surface improved surface Secondary highway, all weather. Unimproved road, fair or dry hard surface v/eather

Interstate Route QU. S, Route QState Route

QUADRANGLE LOCATION

NEW MARKET, VA.

NW/4 MT. JACKSOr 15 QUADRANGLE N3837.5—W7837.5/7.5

1967 AMS 5261 II NW_SERIES VB34

Figure 13A. Location of Endless Caverns sign on US Route 1

1

in New Market, Virginia (see Figure 13).

65

ROAD CLASSlFICATiON

Heavy-duty- ______ Ught-djty =_ Medium-duty- - Unimproved dirt

Interstate Route Q ^- ^- O """^^

VIRSIKIA ^

STEPHENS CITY, VA.

SW/« WINCHESTER 15 QUAC.RANGLE N3900—'.V7807.5/7.5

1966 AMS 5562 II SW-SERIES V854

Figure 14A. Approximate location of Skyline Caverns sign located two miles (3.2

kilometers) south of Stephens City, Virginia on 1-8 1 (see Figure 14).

67

Figure 15. *Road-side view of Endless Caverns sign located on 1-8 1 approximately 0.5 miles

(0.8 kilometers) south of Mauzy, Virginia. (Sign is located among trees

in upper right-hand comer of photograph. Apparently erected in 1971.)

XIT 66

Figure 16. *Close-up view of sign in Figure 15. (Trees in front of sign,

blocking view in Figure 15 are behind photographer.)

*CompIies with 131(c) Standards. 69

ROAD CLASSIFICATION

Primary highway, all weather. Light-duty road, all weather, hard surface improved surface =^=^=

Unimproved road, fair or dry weather —

(^Interstate Route Q^ ^ """'^ O^'^'^ """'^

TENTH LEGION, VA.

SW/4 MT. JACKSON 15 QUADRANGLE

OUADRiNGLE LOCATION AMS 5261 II SW_SERIES V834

Figure 15A. Approximate location of Endless Cavern sign located 0.5 miles (0.8

kilometers) south of Mauzy, Virginia on 1-8 1 (see Figures 1 5 and 16).

71

KYLIN

Caverns

SKYLINE DRIVE

Figure 1 7. *Close-up view of Skyline Caverns sign located approximately one mile

(1.6 kilometers) northeast of Middletown, Virginia on 1-81.

Strasburg 5

Roanoke 164

Figure 18. *Road-side view of sign in Figure 1 7. (Note close proximity to state erected mileage sign.)

Complies with 131(c) Standards. 73

ROAD CL^SSinCATlON

Heavy-duty Ught-dii-ty ===

Medium-duty - _=_=_ Unimproved dirt ===.^=,» =

IntEfSlBtE Routs [3 U S- Route Q State Route

MIDDLETOWN. VA.

N39CC—'.V7S15/

(3fJtatAMCi£ LOCATION

1966 PH0TCREV13ED 1972 AMS 5362 III SE-SERIES V834

Figure 17A. Approximate location of Skyline Caverns sign located on 1-81, one mile

(1.6 kilometers) northeast of Middletown, Virginia (see Figures 17 and 18).

75

Figure 19. *Road-side view of Skyline Caverns sign located on 1-66, approximately

three miles (4.8 kilometers) south of Reliance, Virginia.

Figure 20. *Close-up view of sign in Figure 1 9.

*Complies with 131(c) Standards. 77

ROAD CLASSIFICATION Heav^ii^ Li^-du^ =_=

MaSum-duty UnimiviMai dirt

IntsfsJste Route Q O

STRASBURG. VA.

KE/4 STj?AS3-'SG ;S iL-*0.=^-O»"C". N3852-5—ViTSlS. 7.5

19-66 PHOTOREVISED 1972

AiCS 5351 IV NE-3ESiE3 VS3*

Figure 19A. Approximate location of Skyline Caverns sign located on 1-66, three miles

(4.8 kilometers) south of Reliance, Virginia (see Figures 19 and 20).

79

Figure 21. ©Right-of-way sign for "Caverns" located on US Route 340, approximately

0.5 miles (0.8 kilometers) north of Luray, Virginia.

Figure 22. ©Right-of-way sign for "Caverns" located just off Route 211,

approximately 0.25 miles (0.4 kilometers) south of Luray Caverns.

@State-erected right-of-way sign for caverns destination. 81

ROAD CLASSinCATtCN

Hea«y-duty _ Lighiriuiy MeiSunvdu^- Unimproved dirt

,

QU. S. R0L1E QSt2tE Riiite

LURAY, VA.

N3857.5—W7822.5/7.5

1965 PHOTOREVISED 1972 AMS 5561 m NW-SER!tS V854

Figure 21A. Approximate location of right-of-way sign for "Caverns" located on US

Route 340. 0.5 miles (0.8 kilometers) north of Luray. Virginia (see Figure 21).

83

ROAD CLASSIFICATION

Heavy-duty Light-duty =

Medium-duty Unimproved dirt ^- Q U. S. Route Q State Route

QUADRANSIX LOCATION

LURAY, VA.

N3837.5—W7822. 5/7.5

1965 PH0T0REVI3ED 1972 AMS 5361 111 NW-SERIES V834

Figure 22A. Approximate location of right-of-way sign for "Caverns" located just off

US Route 211, 0.25 miles (0.4 kilometers) south of Luray Caverns (see Figure 22).

85

Figure 23. ©Right-of-way sign for Shenandoah Caverns located on 1-81, approximately

1.25 miles (2 kilometers) east of Quicksbun,', Virginia. (Similar sign at Route 730 Exit.)

@State-erected right-of-way sign for caverns destinatioa. 87

ROAD CLASSIFICATION

Primary highway, all weather, Light duty road, all weather, hard surface improved surface Secondary highway, all weather. Unimproved road, fair or dry hard surface weather

Interstate Route

(__J U. S. Route QState Route

NEW MARKET, VA.

NW/4 MT- JACKSON 15 QUADRANGLE N3837.5—W783 7 5/7.5

1967

aUAORANGLE LOCATION ^^S 5261 II NW-SERIES V8J4

Figure 23A. Approximate location of right-of-way sign for Shenandoah Caverns located on 1-81, 1.25 miles (2 kilometers) east of Quicksburg, Virginia (see Figure 23).

89

Figure 24

Kings Island

Aimisenient Center

Kbtae Mills. Ohio

Fic^ire 25

91

APPENDIX D

Consultant Vitae

Dr. Theodore W. Forbes

Dr. Forbes is Professor of Psychology and research advisor, Highway

Traffic Safety Center at Michigan State University. He teaches graduate

courses in Engineering Psychology and carries on human factor research

under the Division of Engineering Research. He obtained his A.B. and

M.S. from Oberlin College and his Ph.D. from Ohio State University in

fields of applied and experimental psychology and was a Fellow at the

Harvard Traffic Bureau and a staff member of the Yale Traffic Bureau.

He has authored research reports in a variety of fields , including Traffic

Sign Legibility, Driver Judgments and Responses, Human Factors in Traffic

Flow Theory, Drowsiness in Driving, Air Photo Traffic Data, s.nd Effects

of Tunnel Conditions on Driving Behavior. He performed some of the

earliest human engineering research in connection with highway sign studies

at the Yale Bureau of Highway Traffic. He is a member of a number of

scientific and professional societies in human factor and engineering

fields

.

Example publications include:

Forbes, T.W. A method for analysis of the effectiveness of highway signs.

Journal of Applied Psychology , 1939, XXIII, No. 6, 669-684.

Forbes, T.W. Highway sign luminance, contrast, visibility and legibility.

Presented at: 7th IRF World Meeting, Niinich, West Germany, October 16, 1973.

Forbes, T.W. , Pain, R.F. , Fry, J. P., Jr § Joyce, R.P. Effect of sign

position and brightness on seeing simulated highway signs. Highway

Research Record , 1967, 164, 29-37.

Forbes, T.W., Pain, R.F., Joyce, R.P. ^ Fry, J. P. Jr. Color and brightness

factors in simulated and full-scale traffic sign visibility. Highway

Research Record , 1968, 216, 55-65.

Forbes, T.W., Snyder, T.E., and Pain, R.F. A study of traffic sign

requirements II. An annotated bibliography, Michigan State University,

East Lansing, Michigan, 1964, 65.

Forbes, T.W. , Snyder, T.E., and Pain, R.F. Traffic sign requirements I. Review of factors involved. Previous studies and needed research.

Highway Research Record , 1965, 70, 48-56.

Dr. Slade F. Hulbert

Dr. Hulbert has been a research psychologist with UCLA since 1952.

Since that time he has been active in: Human Factors research in

transportation systems. Engineering Education, and Psychological Behavior

Theories. He has had extensive experience consulting in these areas with numerous national, state, and local governmental agencies.

93
He has authored and co-authored several textbook chapters and

40 research articles and reports having to do with driver behavior.

Dr. Hulbert is a Fellow of the Human Factors Society of Merica

and recipient of the Society's 1972 A.R. Lauer Award; Fellow of the

Institute of Traffic Engineers; a member of the American Psychological

Association; Sigma Xi ; Training Committee of the Society of Automotive

Engineers ; Driving Simulation Committee and Bicycle Committee of the

Transportation Research Board of the National Academy of Sciences and

Engineering; Panel on Human Error in Maritime Accidents, Maritime Research

Board; Research Advisor to the National Joint Committee for Uniform

Traffic Control Devices ; Consultant to the National Highway Traffic

Safety Administration, U.S. Department of Transportation; and is a Licensed Psychologist in the State of California.

Example publications include:

Beers, J., and Hulbert, S. Research and development of the changeable

message concept of freeway traffic control, Highway Research Board

Special Report , July 1972, 129.

Burg, A. , and Hulbert, S. Dynamic visual acuity as related to age, sex,

and static acuity. Journal of Applied Psychology , 1961, 45(2), 111-116.

Hulbert, S.F. Evaluation of highway destination signs. Proceedings , Seventh California Street and Highway Conference , University of

California, Berkeley, 1955, 122-124.

Hulbert, S.F., and Burg, A. Predicting the effectiveness of highway signs,

Highway Research Board Bulletin, 1962, 324, 1-11.

Hulbert, S.F., and Burg, A. Human factors in transportation systems.

Systems Psychology , (K.B. DeGreene, Ed.), McGraw-Hill, 1970, 471-509.

Schoppert, D.W., Moskowitz, K., Hulbert, S.F., and Burg, A. Some principles

of freeway directional signing based on motorist's experiences. Highway

Research Board Bulletin , 1960, 244, 30-87.

Dr. L. Ellis King

Dr. King has pursued the practical application of laboratory and field

data to highway signing and lighting problems . Previous work has included

analysis of the ability of drivers to process graphic, directional and

driving information and other nonverbal messages. He holds B.S.C.E. and

M.S.CE. degrees in transportation engineering from North Carolina State

University and the D.Eng. degree from the University of California at

Berkeley and was Director of the Transportation Systems Program at West

94
Virginia University from 1971 to 1973. Now an Associate Professor of

Civil and Environmental Engineering at the University of Colorado at

Denver and Associate Director of the Center for Urban Transportation

Studies, he was awarded a Walter L. Huber Civil Engineering Research Prize

by the American Society of Civil Engineers in 1973.

Recent publications include:

King, L.E. Recognition of symbol and word traffic signs. Journal of

Safety Research National Safety Council (accepted for publication)

.

King, L.E. A laboratory comparison of symbol and word roadway signs,

Traffic Engineering ^ Control , London, February 1971, 12^(10), 518-520.

King, L.E. Highway lighting - design for luminance. Traffic Engineering , February 1973, 43(5), 32-33, 50.

King, L.E., and Campbell, R.E. The traffic conflicts technique applied

to rural intersections. Accident ^ Prevention , December 1970, 2_(3) , 209-221.

King, L.E., and Plummer, R.W. Field investigation of driver understanding

of left turn signal indication sequences, Proceedings of the 16th

Annual Human Factors Meeting , Los Angeles, California, October 17-19, 1972.

King, L.E., and Plummer, R.W. Meaning and application of color and arrow

indications for traffic signals. Final report. Engineering Experiment

Station, West Virginia University, April 1973.

Dr. Thomas H. Rockwell

Dr. Rockwell is now Professor of Industrial Engineering and Systems

Engineering at the Ohio State University. He holds M.S. and Ph.D. degrees

in Industrial Engineering and has directed over 60 M.S. and Ph.D. candidates

in Traffic Accident Research. Since the mid-1960 's, he has been on the

Scientific Advisory Board for Operations Research at Nationwide Insurance,

and a consultant to the U.S. Department of Health, Education, and Welfare;

U.S. Public Health Service; Wright-Patterson Air Force Base; Bureau of

Labor Statistics; Department of Ohio Transportation; Ford Motor Conpany;

and the National Highway Traffic Safety Administration. Professional

membership is held in: Sigma Xi, American Institute of Industrial

Engineers; Fellow of the Human Factors Society; Transportation Research

Board (National Academy of Sciences) ; Fellow of the American Association

for the Advancement of Science and the American Association of Autcmotive

Medicine. Awards for traffic/driver research have been received from the

Ohio Society of Professional Engineers and the Human Factors Society

(1970, 1971).

95
Recent publications include:

Rockwell, T.H., and Bhise, V.D. Evaluation of visual field requirements

of vehicles in freeway merging situations, Proceedings, 16th Annual

Meeting of Human Factors Society , Beverly Hills, California,

October 1972.

Rockwell, T.H., and Bhise, V.D. Toward the development of a methodology

for evaluating highway signs based on driver information acquisition.

Highway Research Record , Washington, D.C. , 1973, 440 .

Rockwell, T.H., and Lindsay, G.F. Freeway illumination and driving

performance. Traffic Engineering , March 1969, 39(6), 36.

Rockwell, T.H., and Mourant, R.R. Mapping eye -movement patterns to the

visual scene in driving: an exploratory study. Human Factors

February 1970, 12(1), 81-87.

Rockwell, T.H., and Mourant, R.R. Maximum driving performance- -can it

be predicted? Proceedings , Symposium on Psychological Aspects of

Driving Behavior , Noordwij kerhout , Netherlands, August 1971.

Rockwell, T.H., and Mourant, R.R. Strategies of visual search by novice

and experienced drivers, Hum.an Factors , August 1972, 14(4) .

96
APPENDIX E

J 5 for Directional

Other Gfficia' big!

U.S. DEPARTMENT OF TRANSPORTATION

FEDERAL HIGHWAY ADMINISTRATION

BUREAU OF PUBLIC ROADS

WASHINGTON. D.C 20591

FEBRUARY 1969

97
Title 23—HIGHWAYS

Chapter I —Bureau of Public Roads, Department of Transportation

PART 21—NATIONAL STANDARDS

FOR DIRECTIONAL AND OTHER

OFFICIAL SIGNS

The purpose of this amendment is to add a new- Part 21—National Standards

for Directional and Other Officials Signs—to chapter I of title 23 of the

Code of Federal Regulations. The new

part will include all national standards

established under section 131(c)(1) of

title 23, United States Code.

Section 303 1'a) of the Highway Beautification Act of 1965 (Public Law 89-285)

requires public hearings to be held in each State by the Secretary before issu- ing standards necessary to carry out sec- tion 131 of title 23, United States Code.

Notice of the public hearings was published in the Federal Register on January 28. 19G6 (31 F.R. 1162). Pursuant to this notice, public hearings were conducted in each State, the

District of Columbia, and Puerto Rico. Based on the testimony received at the

52 public hearings which were held, draft standards were developed. The

draft standards were jiven wide circula- tion among the outdoor advertising in- dustry, roadside councils, garden clubs. State highv/ay departments, and other

interested groups. Com.ments thereon were evaluated and given fall consideration in the preparation of the proposed standards. On January 10, 1967, proposed national standai-ds for directional and

official signs were reported to Congress

by the Secretary in accordance with section 303 (b; of the Highway Beautification Act of 1965, and printed as Senate

Document No. 6, 90th Congress, first session. Thereafter proposed standards were

distributed to che States, the District of Columbia, and Puerto Rico, and other

interested parties for comment.

A review of the proposed national

standards and all additional comments

and recommendations submitted as a

result of the distribution has been completed with all such pertinent matter,

recommendations and comments having

been fully considered and evaluated. The national standards added by this amendment are minimum standards. They have been developed in cooperation

with the States and other interested or- ganizations, groups, and individuals. In consideration of the foregoing.

Chapter I of title 23, Code of Federal Regulations is amended by adding

a new Part 21. "National Standards for Directional and Other Oflicial Signs"

as set forth below, effective February 25, 1S69. This amendment is made under authority of sections 131 and 315 of title 23, United States Code, section 6fa)(l)

(H) of the Department of Transportation Act (Public Law 89-670. 80 Stat. 931). and the delegation of authority

contained in Part 1 of the Regulations

of the Office of the Secretary of Transportation (49 CFR 1.4(c)). Issued in Washington, DC, on January 17, 1969. Lowell K. Bridwell,

Federal Highway Administrator.

Sec.

21.1 Purpose.

21.2 Application.

21.3 Definitions.

21.4 Standards for directional signs. 21.5 State standards. A-yTHORrrr: The provisions of this Part

21 l.ssxied under sees. 131 and 315 of title 23, use. sec. 6 (a)(1)(H), Department of Transportation Act (Public Law 83-670, 80

Stat. 931): d'3legatlon of authority to 49 CFU 1.4(c). §21,1 Purpose.

(a) In section 131 of title 23, United

States Code, Congress has declared that:

(1) The erection and maintenance of outdoor advertising signs, displays, and

devices Ln areas adjacent to the Interstate System and the primary system

should be controlled in order to protect

the public investment in such highways,

to promote safety and recreational value

of public travel, and to preserve natural beauty.

(2) Directional and other official signs

and notices, which signs and notices shall include, but not be limited to, signs and

notices pertaining to natural wonders,

scenic and historical attractions, which

are required or authorized by law, shall conform to national standards authorized to be promulgated by the Secretary,

which standards shall contain provisions

concerning the lighting, size, number and

spacing of signs, and such other requirements as may be appropriate to implement the section.

(b) The standards in this part are is- sued as provided in section 131 of title 23, United States Code.

98
§ 21.2 Application.

The following st-andards apply to di- rectional and other official signs and notices which are erected and maintained

within 660 feet of the nearest edge of the right-of-way of the Interstate and

Federal-aid primary system, and which

axe visible from the main traveled way of the system. These standards do not

apply to directional and other official signs erected on the highway right-cf- way.

§ 21.3 Definitions. For the purpose of this part

(a) "Sign" means an outdoor sign,

light, display, device, figure, painting,

drawing, message, placard, pester, bill- board, or other thing which is designed,

intended, or used to advertise or inform,

any part of the advertising or informative contents of which is visible from

any place on the main traveled way of the Interstate or Federal-aid primary

highway.

(b) '".lain traveled way" means the through trafnc lanes of the highway, exclusive o: frontage roads, auxUiars' lanes,

and ramps.

(c) "Interstate s^'stem" means the National System of Interstate and "De- fense Highways described in section 103(d) of title 23, United States Cede.

(dJ "Primary system" means the Federal-aid highway system described

in section 103(b) of title 23. United

States Code.

(e) "Erect" means to construct, build,

raise, assemble, place, affix, attach,

create, paint, draw, or in any other way

bring into being or establish.

(f) "Maintain" means to allow to

exist. (g) "Scenic area" m.ear-s any area of

partictilar scenic beauty or historical significance as determ.ined by the Federal, State, or local officials having juris- diction thereof, and includes interests In land which have been acquired for the

restoration, presentation, and enhancement of scenic beauty.

(h) "Parkland" means any publicly

ov.TLed land which is designated or used

as a public park, recreation area, wildlife or waterfowl refuge or historic site.

(i) "Federal or State law" means a

Federal or State constitutional provision or statute, or an ordinance, rule, or regulation enacted or adopted by a State

or Federal agency or a political subdivision of a State ptu-suant to p. Federal

or State constitution or statute.

(j) "Visible" means capable of being

seen (whether or not legible) without

visual aid by a person of normal visual

acuity.

(k) "Freeway" means a divided arterial highway for through traffic i full control of access.

(1) "Rest area" means an area or site established and maintained within or adjacent to the highv.'ay right-of-way

by or under public supen'ision or control

for the convenience of the traveling

puW^f..

<.m "Directional and other official signs and notices" includes only official signs and notices, public utility signs, service club and religious notices, public

ser\ice signs, and directional signs.

(n) "Official signs and notices" means

signs and notices erected and maintained

by pubhc officers or public agencies

within their territorial or zoning juris- diction and pursuant to and in accord- ance with direction or authorization contained in Federal. State, or local law for the purposes of carrying out an official duty or responsibility. Historical markers authoilsed by State law and erected by State or local government agencies

or nonprofit historical societies may be

considered official signs.

(0) "Ptiblic utihty signs" means warning signs, informational signs, notices, or markers which are customarily

erected and maintained by publicly or

privately owned public utilities, as essential to their operations.

(p) "Service club and religious notices" means signs and notices, whose

erection is authorized by law. relatmg to meetings of nonprofit service clubs or

charitable associations, or reUgious services, which signs do not exceed 8 square

feet in area.

(q) "Public service signs" means signs located on school bus stop shelters, wMch

signs

(1) Identify the donor, sponsor, or

contributor of said shelters;

(2) Contain safety slogans or m.essages, which shall occupy not less than

60 percent of the area of the sign;

(3) Contain no other message;

99
(4) Are located on school bus shelters which are authorized or approved by

city, county, or State law, regulation, or ordinance, and at places approved by the

city, county, or State agency controllinfj

the highway involved; and

(5) May not exceed 32 square feet in area. Not more than one sign on eacn

shelter shall lace In any one direction.

kt) "Directional signs" means signs

containing directional information about

public places o^;vned or operated by Federal, State, or local governments or their agencies; publicly or privately owned

natural phenomena, historic, cultural,

scientific, educational, and religious

sites; and areas of natural scenic beauty

or naturally suited for outdoor recreation, deerried to be in the interest of the

traveling public.

(s) "State" m.eans any one of the 50

States, the District of Columbia, or Puerto Rico.

§ 21.4' •Standards for directional sij^ns. The following appiy only lu directional signs

:

(a) General. The following signs are prohibited:

(1) Signs advertising activities that

are illegal under Federal or State laws

or regulations in effect at the location

of those signs or at the location of those

activities. (2 > Signs located in such a manner as

to obscure or otherwise interfere with

the effectiveness of an official traffic sign,

signal, or device, or obstruci or interfere with the driver's view of approaching,

merging, or intersecting traffic. (3) Signs which are erected or maintained upon trees or painted or drawn

upon rocks or other natural features.

(4) Obsolete signs.

(5) Signs which are structurally

unsafe or in disrepair.

(6) Signs which move or have any

animated or moving parts.

(7) Signs located in rest areas, parklands or scenic areas.

vD) Size. (1) No sign shall exceed the

following limits:

(I) Maximum area—150 square feet.

(II) Maximum height—20 feet.

(III) Maximum len^h—20 feet. \2) All dimensions include border and

trim, but exclude supports.

(c) Lighting. Signs may be illum.i- nated, subject to the following

:

(1) Signs \\hich contain, include, or are illuminated by any P.asliing, inter- mittent, or moving light or lights are

prohibited.

(2) Signs which are not effectively

shielded so as to prevent beams or rays

of light from being directed at any portion of the traveled way of an Interstate or primary highv.-ay or which are of such

intensity or brilliance as to cause glare

or to impaif the vision of the driver of any motor vehicle, or which otherwise

interfere with any driver's operation of a motor vehicle are prohibited.

(3) No sign may be so illuminated as

to interfere with the effectiveness of or obscure an official trafRc sign, device, or

signal.

(d) Spacing. (1) Each location of a

directional sign m.ust be approved by

the State highway department.

(2) No directional sign may be located within 2.090 feet of an interchange, or intersection at grade along the Interstate System or other freeways (measured

along the Interstate or freeway from the

nearest point of the beginning or ending

of pavement widening at the exit from or entrance to tlie main traveled w ay •

.

(3; No directional sign may bo lo- cated within 2,000 feet of a rest area, parkland, or scenic area.

(4) (i) No two directional signs fac- ing the same direction of travel shall be

spaced less than 1 mile apart,

(ii) Not more than three directional signs pertaining to the same activity and

facing the same direction of travel may

be erected along a single loute ap- proaching the activity;

(iii) Signs located adjacent to the Interstate System shall be within 75 air miles of the activity ; and

(iv) Signs located adjacent to the Primary System shall be witnin 50 air mdes of the activity.

(e) Message content. The message on

directional signs shall be limited to the

identification of the attracLion or activity and directional information useful

to the traveler in locating the attraction,

such as mileage, route numbers, or exit numbers. Descriptive words or phrases,

and pictorial or photographic representations of the activity or its environs are

prohibited.

100
(f) Selection viethods and criteria. (1) Privately ov/ned activities or at- tractions ciigible for circccionai sirrnine are limited to the loilowing: natural phenotnena; scenic attractions; historic,

educational, cultural, sc»ent;iic. and religious sites; and outdoor recreational

areas.

(2) To be eligible, privately owned at- tractions cr activities mist be nationally or regionally knov/n, and of outstanding

interest to the traveling public.

(3) Each State .shall develop specific selection methods and criteria to be used

in determinirig whether or no^ an activity qualifies for this type cf signing. A

statement as to selection methods and

criteria shall be furnished to the Secretary of Transportation before the State permits the sreciion of any r,uch signs

under section 131 (c) of title 23, United

States Code, and this part.

§21.5 Stale stantiards. This part does not prohibit a State from establishing and maintaining

standards which are more restrictive with respect to directional and other

official signs and notices along tne Federal-aid highv/ay systems than these national standards.

iF.R. Doc. 69-831; Filed, Jan. 22, 1969; 8:50 a.m.

J

101