Chapter 2E. Guide Signs—Freeways and Expressways
Section 2E.01 Scope of Freeway and Expressway Guide Sign Standards
Support:
These standards provide a uniform and effective system of highway
signing for high-volume, high-speed motor vehicle traffic on freeways
and expressways. The requirements and specifications for expressway
signing exceed those for conventional roads (see Chapter
2D), but are less than those for freeway signing. Since there
are many geometric design variables to be found in existing roads,
a signing concept commensurate with prevailing conditions is the
primary consideration. Section
2A.01 includes definitions of freeway and expressway.
Guide signs for freeways and expressways are primarily identified by the name of the sign rather than by an assigned sign code. Guidelines for the design of guide signs for freeways and expressways are provided in Chapter 8 (Design Guidelines) of the "Standard Highway Signs" book (see Section 1A.11).
Standard:
The standards prescribed herein for freeway or expressway guide
signing shall apply to any highway that meets the definition of
such facilities.
Section 2E.02 Freeway and Expressway Signing Principles
Support:
The development of a signing system for freeways and expressways
is approached on the premise that the signing is primarily for the
benefit and direction of road users who are not familiar with the
route or area. The signing furnishes road users with clear instructions
for orderly progress to their destinations. Sign installations are
an integral part of the facility and, as such, are best planned
concurrently with the development of highway location and geometric
design. For optimal results, plans for signing are analyzed during
the earliest stages of preliminary design, and details are correlated
as final design is developed. The excessive signing found on many
major highways usually is the result of using a multitude of signs
that are too small and that are poorly designed and placed to accomplish
the intended purpose.
Freeway and expressway signing is to be considered and developed as a planned system of installations. An engineering study is sometimes necessary for proper solution of the problems of many individual locations, but, in addition, consideration of an entire route is necessary.
Guidance:
Road users should be guided with consistent signing on the approaches
to interchanges, when they drive from one State to another, and
when driving through rural or urban areas. Because geographical,
geometric, and operating factors regularly create significant differences
between urban and rural conditions, the signing should take these
conditions into account.
Guide signs on freeways and expressways should serve distinct functions as follows:
- Give directions to destinations, or to streets or highway routes, at intersections or interchanges;
- Furnish advance notice of the approach to intersections or interchanges;
- Direct road users into appropriate lanes in advance of diverging or merging movements;
- Identify routes and directions on those routes;
- Show distances to destinations;
- Indicate access to general motorist services, rest, scenic, and recreational areas; and
- Provide other information of value to the road user.
Section 2E.03 General
Support:
Signs are designed so that they are legible to road users approaching
them and readable in time to permit proper responses. Desired design
characteristics include: (a) long visibility distances, (b) large
lettering and symbols, and (c) short legends for quick comprehension.
Standard:
Standard shapes and colors shall be used so that traffic signs can
be promptly recognized by road users.
Section 2E.04 Color of Guide Signs
Standard:
Guide signs on freeways and expressways, except as noted herein,
shall have white letters, symbols, and borders on a green background.
Support:
Color requirements for route signs and trailblazers, signs with
blank-out or changeable messages, signs for services, rest areas,
park and recreational areas, and for certain miscellaneous signs
are specified in the individual sections dealing with the particular
sign or sign group.
Section 2E.05 Retroreflection or Illumination
Standard:
Letters, numerals, symbols, and borders of all guide signs shall
be retroreflectorized. The background of all guide signs that are
not independently illuminated shall be retroreflective.
Support:
Where there is no serious interference from extraneous light sources,
retroreflectorized ground-mounted signs usually provide adequate
nighttime visibility.
On freeways and expressways where much driving at night is done with low-beam headlights, the amount of headlight illumination incident to an overhead sign display is relatively small.
Guidance:
Overhead sign installations should be illuminated unless an engineering
study shows that retroreflectorization alone will perform effectively.
The type of illumination chosen should provide effective and reasonably
uniform illumination of the sign face and message.
Section 2E.06 Characteristics of Urban Signing
Support:
Urban conditions are characterized not so much by City limits or
other arbitrary boundaries, as by the following features:
- Mainline roadways with more than two lanes in each direction;
- High traffic volumes on the through roadways;
- High volumes of traffic entering and leaving interchanges;
- Interchanges closely spaced;
- Roadway and interchange lighting;
- Three or more interchanges serving the major City;
- A loop, circumferential, or spur serving a sizable portion of the urban population; and
- Visual clutter from roadside development.
Operating conditions and road geometrics on urban freeways and expressways usually make special sign treatments desirable, including:
- Use of Interchange Sequence signs (see Section 2E.37);
- Use of sign spreading to the maximum extent possible (see Section 2E.10);
- Elimination of service signing (see Section 2E.51);
- Reduction to a minimum of post-interchange signs (see Section 2E.35);
- Display of advance signs at distances closer to the interchange, with appropriate adjustments in the legend (see Section 2E.30);
- Use of overhead signs on roadway structures and independent sign supports (see Section 2E.22);
- Use of diagrammatic signs in advance of intersections and interchanges (see Section 2E.19); and
- Frequent use of street names as the principal message in guide signs.
Lower speeds which are often characteristic of urban operations do not justify lower signing standards. Typical traffic patterns are more complex for the road user to negotiate, and large, easy-to-read legends are, therefore, just as necessary as on rural highways.
Section 2E.07 Characteristics of Rural Signing
Support:
Rural areas ordinarily have greater distances between interchanges,
which permits adequate spacing for the sequences of signs on the
approach to and departure from each interchange. However, the absence
of traffic in adjoining lanes and on entering or exiting ramps often
adds monotony or inattention to rural driving. This increases the
importance of signs that call for decisions or actions.
Guidance:
Where there are long distances between interchanges and the alignment
is relatively unchanging, signs should be positioned for their best
effect on road users. The tendency to group all signing in the immediate
vicinity of rural interchanges should be avoided by considering
the entire route in the development of sign plans. Extra effort
should be given to the placement of signs at natural target locations
to command the attention of the road user, particularly when the
message requires an action by the road user.
Section 2E.08 Memorial Highway Signing
Guidance:
Freeways and expressways should not be signed as memorial highways.
If a route, bridge, or highway component is officially designated
as a memorial, and if notification of the memorial is to be made
on the highway right-of-way, such notification should consist of
installing a memorial plaque in a rest area, scenic overlook, recreational
area, or other appropriate location where parking is provided with
the signing inconspicuously located relative to vehicle operations
along the highway.
Option:
If the installation of a memorial plaque off the main roadway is
not practical, a memorial sign may be installed on the mainline.
Standard:
Where such memorial signs are installed on the mainline, (1) memorial
names shall not appear on directional guide signs, (2) memorial
signs shall not interfere with the placement of any other necessary
highway signing, and (3) memorial signs shall not compromise the
safety or efficiency of traffic flow. The memorial signing shall
be limited to one sign at an appropriate location in each route
direction.
Section 2E.09 Amount of Legend on Guide Signs
Guidance:
No more than two destination names or street names should be shown
on any Advance Guide sign or Exit Direction sign. A City name and
street name on the same sign should be avoided. Where two or three
signs are placed on the same supports, destinations or names should
be limited to one per sign, or to a total of three in the display.
Sign legends should not exceed three lines of copy.
Option:
Sign legends may include symbols, route numbers, arrows, cardinal
directions, and exit instructions.
Section 2E.10 Number of Signs at an Overhead Installation and Sign Spreading
Guidance:
If overhead signs are warranted, as set forth in Section
2A.17, the number of signs at these locations should be limited
to only those essential in communicating pertinent destination information
to the road user. Exit Direction signs for a single exit and the
Advance Guide signs should have only one panel with one or two destinations.
Regulatory signs, such as speed limits, should not be used in conjunction
with overhead guide sign installations. Because road users have
limited time to read and comprehend sign messages, there should
not be more than three guide signs displayed at any one location
either on the overhead structure or its support.
Option:
At overhead locations, more than one sign may be installed to advise
of a multiple exit condition at an interchange. If the roadway ramp
or crossing roadway has complex or unusual geometrics, additional
signs with confirming messages may be provided to properly guide
the road user.
Support:
Sign spreading is a concept where major overhead signs are spaced
so that road users are not overloaded with a group of signs at a
single location. Figure 2E-1 illustrates an example of sign spreading.
Figure 2E-1 Example of Guide Sign Spreading
Guidance:
Where overhead signing is used, sign spreading should be used at
all single exit interchanges and to the extent possible at multi-exit
interchanges. Sign spreading should be accomplished by use of the
following:
- The Exit Direction sign should be the only sign used in the vicinity of the gore (other than the Gore sign). It should be located overhead near the theoretical gore and generally on an overhead sign support structure.
- The Advance Guide sign to indicate the next interchange exit should be placed near the crossroad location. If the crossroad goes over the mainline, the Advance Guide sign should be placed on the overcrossing structure.
Section 2E.11 Pull-Through Signs
Support:
Pull-Through signs (see Figure 2E-2) are overhead lane use signs
intended for through traffic.
Figure 2E-2 Pull-Through Signs
Guidance:
Pull-Through signs should be used where the geometrics of a given
interchange are such that it is not clear to the road user as to
which is the through roadway, or where additional route guidance
is desired. Pull-Through signs with down arrows should be used where
the alignment of the through lanes is curved and the exit direction
is straight ahead, where the number of through lanes is not readily
evident, and at multi-lane exits where there is a reduction in the
number of through lanes.
Section 2E.12 Designation of Destinations
Standard:
The direction of a freeway and the major destinations or control
cities (see Section 2D.34)
along it shall be clearly identified through the use of appropriate
destination legends. Successive freeway guide signs shall provide
continuity in destination names and consistency with available map
information. At any decision point, a given destination shall be
indicated by way of only one route.
Guidance:
Control city legends should be used in the following situations
along a freeway:
- At interchanges between freeways;
- At separation points of overlapping freeway routes;
- On directional signs on intersecting routes, to guide traffic entering the freeway;
- On Pull-Through signs; and
- On the bottom line of post-interchange distance signs.
Support:
Continuity of destination names is also useful on expressways serving
long-distance or intrastate travel.
The determination of major destinations or control cities is important to the quality of service provided by the freeway. Control cities on freeway guide signs are selected by the States and are contained in the "List of Control Cities for Use in Guide Signs on Interstate Highways," published and available from American Association of State and Highway Transportation Officials (see Addresses for AASHTO's address).
Section 2E.13 Size and Style of Letters and Signs
Standard:
With all freeway and expressway signs, the message dimensions shall
be determined first, and the outside sign dimensions secondarily.
Word messages in the legend of expressway guide signs shall be in
letters at least 200 mm (8 in) high. Larger lettering shall be used
for major guide signs at or in advance of interchanges and for all
overhead signs. Minimum numeral and letter sizes for expressway
guide signs according to interchange classification, type of sign
and component of sign legend are shown in Tables 2E-1 and 2E-2.
Minimum numeral and letter sizes for freeway guide signs, according
to interchange classification, type of sign, and component of sign
legend, appear in Tables 2E-3 and 2E-4. All names of places, streets,
and highways on freeway and expressway guide signs shall be composed
of lower-case letters with initial upper-case letters. The letters
and the numerals used shall be Series E(M) of the "Standard Highway
Signs" book (see Section
1A.11). Other word legends shall be in capital letters. Interline
and edge spacing shall be as specified in Section
2E.14.
Lettering size on freeway and expressway signs shall be the same for both rural and urban conditions.
| Type of Sign | Type of Interchange (see Section 2E.29) | Overhead | |||
|---|---|---|---|---|---|
| Major | Intermediate | Minor | |||
| Category a | Category b | ||||
| A. Advance Guide, Exit Direction, and Overhead Guide Signs |  |
|
|
|
|
| Exit Plaque | |
|
|
|
|
| Word | 250 | 250 | 250 | 200 | 250 |
| Numeral & Letter | 375 | 375 | 375 | 300 | 375 |
| Interstate Route Sign | |
|
|
|
|
| Numeral | 450 | — | — | — | 450 |
| 1 or 2 Digit Shield | 900 x 900 | — | — | — | 900 x 900 |
| 3 Digit Shield | 1125 x 900 | — | — | — | 1125 x 900 |
| U.S. or State Route Sign | |
|
|
|
|
| Numeral | 450 | 450 | 450 | 300 | 450 |
| 1 or 2 Digit Shield | 900 x 900 | 900 x 900 | 900 x 900 | 600 x 600 | 900 x 900 |
| 3 Digit Shield | 1125 x 900 | 1125 x 900 | 1125 x 900 | 750 x 600 | 1125 x 900 |
| Alternate (Example: U.S. Alt. 56) | |
|
|
|
|
| Letters | 375 | 300 | 300 | 250 | 300 |
| Numeral | 450 | 375 | 375 | 300 | 375 |
| Cardinal Direction | |
|
|
|
|
| First Letter | 450 | 375 | 300 | 250 | 375 |
| Rest of Word | 375 | 300 | 250 | 200 | 300 |
| Name of Destination | |
|
|
|
|
| Upper-Case Letters | 500 | 400 | 330 | 265 | 400 |
| Lower-Case Letters | 375 | 300 | 250 | 200 | 300 |
| Distance Number | 450 | 375 | 300 | 250 | 375 |
| Distance Fraction | 300 | 250 | 250 | 200 | 250 |
| Distance Word | 300 | 250 | 250 | 200 | 250 |
| Action Message Word | 250 | 250 | 250 | 200 | 250 |
| B. Gore Signs | |
|
|
|
|
| Word | 250 | 250 | 250 | 200 | — |
| Numeral & Letter | 300 | 300 | 300 | 250 | — |
| Type of Sign | Type of Interchange (see Section 2E.29) | Overhead | |||
|---|---|---|---|---|---|
| Major | Intermediate | Minor | |||
| Category a | Category b | ||||
| A. Advance Guide, Exit Direction, and Overhead Guide Signs | |
|
|
|
|
| Exit Plaque | |
|
|
|
|
| Word | 10 | 10 | 10 | 8 | 10 |
| Numeral & Letter | 15 | 15 | 15 | 12 | 15 |
| Interstate Route Sign | |
|
|
|
|
| Numeral | 18 | — | — | — | 18 |
| 1 or 2 Digit Shield | 36 x 36 | — | — | — | 36 x 36 |
| 3 Digit Shield | 45 x 36 | — | — | — | 45 x 36 |
| U.S. or State Route Sign | |
|
|
|
|
| Numeral | 18 | 18 | 18 | 12 | 18 |
| 1 or 2 Digit Shield | 36 x 36 | 36 x 36 | 36 x 36 | 24 x 24 | 36 x 36 |
| 3 Digit Shield | 45 x 36 | 45 x 36 | 45 x 36 | 30 x 24 | 45 x 36 |
| Alternate (Example: U.S. Alt. 56) | |
|
|
|
|
| Letters | 15 | 12 | 12 | 10 | 12 |
| Numeral | 18 | 15 | 15 | 12 | 15 |
| Cardinal Direction | |
|
|
|
|
| First Letter | 18 | 15 | 12 | 10 | 15 |
| Rest of Word | 15 | 12 | 10 | 8 | 12 |
| Name of Destination | |
|
|
|
|
| Upper-Case Letters | 20 | 16 | 13.3 | 10.6 | 16 |
| Lower-Case Letters | 15 | 12 | 10 | 8 | 12 |
| Distance Number | 18 | 15 | 12 | 10 | 15 |
| Distance Fraction | 12 | 10 | 10 | 8 | 10 |
| Distance Word | 12 | 10 | 10 | 8 | 10 |
| Action Message Word | 10 | 10 | 10 | 8 | 10 |
| B. Gore Signs | |
|
|
|
|
| Word | 10 | 10 | 10 | 8 | — |
| Numeral & Letter | 12 | 12 | 12 | 10 | — |
| Type of Sign | Type of Interchange (see Section 2E.29) | Overhead | |||
|---|---|---|---|---|---|
| Major | Intermediate | Minor | |||
| Category a | Category b | ||||
| A. Advance Guide, Exit Direction, and Overhead Guide Signs | |
|
|
|
|
| Exit Plaque | |
|
|
|
|
| Word | 10 | 10 | 10 | 10 | 10 |
| Numeral & Letter | 15 | 15 | 15 | 15 | 15 |
| Interstate Route Sign | |
|
|
|
|
| Numeral | 24/18 | — | — | — | 18 |
| 1- or 2-Digit Shield | 48
x 48/ 36 x 36 |
— | — | — | 36 x 36 |
| 3-Digit Shield | 60
x 48/ 45 x 36 |
— | — | — | 45 x 36 |
| U.S. or State Route Sign | |
|
|
|
|
| Numeral | 24/18 | 18 | 18 | 12 | 18 |
| 1- or 2 -Digit Shield | 48
x 48/ 36 x 36 |
36 x 36 | 36 x 36 | 24 x 24 | 36 x 36 |
| 3-Digit Shield | 60
x 48/ 45 x 36 |
45 x 36 | 45 x 36 | 30 x 24 | 45 x 36 |
| Alternate (Example: U.S. Alt. 56) | |
|
|
|
|
| Letters | 15 | 15/12 | 12 | 10 | 12 |
| Numeral | 18 | 18/15 | 15 | 12 | 15 |
| Cardinal Direction | |
|
|
|
|
| First Letter | 18 | 15 | 15 | 10 | 15 |
| Rest of Word | 15 | 12 | 12 | 8 | 12 |
| Name of Destination | |
|
|
|
|
| Upper-Case Letters | 20 | 20 | 16 | 13.3 | 16 |
| Lower-Case Letters | 15 | 15 | 12 | 10 | 12 |
| Distance Number | 18 | 18/15 | 15 | 12 | 15 |
| Distance Fraction | 12 | 12/10 | 10 | 8 | 10 |
| Distance Word | 12 | 12/10 | 10 | 8 | 10 |
| Action Message Word | 12 | 12/10 | 10 | 8 | 10 |
| B. Gore Signs | |
|
|
|
|
| Word | 12 | 12 | 12 | 8 | — |
| Numeral &Letter | 15 | 15 | 15 | 10 | — |
Support:
Sign size is determined primarily in terms of the length of the
message and the size of the lettering necessary for proper legibility.
Letter style and height, and arrow design have been standardized
for freeway and expressway signs to assure uniform and effective
application.
Designs for upper-case, lower-case, and capital alphabets together with tables of recommended letter spacing, are shown in the "Standard Highway Signs" book.
Guidance:
Where upper- and lower-case lettering is used, the initial upper-case
letters should be approximately 1.33 times the "loop" height of
the lower-case letters. Freeway lettering sizes (see Tables 2E-3
and 2E-4) should be used when expressway geometric design is comparable
to freeway standards.
Other sign letter size requirements not specifically identified elsewhere in this Manual should be guided by these specifications. Abbreviations should be kept to a minimum.
Support:
A sign mounted over a particular roadway lane to which it applies
might have to be limited in horizontal dimension to the width of
the lane, so that another sign can be placed over an adjacent lane.
The necessity to maintain proper vertical clearance might also place
a further limitation on the size of the overhead sign and the legend
that can be accommodated.
Section 2E.14 lnterline and Edge Spacing
Guidance:
Interline spacing of upper-case letters should be approximately
three-fourths the average of upper-case letter heights in adjacent
lines of letters.
The spacings to the top and bottom borders should be equal to the average of the letter height of the adjacent line of letters. The lateral spacing to the vertical borders should be essentially the same as the height of the largest letter.
Section 2E.15 Sign Borders
Standard:
Signs shall have a border of the same color as the legend in order
to outline their distinctive shape and thereby give them easy recognition
and a finished appearance.
Guidance:
For guide signs larger than 3000 x 1800 mm (120 x 72 in), the border
should have a width of 50 mm (2 in). For smaller guide signs, a
border width of 31 mm (1.25 in) should be used, but the width should
not exceed the stroke width of the major lettering on the sign.
Corner radii of sign borders should be one-eighth of the minimum sign dimension on guide signs, except that the radii should not exceed 300 mm (12 in) on any sign.
Option:
The sign material in the area outside of the corner radius may be
trimmed.
