Sign and Poster Guidelines for the Forest Service
Chapter 3C Traffic Control Devices
Placement and Installation
- 3C.1 Introduction
- 3C.2 Sign Placement
- 3C.3 Marker Placement
- 3C.4 Sign Installation
- 3C.5 Installation Date and Vandal Warning Labels
- 3C.6 Other References
3C.1 Introduction
Uniform sign placement and installation assists drivers in observing signs and in determining where the directed action is to take place. Select locations that maximize the opportunity for signs to be visible and to convey the intended message.
When placing Forest Service signs on roads under other jurisdiction, coordinate signing requirements with that agency. In those instances, follow the placement and installation guidelines and standards of the agency with jurisdiction of the road.
3C.2 Sign Placement
Placement involves the horizontal positioning, vertical height, and location along the roadway where the sign is placed.
With the exception of the No Passing pennant, place all signs on the right-hand side of the traveled way as close to the standard location as is practical.
Consider the following guidelines when selecting sign placement locations:
- Place signs where they provide adequate time for proper viewer response,
considering factors such as speed, road conditions, intermediate intersections,
and road geometry.
- Select locations that minimize viewing obstructions. Some common placement locations to be avoided include:
- Dips in the roadway or trail.
- Just beyond the crest of a hill.
- Where a sign could be obscured by other signs.
- Where the sign may interfere with the normal operation of
the facility.
- Where there is increased need for drivers to focus on the
roadway.
- Too close to trees or other foliage that could grow to cover
the sign face.
- Snow removal areas.
- Erect signs individually on separate posts or mountings except where one sign supplements another, such as a warning sign with an advisory speed plaque, or where route markers and destination signs must be grouped.
3C.2.1 Sign Spreading
Several signs at the same location can overload road users with too much information, causing confusion and detracting from critical messages. Signs requiring different decisions by the road user shall be spaced sufficiently far apart for the required decisions to be made independently.
The following should be used as placement order:
- Location-critical regulatory signs such as STOP and YIELD
- Location-critical warning signs such as TURN and FLOOD HAZARD
- Other regulatory signs such as SPEED LIMIT
- Other warning signs such as LIVESTOCK and DEAD END
- Route markers
- Destination and other guide signs
- Informational and Motorist Services signs
The posted or 85th-percentile speed should be considered when determining the appropriate spread distance between signs.
On low-speed roads of 35 miles per hour and less, the minimum spread distance (in feet) between signs should be at least three times the average or posted travel speed (in miles per hour).
On higher speed roads of 40 miles per hour and greater, the spread distance (in feet) between signs should be at least 5 times the travel speed (in miles per hour).
3C.2.2 Longitudinal Placement
All signs need to be visible to drivers in time for them to see the sign, perceive the message, react, and complete the necessary maneuver considering approach speeds and road conditions.
Place regulatory signs at or near where their mandate or prohibition applies or begins.
Warning signs are normally placed in advance of the situation to which they call attention to allow adequate time for proper driver response. Table 3C-1 lists the advance placement approach distances for warning, STOP, or YIELD signs based on wet pavement or gravel on low-volume roads with 24-inch signs with 4-inch legends.
On paved roads with more than 400 AADT, use the MUTCD
Table 2C-4, which is based on larger signs. Table 3C-2 lists the advance placement distances for guide signs prior to junctions and intersections.
Place destination signs in advance of the point where the vehicle maneuvers should begin. Use advance placement distances in Table 3C-2 as the advance placement distance before the intersection.
Destination signs and route markers used to provide reassurance on major roads should be placed between 25 feet and 200 feet beyond the intersection on unpaved roads and approximately 300 feet beyond the intersection on paved roads.
3C.2.3 Clear Zones
No discussion for sign placement would be complete without an explanation of clear zones. Clear zones are the total roadside border area, starting at the edge of the traveled way, that is available for an errant driver to stop or regain control of a vehicle. This area might consist of a shoulder, a recoverable slope, and/or a nonrecoverable, traversable slope with a clear run-out area at its toe. Slopes steeper than 1V:3H are usually considered nonrecoverable.
High-speed, high-volume, paved highway clear zone guidelines are contained in AASHTO's Roadside Design Guide, 2002 edition. Widths ranging from 7 feet to over 40 feet are discussed, depending on the speed and volume of traffic.
AASHTO's Guidelines for Geometric Design of Very Low-Volume Roads (ADT<= 400), 2001 edition, notes it generally is not cost-effective to provide clear zones on very low-volume roads, particularly unpaved roads. However, clear zones of any width contribute to safety and should be provided and used where practical.
Sign placement on NFSRs shall follow breakaway or crashworthy guidelines for signs within roadway clear zones as required. Breakaway and crashworthy sign posts are defined in Section 3C.4.2.
3C.2.4 Lateral Placement
Lateral clearance for all sign placements is the distance from the edge of the traveled way to the nearest edge of the sign-not the post.
Lateral sign placement guidelines are:
- On higher speed roads with shoulders, a minimum of 6 feet lateral clearance
from the edge of the shoulder, or, if no shoulder, from the edge of the pavement,
should be used where roadway slopes permit.
- On all roads where signs are placed behind barriers such as curbs or guardrails,
a lateral clearance of not less than 2 feet from the roadside edge of the
barrier may be used.
- On low-volume roads with no shoulders, a minimum of 6 feet lateral clearance
should be used where roadway slopes and vegetation permit.
- On low-volume roads where roadside features, such as terrain, shrubbery,
and/or trees prevent standard lateral placement, a lateral clearance of not
less than 2 feet from the edge of the roadway to the roadside edge of the
sign may be used.
- Major sign installations, such as forest boundary signs on rock bases, should be located behind existing roadside barriers or outside of the clear zone. If a sign installation is located within the clear zone, a breakaway structure shall be used.
Figure 3C-1 shows the lateral placement of regulatory and warning signs and Figure 3C-2 shows the lateral placement for guide signs.
Figure 3C-1—Lateral and mounting height for regulatory and warning signs.
Figure 3C-2-Lateral placement and mounting height for guide signs.
3C.2.5 Mounting Height
Signs in rural areas shall be mounted at least 5 feet from the bottom of the main (or primary) sign from the elevation of the nearest edge of the roadway. Where parking or pedestrian movements occur, such as urban, business, commercial or residential areas, the clearance to the bottom of the main sign shall be at least 7 feet. Supplemental plaques or signs mounted below the main or primary sign may be 1 foot less than the specified heights. If the supplemental plaque or sign is greater than 1 foot in height, the primary sign must be mounted at a higher height to meet the minimum requirements for the supplemental sign.
On low-volume roads, a lateral offset of not less than 2 feet from the roadway edge to the roadside edge of a sign may be used where roadside features, such as terrain, shrubbery, and or trees, prevent standard lateral placement.
Figure 3C-1 shows the guidelines for mounting height for regulatory and warning signs. Figure 3C-2 shows guidelines for guide signs. Note that the 6-foot minimum is measured from the road edge for roads without shoulders and from the edge of the shoulder on roads with shoulders.
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