Sign and Poster Guidelines for the Forest Service
Chapter 3A Traffic Control Devices
All Roads
- 3A.1 Regulatory Signs
- 3A.2 Intersection Controls—STOP/YIELD Signs
- 3A.3 Speed Limit Signs
- 3A.4 Road Closures and Restrictions
- 3A.5 Commercial Use Permits and Other Restrictions
- 3A.6 Weight Limits
- 3A.7 Warning Signs
- 3A.7.1 Horizontal Alignment Signing
- 3A.7.2 Other Warning Signs
- 3A.7.2a ROAD NARROWS Sign
- 3A.7.2b Narrow, Rough, Steep, or Winding Road Signs
- 3A.7.2c ONE-LANE ROAD Sign
- 3A.7.2d Vehicular Traffic and Nonvehicular Signs
- 3A.7.2e STREAM CROSSING or FORD Signs
- 3A.7.2f IMPASSABLE DURING HIGH WATER and FLASH FLOOD AREA Signs
- 3A.7.2g CLOSED GATE XX FT or CLOSED GATE AHEAD Signs
- 3A.7.2h CATTLEGUARD XX FT or CATTLEGUARD AHEAD Signs
- 3A.7.2i NO TRAFFIC SIGNS Signs
- 3A.7.3 Coincident Routes
- 3A.7.4 Additional Warning Signs
- 3A.8 Markings
- 3A.9 Pavement Centerline Markings
- 3A.10 Guide Signs
- 3A.11 Feature Signing
- 3A.12 Miscellaneous Road Information Signs
- 3A.13 Scenic Byway Signing
3A.1 Regulatory Signs
Chapters 2B and 5B of the MUTCD contain guidelines for regulatory signs. Included here are those Forest Service guidelines that supplement the MUTCD or provide additional emphasis as needed for NFSRs.
Regulatory signs inform road users of traffic laws or regulations and indicate the applicability of legal requirements that are not apparent.
Regulatory signs for public and commercial use restrictions on NFSRs, such as weight, size, road closure, and speed limits shall be supported by law or a signed order. See FSH 7709.59, Transportation System Operations Handbook.
Regulatory sign sizes for conventional roads are shown in the MUTCD, Table 2B-1. Sign sizes for low-volume roads are shown in the MUTCD, Table 5A-1. NFSRs with speed limits or 85th percentile speeds of 35 miles per hour or less would require the minimum sizes. Oversized signs may be used when needed, based on an engineering judgment or engineering study for higher speeds or other situations requiring greater sign visibility. Table 3A-1 shows the sign sizes by road type for regulatory signs that are more commonly used on NFSRs.
3A.2 Intersection Controls—STOP/YIELD Signs
Intersections on NFSRs may appear different from those on other roads that drivers are accustomed to driving for several reasons:
- Intersections may not be signed.
- Grades are often steeper.
- Intersecting angles may be sharper.
- Road surfaces and conditions change frequently.
- Roadside vegetation may inhibit sight distance.
Many intersections on low-volume NFSRs do not need intersection control in the form of STOP or YIELD signs. Unwarranted installation of these signs causes unnecessary stops or delays. Place those signs only where there is a clear need and a plan to enforce the regulation. If there is no enforcement of regulatory signs, there is no consequence to drivers who ignore signs they consider unnecessary. If enforcement is not planned or feasible, do not install signs that contribute to the sign credibility problem. Unnecessary signs create a climate of disrespect for all signs and result in the possibility of accidents caused by drivers ignoring necessary signs.
R1-1
R1-2
Use a STOP sign only when traffic is ALWAYS required to stop. Consider using YIELD signs in lieu of STOP signs in many locations when appropriate. YIELD signs do not require drivers to come to a full stop. They still clearly establish right-of-way and do not require the level of enforcement needed for STOP signs.
When used, YIELD signs normally should be placed to control the traffic on the road with the lowest volume. They should not be placed on the approach to more than one of the intersecting roads at a "Y" or "T" intersection, nor placed on more than two approaches at an "X" intersection. They should not be used at any intersection where there are STOP signs.
3A.2.1 Where to Install STOP and YIELD Signs
Where traffic volume exceeds 400 SADT, use the MUTCD, Section 2B in performing an engineering study or engineering judgment evaluating the need for STOP or YIELD control at intersections.
With traffic volume less than 400 SADT, use the MUTCD, Section 2B and 5B in conjunction with the following information and Figure 3A-1 in performing an engineering study or engineering judgment about the need for STOP or YIELD control at intersections of low-volume roads.
Engineering judgment may be sufficient for a single-stop situation. Perform an engineering study for multi-way stops at an intersection.
Intersection control may not be needed when:
- Traffic volumes are less than 100 SADT on all approaches, unless a need
has been determined by engineering study or engineering judgment or demonstrated
by accident history.
- Approach speeds are equal to or less than 15 miles per hour.
Intersection control may be needed when:
- Adequate sight distance does not exist on all approaches to a low-volume
road intersection.
- Two low-volume roads with similar SADT intersect, and the application of
the right-of-way rule could be unduly hazardous.
- Two or more vehicle accidents have occurred within the last 3 years, or
an accident investigation indicates the need for intersection control.
- The intersection configuration is confusing, such as with "Y" intersections, and normal right-of-way expectations may be violated.
Re-evaluate intersection control needs when there is a change in use patterns, such as commercial or log haul or new recreation development.
Click on image for
larger view
Figure 3A-1 Sight Triangle
Obstruction
An obstruction in the sight triangle is anything
over 3.5 feet high. A few trees would not be considered
an obstruction if limbed up to 9 feet above the line of sight
and good sight of vehicles approaching is available.
*Obtain sight distances from Table 3A-2.
3A.2.2 Adequate Sight Distance
One of the primary considerations for choosing between a STOP and YIELD sign at an intersection on low-volume roads is adequate sight distance, and the driver’s ability to see all potentially conflicting traffic on the other legs of the triangle illustrated in Figure 3A-1. Evaluate sight distance triangles for all approaches to an intersection in an engineering judgment or engineering study.
Measure adequate sight distance as follows:
- Determine the approach speed for each approach to the intersection by using
the 85th percentile speed or a speed study. (See Section
3.9.3 of these Guidelines.) Where these methods are not readily available,
use the commonsense method of driving the road at various speeds to determine
a prudent speed for each approach.
- Use the approach speeds to determine the sight distance requirements for
each approach in accordance with the "no control" figures in Table
3A-2.
- On each approach, from the approach distance for its speed, measure the
distance from the intersection to where a vehicle on other approaches would
no longer be visible.
- Where those measured distances are longer than those in the "no control" columns
in Table 3A-2, no control is needed.
- Where those distances are less than "no control" distances but
more than "stop control" distances, consider using a YIELD sign.
- Where those distances are less than "stop control" distances, consider using a STOP sign.
3A.3 Speed Limit Signs
Impose speed limits only where and when necessary. Speed limits shall be authorized by law or an order following 36 CFR 261 and FSH 7109.59 and shall be enforced. The establishment of speed limits shall be based on engineering studies made in accordance with established traffic engineering practices.
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At least every 5 years, nonstatutory speed limits should be re-evaluated where significant roadway characteristics or surrounding land use has changed. Minimum posted speeds on NFSRs should not be less than 15 miles per hour.
3A.4 Road Closures and Restrictions
Travel by various types of traffic or vehicles on NFSRs may be restricted seasonally or yearlong to accomplish a variety of management strategies. Roads may also be closed to all types of traffic including foot and stock traffic for temporary emergencies or for special situations such as protection of a threatened or endangered species.
R13-1b
Use the ROAD CLOSED sign to mark roads that have been closed to all traffic except authorized vehicles. It is intended primarily for use where travel on the road has been impacted by situations such as work zones, incident zones, floods, landslides, and bridge washouts. Do not use at a gate or other restriction device for seasonal or long-term access and travel management road restrictions.
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Refer to Chapter 6, Travel Management, in these Guidelines for detailed information on displaying access and travel management decisions.
3A.4.1 Weed Free Restrictions
Use the WEED FREE sign at the entrance to areas where a weed free order has been issued. The last line of this sign may be modified to include the appropriate jurisdiction such as: ON NATIONAL FOREST LANDS or ON PUBLIC LANDS.
FR17-1
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