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Signs, Signals, and Barricades

Highway, road, street, bridge, tunnel, utility, and other workers for the highway infrastructure are exposed to hazards from outside and inside the work zone. Falls, electrical, struck-by, and caught between are the common hazards found in this type of work. Guidance for the set-up of work zone signs, barricades, flagging, etc. are found in the U.S. Department of Transportation's "Manual on Uniform Traffic Control Devices MUTCD (PDF)." The MUTCD is referenced in 1926 Subpart G. OSHA also provides guidance on it's Highway Work Zones and Signs, Signals, and Barricades webpage.

Signs for Construction

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OSHA Danger Sign.

Signs are the warnings of hazard, temporarily or permanently affixed or placed, at locations where hazards exist.

Signs convey both general and specific messages by means of words or symbols and must be visible at all times when work is being performed, and must be removed or covered promptly when the hazards no longer exist.

Danger signs

Danger signs must be used only where an immediate hazard exists, and must follow the specifications illustrated in Figure 1 of ANSI Z35.1-1968 or in Figures 1 to 13 of ANSI Z535.2-2011, incorporated by reference in 1926.6.

Danger signs must have red as the predominating color for the upper panel; black outline on the borders; and a white lower panel for additional sign wording.

Caution signs

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OSHA Caution Sign.

Caution signs must be used only to warn against potential hazards or to caution against unsafe practices. They must follow the specifications illustrated in Figure 4 of ANSI Z35.1-1968 or in Figures 1 to 13 of ANSI Z535.2-2011, incorporated by reference in 1926.6.

Caution signs must have yellow as the predominating color; black upper panel and borders: yellow lettering of "caution" on the black panel; and the lower yellow panel for additional sign wording. Black lettering must be used for additional wording.

The standard color of the background must be yellow; and the panel, black with yellow letters. Any letters used against the yellow background must be black. The colors must be those of opaque glossy samples as specified in Table 1 of ANSI Z53.1-1967 or in Table 1 of ANSI Z535.1-2006(R2011), incorporated by reference in 1926.6.

1. Which of the following is TRUE regarding the use of danger signs?

a. They must be used only where an immediate hazard exists
b. They are used only to warn against potential hazards
c. They are used to give notice of an imminent danger condition
d. They have a black upper panel and yellow lettering

Next Section

Signs in Construction (Continued)

Exit Signs

Exit signs, when required, must be lettered in legible red letters, not less than 6 inches high, on a white field and the principal stroke of the letters must be at least three-fourths inch in width.

Safety instruction signs

Safety instruction signs, when used, must be white with green upper panel with white letters to convey the principal message. Any additional wording on the sign must be black letters on the white background.

Directional signs

Directional signs, other than automotive traffic signs specified in paragraph (g) of this section, must be white with a black panel and a white directional symbol. Any additional wording on the sign must be black letters on the white background.

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OSHA Directional Sign.
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OSHA Instruction Sign.
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OSHA Exit Sign.

2. Which type of sign must be lettered in legible red letters?

a. Danger sign
b. Instruction sign
c. Exit sign
d. Directional sign

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Signs in Construction (Continued)

Traffic control signs and devices

At points of hazard, construction areas must be posted with legible traffic control signs and protected by traffic control devices.

The design and use of all traffic control devices, including signs, signals, markings, barricades, and other devices, for protection of construction workers must conform to Part 6 of the Manual on Uniform Traffic Control Devices for Streets and Highways (MUTCD) (incorporated by reference, see 1926.6).

Accident prevention tags

Tags are temporary signs, usually attached to a piece of equipment or part of a structure, to warn of existing or immediate hazards. They are used only until the identified hazard is eliminated or the hazardous operation is completed.

Accident prevention tags must be used as a temporary means of warning employees of an existing hazard, such as defective tools, equipment, etc. They must not be used in place of, or as a substitute for, accident prevention signs.

For accident prevention tags, employers must follow specifications that are similar to those in Figures 1 to 4 of ANSI Z35.2-1968 or Figures 1 to 8 of ANSI Z535.5-2011, incorporated by reference in 1926.6.

3. Accident prevention tags _____.

a. must be written in English
b. warn employees of existing hazards
c. may be used permanently
d. may be used instead of a sign

Next Section


Signals are moving signs, provided by workers, such as flaggers, spotters, and crane/hoist signal persons. They are also provided devices, such as flashing lights, to warn of possible or existing hazards.


Flaggers protect workers by providing temporary traffic control (TTC) and maintaining traffic flow through a work zone, despite a shutdown of lanes. They stop motorists from accidentally driving into the work area. Signaling by flaggers and the use of flaggers, including warning garments worn by flaggers, must conform to Part 6 of the MUTCD (incorporated by reference, see 1926.6).


Spotters have a different job than flaggers. They keep equipment operators in the work zone with obstructed views from backing over or running over workers they can't see. Spotters are also used when working in rough terrain areas, when performing blind lifts and when working around overhead power lines.

Crane and Hoist Signal Persons

Signal persons are used during crane and hoist operations to transmit signals to the operator. Only one person may give signals to a crane/derrick operator at a time, though any person may give an emergency stop signal. A more complete set of signals can be found in OSHA 1926 Subpart CC App A.

Work Zone Signals
Crane/Hoist Signal Person
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Work Zone Signals
Spotter signals
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Work Zone Signals
Flagger Signals
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4. Who keeps equipment operators from backing over workers or hitting objects?

a. Coworkers
b. Flaggers
c. Spotters
d. Crane/Hoist signal person

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Channelizing Devices

Traffic safety cones are the most common devices used to channelize traffic, divide opposing traffic lanes, divide traffic lanes when two or more lanes are kept open in the same direction, and delineate short-duration maintenance and utility work. The minimum cone size is 18 inches tall. For speeds of 45 mph or higher, or during nighttime operations, cones must be a minimum of 28 inches tall, and have retroreflective bands.

Tubular markers having a uniform diameter and at any height, should only be used where space restrictions do not allow for other more dominate devices. Tubular markers may be used to divide opposing traffic lanes, divide open lanes in the same direction on low speed roads and to delineate the edge of a pavement drop off.

Tall Channelizing devices are a minimum of 42 inches tall, using a tapered cone type shape and are a good option for use on high speed roadways in lieu of 28 inch cones due to their greater visibility.

Traffic safety drums are 36 inches tall and are the most dominant and preferred device for multi-lane high volume highways because they have the greatest visibility.

Vertical flat panel devices and devices with directional stripe patterns are not allowed due to frequency of placement errors.

Traffic Safety Drums or Tall Channelization Devices should be used for lane closure tapers on multi-lane highways with posted speeds of 45 mph or greater. If Tall Channelization Devices are used, using half the maximum spacing to increase the taper visibility is required. Traffic Engineer approval is required to use cones for this condition.

Work Zone Signals
Tall Cone and Tubular Markers
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Work Zone Signals
Safety Cone and Tubular Marker
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Work Zone Signals
Traffic Safety Drum
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5. Which of the following would be the best choice for use on multi-lane highways?

a. Traffic safety cones
b. Tubular markers
c. Traffic Safety Drums
d. Vertical flat panel devices

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A barricade is an obstruction to deter the passage of persons or vehicles.

Barriers in construction are one of the most important ways to protect workers but also the general public.

The design of barricades for protection of employees must conform to Part VI of the Manual on Uniform Traffic Control Devices are incorporated by reference in 1926.200(g)(2). Barriers should be designed such that they are easily visible and distinguishable as a safety device.

Generally used for road or ramp closures along with other channelizing devices and appropriate signing. Barricades used in work zone applications are portable devices with three primary types:

  1. Type 1 Barricade – Used on lower speed roads and streets to mark a specific hazard, or can be used for sidewalk closures as appropriate. The Type I Barricade usually has only one reflective rail. Typically it is at least 24 inches wide with orange and white stripes alternating at a 45 degree angle.
  2. Type 2 Barricade – Used on higher speed roadways and has more reflective area for nighttime use to mark a specific hazard. Type II Barricades have two reflective rails, also with alternating orange and white stripes.
  3. Type 3 Barricade – Used for road closures. Type III Barricades are larger and have ( use guessed it) three reflective panels with alternating orange and white stripes. They are at least 4 feet wide (or larger).
Type 3 Barricade
Type 3 Barricade
Type 2 Barricade
Type 2 Barricade
Mrschimpf / CC BY-SA
Type 1 Barricade
Type 1 Barricade

6. Which type of barricade would be best for road closures?

a. Type 1
b. Type 2
c. Type 3
d. Type 4

Check your Work

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Watch this video on flagging operations and procedures by the Minnesota Department of Transportation (MnDOT).

Final Exam