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Safety guides and audits to make your job as a safety professional easier

Work Zone Safety and Traffic Control


Safety in construction work zones is of great concern since it is one of the most hazardous occupations in the USA.

Workers are subjected to possible accidents from:

  • movement of equipment and vehicles within the work zones
  • hazards from general construction work
  • passing motor vehicles intruding in the work zone
  • flaggers and other construction workers being struck by vehicles or construction equipment
  • overturning vehicles and equipment
  • collision, or being caught in running the equipment and others

Protecting Workers from Vehicular Traffic

protecting workers

According to the Bureau of Labor Statistics (BLS), traffic zone workers are roughly as likely to be struck by construction- or maintenance-related equipment (dump trucks, bulldozers, graders, etc.) as by cars, vans, tractor-trailers, buses, and motorcycles. The BLS says between 2003 and 2010, U.S. workers were fatally struck 152 times by construction- or maintenance-related equipment and 153 times by the other vehicles.

Most of the fatalities are due to:

  • on-foot workers struck by passing vehicular traffic
  • on-foot workers struck by construction vehicles
  • construction vehicle operator and occupant events (e.g., rollovers)
  • highway traffic accidents caused by crashes involving motorists from the passing traffic that intrude into the work area

Key Engineering Controls and Work Practices

  • Develop and use a site plan that provides traffic flow details (See traffic flow diagrams. Other Manual on Uniform Traffic Control Devices (MUTCD) model plans are also available).
  • Use flaggers, traffic cones, and/or highway channeling devices to steer traffic away from response and recovery workers along the roadway.
  • Use flaggers, standard road signs (e.g., "work zone ahead"), or message boards to warn approaching vehicles of a work area.
  • Give motorists plenty of warning of upcoming work zones. Place the first warning signs at a distance calculated as 4 to 8 times (in feet) the speed limit (in MPH). Use a higher multiplier for higher speed areas (e.g., a 15 MPH road under construction should have its first warning sign at least 60 feet from the work zone, while a work zone needed in a 65 MPH zone should have its first sign approximately 520 feet away).
  • Ensure the work zone is well lit, but control glare to avoid temporarily blinding response and recovery workers or passing motorists.

High Visibility Safety Apparel and Headwear

Some vest colors provide better contrast.

ANSI/ISEA 107-2004 specifies four performance classes of apparel or headwear that have different amounts of reflective and background material to enhance pedestrian worker visibility under a variety of work and traffic conditions.

Employers should perform a hazard analysis to decide which performance class is needed based on the work conditions anticipated (e.g., closeness of the work area to traffic, time of day/night, weather, complexity of the background environment, pedestrian worker's task load (need to divert attention to complete other tasks), and traffic speed). This analysis is part of the PPE assessment required by 29 CFR 1910.132(d).

  • Class E garments are pants and shorts that have retroreflective and background materials, but may not meet minimum area or placement requirements outlined in the standard. Class E garments are not intended to be worn without a Class 2 or 3 garments
  • Class 1 garments provide the minimum amount of required material needed to tell the pedestrian worker apart from the work environment. Class 1 garments are appropriate for activities where pedestrian workers can pay full attention to the approaching traffic, there is enough separation between the pedestrian worker and the vehicle traffic, the work background is not complex, and vehicles and equipment are traveling at speeds less than 25 mph.
  • headware
    A sleeveless garment cannot be considered Class 3.
  • Class 2 garments are appropriate for most hurricane response and recovery work because of the complex work backgrounds, closeness of pedestrian worker to the traffic, the need for the pedestrian worker to divert his/her attention to complete other tasks, or vehicles/equipment are traveling at speeds of 25 miles per hour (mph) or more. Class 2 garments provide better visibility than Class 1 garments by providing additional coverage of the torso.
  • Class 3 garments offer the greatest level of visibility in both complex work backgrounds and through a full range of body motion. Class 3 garments should be considered for activities where a pedestrian worker may be exposed to higher vehicle speeds and/or reduced sight distances, the pedestrian worker and vehicle operators have high task loads, or the wearer must be identifiable as a person at least one-quarter mile away.

Traffic Control Within a Worksite

Make sure you follow these key engineering controls and work practices:

  • Develop and use a site plan that provides traffic flow details.
  • Limit access, barricade, or set up controlled access zones where the equipment will be used. For equipment that rotates and/or carries/dumps loads, create an access zone that extends beyond the maximum rotation/swing radius of the equipment and/or beyond the area where loads will be carried/dumped.
  • Illuminate the work area and its approaches to provide better visibility for drivers to safely travel through the work zone.
  • Establish/follow traffic control patterns (e.g., cones, barrels, barricades) in work areas.
  • Use spotters where visibility is limited.
  • Check out this short video by Caterpillar: Off Highway Trucks - Fatal Mistakes
    (Click to play video)
  • Do not drive in reverse gear with an obstructed rear view unless the vehicle has an audible alarm or a signaler is used.
  • Ensure that spotters and heavy equipment operators have communications equipment or agree on and use hand signals.
  • Workers and pedestrians should make eye contact with heavy equipment operators before proceeding near equipment or operating areas.
  • Use ANSI/ISEA 107-2004 compliant high visibility safety apparel and headwear.
  • Provide signaling, slow/stop signs, or wands/flashlights for flaggers providing traffic control outside the work zone.

Accident Summary


A worker was cutting concrete along the white center line on a four-lane highway. Orange reflective barrels closed the left lane to traffic, which was routed to a single lane from approximately 8 miles. To accommodate the worker, three to four barrels had been moved into the active traffic lane, and a flagger was slowing down traffic and directing it slightly onto the berm area. An approaching semi-tractor and trailer rig were exceeding the speed limit when the driver hit the guardrail and lost control of his vehicle. The tractor and trailer bounced back through the barrels and struck the worker from behind, killing him.


Loading, Transporting & Unloading Heavy Equipment - Iowa Department of Transportation. This video shows the special considerations involved with moving equipment too large to be self-transported over long distances. Emphasis is on visibility and respect for the size and weight of the equipment. With footage from operating work zones, good safety practices, actual safety hazards and unsafe working conditions and procedures are illustrated.


Before beginning this quiz, we highly recommend you review the module material. This quiz is designed to allow you to self-check your comprehension of the module content, but only focuses on key concepts and ideas.

Read each question carefully. Select the best answer, even if more than one answer seems possible. When done, click on the "Get Quiz Answers" button. If you do not answer all the questions, you will receive an error message.

Good luck!

1. A 15 MPH road should have its first warning sign _____ from the work zone.

2. Which of the following provide the minimum amount of required material needed to tell a pedestrian worker apart from the work environment?

3. Which of the following offer the greatest level of visibility in both complex work backgrounds and through a full range of body motion?

4. What should workers and pedestrians do before proceeding near heavy equipment or operating areas?

5. To give motorists plenty of warning of upcoming work zones, place the first warning signs at a distance calculated as _____.

Have a great day!

Important! You will receive an "error" message unless all questions are answered.