Control Traffic in Work Zones

Traffic control guidelines provide a clear plan for keep workers safe on the road.

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You may not spend as much time working in roadways as a highway construction worker, but work zones on streets and roadways are still dangerous places. There are many strategies that can help prevent workers and equipment being struck by passing cars.

The risks for highway construction workers are a bit different, of course. About half of the fatalities involve construction equipment rather than passing traffic. But there is a lot to be learned from an industry that strives to prevent the 100 deaths and 20,000 injuries that occur in work zones on the nation’s roads every year.

Because there are no published standards or regulations, the U.S. Department of Transportation developed Utility Work Zone Traffic Control Guidelines to help those working in temporary traffic work zones. The guidelines are intended for utility work, such as electric supply, gas, telephone, cable, sewer cleaning, grass cutting, tree trimming and landscaping work located in or around public thoroughfares, according to the DOT.

The dangers in these work zones vary, depending on such factors as:

  • Traffic volume
  • Travel speed
  • Distance of the work area from the travel lanes
  • Work duration
  • Sight distance and work area visibility

Best practices

Orange is the universal color for traffic work zones, and drivers have grown to recognize warning devices such as cones, signs, barricades, drums and oscillating lights on vehicles. Whatever is used, the work zone should be conspicuous to the driver and provide ample advance warning.

In the work zone itself, equipment and vehicles provide further warning for motorists and serve as an important barrier between the traffic and the workers. White is best for visibility, though orange trucks may be most obvious to drivers as being part of the work zone.

Amber lights are used by all state road agencies, and the DOT’s guidelines say amber is the desired color to indicate temporary work zones. While adding blue and red lights has been shown to be more effective in getting drivers to slow down, several states do not allow blue and red lights for nonemergency vehicles.

Arrows and flashing lights are more effective than rotating lights, according to the DOT. Arrow panels are recommended when work occupies a traffic lane.

Vehicle markings have been shown to increase visibility during the day and at night. “A rear-end marking treatment using black diagonal stripes mounted on an orange background has been shown to be most effective, followed by a pattern of alternative orange and white reflectorized blocks along the perimeter of the back of the truck,” according to DOT’s guidelines.

If the vehicle is parked on the shoulder, advance warning signs are necessary to make sure drivers are aware — from 100 feet in low-speed urban areas to 500 feet in rural locations. The document includes many examples of traffic control plans for various conditions, including effective placement of warning signs, vehicles and traffic tapering devices such as cones and barrels.

Travel lanes require at least 10 feet, though 9 feet is OK for low-volume traffic areas such as streets in residential areas. Parking workers’ personal vehicles across the street only serves to further restrict traffic and increase the chance of an accident, so they should park far enough away as to not add to the problem.

Workers should wear Class 2 or 3 high-visibility garments along with orange hard hats. As with all safety matters, training is critical to ensure workers understand the risks and how to minimize them.

The Utility Work Zone Traffic Control Guidelines can be accessed at Training material, developed as part of the Federal Highway Administration’s Work Zone Safety Grant Program, is also available at


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