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FreightWaves Classics/Infrastructure: Slow down and pay attention to warning signs

Today is the first day of National Work Zone Awareness Week (NWZAW). In all 50 states and the District of Columbia, state departments of transportation and others are marking the week, hoping to raise the awareness of drivers as the spring road construction season begins. 

Over the past 100 years, roadway construction zone signage has become increasingly uniform. This is important, because in 2022 drivers of both cars and trucks pass through many local and state jurisdictions during their travels. 

Across the nation, advance warning signs are among the defining features of road construction and maintenance areas. For example the “Road Work Ahead” sign, which alerts drivers that they are approaching a work zone, is one of the familiar and easily identifiable temporary signs. These diamond-shaped fixtures are usually installed near work zones. 

This year's NWZAW signage. (Image:
This year’s NWZAW signage. (Image:

History of Road Work Ahead signs

The beginnings of the uniform Road Work Ahead advance warning sign – as well as other signs used in road work zones – go back to the 1920s. The Mississippi Valley Association of State Highway Departments (which is now known as the Mid America Association of State Transportation Officials) “appointed a committee to examine the viability of standardizing road signs” in 1922. At its 1923 annual meeting, the association approved the committee’s recommendations for a uniform system of signs.

A. H. Hinkle, the superintendent of maintenance for the Indiana State Highway Commission (a predecessor of the Indiana Department of Transportation) was one of the committee members. He wrote an article about the association’s push for uniform signs. The article was published in 1924 in Good Roads: The Journal of Highway Engineering and Transportation. Hinkle wrote that the association had “recognized the extreme necessity of standardizing [highway] signs.” He also made the point that consistency of signs used along the various roads in the United States was growing in importance. 

In his article Hinkle wrote, “The standardization of danger, warning and information signs on our highways is becoming more and more important each year due to the greater inter-county and inter-state traffic.” In regard to warning signs, Hinkle pointed out the association’s recommendation that they “should be uniform in all states.” He also reiterated the proposal that warning signs cautioning drivers to slow down should be diamond-shaped across the nation.

Warning signs continued to evolve over the next several decades. For example, the 1961 edition of the Manual on Traffic Control Devices for Streets and Highways (MUTCD) included a “new section that addressed more specifically than before recommendations for warning signs used for work zones.” The additional focus on warning signs can be attributed to the growth in highway construction projects across the nation. Construction of the Interstate Highway System was ongoing, and other state and national highways were being built or expanded. Further safety measures were needed to protect workers and drivers in the many construction zones. Among the guidelines in the 1961 manual was that warning signs be designed with black lettering on a yellow background.

Ten years later, the background color for “Road Work Ahead” and other construction zone warning signs was changed to orange. The 1978 edition of MUTCD reinforced the choice of orange as the background color for road construction and maintenance operations. It stated, “The high conspicuity of fluorescent orange colors provides an additional margin of safety by producing a high visual impact in hazardous areas.”  

Road Work Ahead and other warning signs designed to slow down traffic in work zones continue to help prevent accidents in those zones. This was highlighted in 1979 by Roxane Arnold in her Los Angeles Times article that focused on California Department of Transportation (Caltrans) road crews.

An old "WORKERS AHEAD sign. (Photo:
An old “WORKERS AHEAD” sign. (Photo:

“Usually, the first warning sign is posted about a mile before the work begins,” Arnold wrote. “A Caltrans truck with warning lights and arrows blinking furiously pulls to the shoulder of the road. Doors on each side open quickly and workers fall out to pull the bright ‘Road Work Ahead’ sign from the truck bed. The workmen are cautious as they place the warning close to the lane of oncoming traffic.”

Drivers, do yourself, your fellow motorists and those working on our nation’s roads a favor. Heed the roadway warning signs; slow down, pay attention and drive more safely. That’s good for you and everyone else on the road.

Road Work Ahead sign. (Photo:
Road Work Ahead sign.