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       California transportation engineers are testing orange pavement paint to see if it can improve safety at construction sites. (California Department of Transportation)
       Southern California transportation engineers are trying to figure out whether using orange stripes in construction zones can help improve safety—a goal their counterparts across the country have been working on for more than a decade.
       During construction on a section of Interstate 5 north of San Diego, California engineers used orange road markings to create carpool lanes.
       The California Department of Transportation is using additional colors to highlight white and yellow lane markings during a highway widening project. On one side of the highway, white dashed lines frame orange lines like the edge of an Oreo cookie. On the other side, the California Department of Transportation is experimenting with a new design that divides the dashed lines vertically into two halves: half white and half orange.
       The state’s approach differs slightly from previous experiments with orange lane markings in Wisconsin, Texas and Kentucky, where highway departments used orange paint instead of the traditional white or yellow.
       ”I think the easiest way is to keep the original stripes and use orange as a contrast color,” said Brian Hadley, the California Department of Transportation engineer in charge of the project.
       Like many other states, California often uses black paint to make white stripes more visible, especially on concrete surfaces or east-west roads, as sunlight reflection can make the white stripes difficult to see.
       Governments have long sought to improve safety on construction sites. According to the National Security Council, 857 people were killed and 44,240 injured in construction accidents in 2020.
       Road maintenance workers often take various preventative measures to warn drivers about roadworks, including installing checkpoints, bollards, and flashing signs.
       However, Hadley noted that drivers pay particular attention to traffic lights on the road. He explained that this is one of the reasons why road signs on overpasses are so popular—so drivers know which lane leads to the highway they need.
       ”Personally, I find that when I’m driving, I’m more focused on the road than on the road signs,” he said.
       Engineers also found that improving road markings can reduce the number of accidents involving vehicles running off the road. He also noted that research in California shows that using red-backed reflective stripes on the road surface also helps reduce the number of oncoming vehicles.
       For example, during a major renovation of the Milwaukee Zoo overpass in Wisconsin, orange paint was used instead of white on some sections of the road.
       Although the new color hasn’t reduced the number of traffic accidents, it’s proving popular with drivers. A survey found that 80% of drivers surveyed said the orange color improved their perception of construction zones, and 83% found it more visible than white stripes.
       Wisconsin engineers also offered recommendations on the most effective colors and types of paint.
       In 2019, Kentucky began using orange lane markings on Interstate 75. The state also planned to paint 8-foot-tall letters on the road indicating a 55 mph speed limit. However, a project evaluation found that speed limits remained unchanged with both orange and white lane markings.
       The North Texas Tollway Agency also experimented with orange road markings. Preliminary results show that 61% of drivers surveyed said the orange markings improved their awareness of construction zones, and 88% of respondents expressed a desire to see this color in other construction zones throughout Texas.
       Transport authorities in Canada and New Zealand have also experimented with using orange paint on construction sites.
       In California, engineers will use video monitors to evaluate vehicle movement and equipment to track changes in paint gloss and reflectivity over time, thereby monitoring the effectiveness of selected color schemes.
       Hadley hopes these improvements will be significant enough to prompt the Federal Highway Administration and state officials to allow the use of orange as a contrasting color in future construction projects. However, this requires temporary exemptions from the federal Uniform Traffic Control Equipment Manual and its California counterpart.
       However, Hadley notes that such exceptions could be approved after a convincing court case, such as California’s approval to add red bus stripes on freeway ramps.
       Hadley said the department first received approval for the plan in 2020. Testing of the new road markings is expected to continue for about a year while construction work is underway.