Caltrans Orange Stripes: The I-5 Experiment to Boost Construction Zone Safety

Drivers cruising along I-5 in northern San Diego County may have noticed something odd: the usual white lane lines… paired with bright orange ones. No, it’s not a mistake. It’s part of a Caltrans experiment to make construction zones more obvious — and the early results say it’s actually doing the job.

According to Caltrans, about 83% of drivers who passed through the orange-striped section said they were more aware they were in a construction zone. Most people didn’t even know what the orange stripes officially meant — they just knew it felt “different,” and different tends to make people pay attention. Nearly three-quarters slowed down, and about the same number said the lines were easier to see at night.

Not bad for a simple color change.

Traditionally, the U.S. only uses white and yellow lane markings. But orange immediately screams construction, and having it painted directly next to the usual stripes creates a contrast that’s hard to ignore. It also fixes a common headache: leftover markings from old lane setups that confuse both humans and driver-assist systems. The orange basically says, “Follow this line. Ignore the ghost ones.”

Other states have tried this, too

California isn’t the first to test orange lane markings. Kentucky experimented with orange paint back in 2019, laying it right over white and yellow lines. Crash numbers ticked up slightly, but injuries went down — a sign that people were driving more cautiously.

Milwaukee used orange so it would be easier to spot on snowy, salt-covered roads. It worked during the day, but the lines nearly vanished at dusk and at night, which wasn’t ideal.

California seems to have learned from that. Instead of replacing the white lines, it’s pairing them with orange ones — boosting visibility without losing contrast at night.

What California is testing now

On this four-mile stretch of I-5:

• Southbound drivers see a single orange stripe painted just ahead of the standard white line.

• Northbound drivers get two orange stripes with the white one in the middle — basically a creamsicle Oreo of lane markings.

So far, I-5 near San Diego is the only place you’ll spot them. But with the pilot showing real safety benefits, Californians may start seeing these candy-colored stripes pop up in more construction zones across the state.