Flagstaff “Dark Skies” Project: ADOT Installs Amber LED Lights to Protect Night Sky

The Arizona Department of Transportation (ADOT) announced yesterday that crews have completed installing special amber LED lights at Interstate 40 interchanges in Flagstaff. The project, part of ADOT’s broader effort to improve safety while preserving the area’s world famous dark night skies, introduces an innovative lighting design that simultaneously illuminates highway areas for drivers and minimizes light pollution that might disrupt stargazing and astronomical research. The new fixtures produce an amber glow instead of the harsh white light emitted by conventional LEDs. This “dark skies” approach was developed in consultation with local experts to ensure that highway safety and the region’s astronomical heritage can coexist.

According to the news release, the project involved installing more than two hundred amber LED light fixtures at interchanges along I 40 in Flagstaff and the west Flagstaff interchange on Interstate 17. ADOT engineers worked closely with the Flagstaff Dark Skies Coalition to select a light spectrum that provides adequate visibility for motorists while reducing glare and skyglow that could obscure the stars. Amber LEDs operate at a lower color temperature, producing less blue light that scatters into the atmosphere. Installing these lights required complex planning because the equipment is not standard on most highways, and the team had to retrofit existing poles and electrical infrastructure.

ADOT officials said they used special shielding and directional fixtures to keep the light focused on the roadway and out of the sky. Caroline Mandle, ADOT’s assistant director for operations and maintenance, explained in the news release that the project illustrates how infrastructure improvements can balance safety and environmental stewardship. She said that ADOT wants to “honor the dark skies initiative that makes Flagstaff unique” while maintaining safe roadways. The Dark Skies Coalition’s president, James Barlow, commended the collaboration, noting that it “demonstrates that transportation needs and dark sky protection are not mutually exclusive.” The coalition had previously partnered with ADOT to pilot these amber lights on the US 180 corridor, and the success of that pilot paved the way for the larger project.

This upgrade is part of ADOT’s ongoing commitment to sustainable transportation infrastructure. Officials said the amber LEDs not only reduce light pollution but also use less energy and last longer than traditional lights, providing long term savings for taxpayers. The project also aligns with Flagstaff’s community values; the city has long embraced dark sky policies to protect the nearby Lowell Observatory and attract visitors for stargazing. With the new lighting in place, residents and visitors can look forward to safer night driving and continued enjoyment of the region’s spectacular night sky. ADOT said it will continue monitoring the performance of the amber LEDs and share lessons learned with other jurisdictions considering similar upgrades. The agency’s news release underscores that thoughtful infrastructure design can support both safety and environmental goals.