PHOENIX – With transportation funding limited, a simple yet highly effective way to protect Arizona’s $20 billion-plus investment in state highways is sealing road surfaces against the ravages of weather, heavy use and time.

To help the Arizona Department of Transportation expand this preventive maintenance, Governor Doug Ducey’s executive budget for fiscal 2019 includes $25.6 million for pavement treatments known as fog seals and chip seals. This would be added to the $15 million ADOT currently has programmed for such work.

The funding would allow ADOT to address approximately 3,000 lane miles, 14 percent of all lane miles in the state highway system, with surface treatments to extend the life of pavement along many higher-volume routes.

“Highway maintenance is very much a case of pay now or pay more later,” said Dallas Hammit, ADOT’s state engineer and deputy director for transportation. “The requested funding would be used to prolong the life of pavement and reduce the need for more costly repairs later due to deterioration.”

ADOT has identified 132 highway stretches as needing surface treatment projects that have yet to be funded. While specific funding decisions would come later, these areas include – but aren’t limited to – interstates 8, 10, 19 and 40, state routes 85, 87 and 260, and US 93 and US 95.

It costs $3,000 per lane mile for a fog seal, which applies a diluted asphalt emulsion to the road surface. Chip sealing, a more involved and lasting treatment mixing gravel or similar material with liquid asphalt, costs $36,000 per lane mile.

Once pavement deteriorates, it costs $300,000 per lane mile to mill down and replace the asphalt surface. Replacing pavement in its entirety is far more expensive. For example, ADOT has invested $34 million in an ongoing project to rebuild 5 miles of Interstate 40 from the ground up in each direction west of Williams, a stretch that sees scores of freeze-thaw cycles each year along with regular snow and snowplowing.

With paved surfaces the main asset in Arizona’s overall transportation system, federal funding for preventive maintenance has been insufficient for ADOT to follow the recommended schedule for preserving taxpayers’ investment in state highways. As a result, maintenance work is becoming increasingly reactive and will fail to maximize the life expectancy of pavement.

“While Arizona’s transportation system remains one of the nation’s best, this request looks to the future,” Hammit said. “If we don’t adequately fund this essential maintenance, pavement will deteriorate faster than it would otherwise, leading to more expensive reconstructions in the long run.”