What is that white residue in the Las Vegas airport connector tunnel?

If you’ve driven in the Airport Connector Tunnel, you’ve probably noticed drops of water falling on your windshield and a white residue on the ceiling of the tunnel and on the road, which is deteriorating in some areas.

The drops and residue have been caused by mineral deposits, also known as hard water buildups, seeping onto the roadway from a section of Harry Reid International Airport’s airfield that the tunnel passes under, according to Monika Bertaki, airport spokeswoman.

“This occurs over time when water trapped in soils above the tunnel seeps through the concrete and mixes with minerals,” Bertaki said in an email. “It’s not unusual in concrete structures and is not an indication of structural issues.”

The airport has taken steps to address the mineral deposits and is actively monitoring the situation.

“We recently completed a major airfield drainage improvement project last fall to build concrete drainage channels above the tunnel to minimize ground water,” Bertaki said.

The airport also carries out routine tunnel maintenance, which leads to overnight lane closures. During that time, crews also inspect the tunnel during maintenance periods to ensure it is structurally sound.

“The recent overnight closures of the airport connector tunnel are primarily for routine maintenance,” Bertaki said. “These activities are scheduled during off-peak hours to minimize traffic disruption and ensure the long-term safety and integrity of the tunnel — similar to how we maintain other critical infrastructure.”

Plans are also in place to address the road conditions inside the tunnel caused by the mineral deposits.

“Looking ahead, we plan to bid out a project for full roadway repavement inside the tunnel,” Bertaki said. “While this work is not directly part of the airport’s upcoming multimodal center or broader modernization projects, it does align with our goal of delivering a well-maintained and resilient infrastructure network that supports future growth and convenience for the public.”

Airport officials did not provide a projected timeline as to when the repaving of the airport tunnel roadway could take place.

The airport last year announced improvement plans, which included adding multimodal transit centers north and south of the airport and enhancing the tunnel, among other upgrades. The north multimodal center will feature ride-hailing pickup and drop-offs, parking and the potential for a Boring Co. Vegas Loop station to be built next to the airport facility to allow for connectivity to the Elon Musk-owned tunnel people mover system.

Contact Mick Akers at makers@reviewjournal.com or 702-387-2920. Follow @mickakers on X. Send questions and comments to roadwarrior@reviewjournal.com.