“You see them where nothing else works because they’re generally more expensive,” Gettinger said.
Tunneling technology has progressed significantly in the last generation, he said. Pressure is applied at the face of the new tunnel, preventing water and earth from flooding the excavation site. This has made tunneling viable in more places, according to Gettinger.
But Florida’s dry land — and the lack thereof — brings unique challenges for tunnel builders.
Florida’s limestone can make it harder to optimize a tunneling machine because there are natural holes in it, Gettinger said. Tunnel builders prefer when rock is solid, he said. It’s easy to customize a machine for consistent conditions, like solid rock or soil. Climate change also adds risk for tunnels, due to sea levels rising and tunnels potentially flooding. In Malaysia, Gettinger said, tunnels have been specifically designed to manage flooding.
Florida has high levels of groundwater and gets more rainfall than most states.
Some of Florida’s limestone include underground aquifers, which need to be protected given potential impacts on groundwater, according to Greg Raines, global tunnel practice leader at Stantec. Sinkholes and settlement will also need to be controlled for in Florida, Raines said.
These kinds of complications could impact tunneling costs. Florida’s unique challenges would make it very difficult to estimate tunneling costs, Raines said. The Port of Miami tunnels, which is nearly a mile, cost $1.1 billion and took four years to build. Tunneling costs worldwide have ranged from $175 million per mile to $3.5 billion per mile, Raines said.
The Florida mayors declined to say if they would insist on any provisions in a contract related to cost overruns. The Boring Company did not respond to requests for comment for this story.
But the risks haven’t deterred Florida’s leaders, who see additional places tunnels might help.
Florida leaders are excited, and point to Musk’s successes. They aren’t expressing worry that the Boring Company could struggle with some of the unique challenges of tunneling in Florida.
“I see this as a revolutionary opportunity to rethink transportation in South Florida and other regions around the country,” Fort Lauderdale Mayor Dean Trantalis told CNN Business.
The mayor declined to reveal if the government would subsidize tickets, akin to public transportation, or if operating revenue would go to the government, or the Boring Company. A spokesperson said that discussions so far are preliminary.
Trantalis said that growing train traffic in his city risks worsening vehicle and ship traffic as they compete for space. He had wanted to build a tunnel for trains under a stretch of the city, but had been told by state officials that it was too expensive. But then Trantalis said he saw a recent Twitter exchange between Musk and Miami Mayor Francis Suarez, which inspired him to reach out to the Boring Company.
The train tunnel would need to be 24 feet in diameter, twice the size of The Boring Company’s existing tunnels. The wider a tunnel is, the more it costs to dig. Trantalis said he expects they’ll start on a simpler project, the two-mile tunnel to the beach. Fort Lauderdale and the Boring Company are currently studying the local geology to determine what path to take, Trantalis said. A contract hasn’t been signed yet, he said.
Trantalis said meeting the Boring Company has opened the city’s eyes to other opportunities, like using a tunnel network to alleviate on-street traffic.
Trantalis said the initial tunnel to the beach could carry hundreds of people per day. For comparison, that would mean it carries fewer riders than about half of Broward County Transit’s bus lines, which operate in Fort Lauderdale.
Gettinger, one of the tunneling experts, believes tunnels in US cities will become increasingly common as populations in big cities grow. The more expensive land is, the more it makes sense to utilize every square foot, whether for a train tunnel, car tunnel or sewage tunnel, he said.
No matter what comes next, Musk may not be using the tunnels much himself to visit Florida’s beaches. He’s said he only enjoys going to the beach for a few days.