Mr Musk, who also founded the Boring Company, tweeted earlier this week that he had spoken to Florida’s governor, Ron DeSantis about his organisation digging the tunnels under Miami, Florida, which was recently named one of the most congested cities in the US in 2020.
“Cars and trucks stuck in traffic generate megatons of toxic gases and particulate, but Boring Company road tunnels under Miami would solve traffic and be an example to the world,” he later tweeted on Monday.
“If governor and mayor want this done, we will do it,” he added, while the mayor of Miami, Francis Suarez, a Republican, called the idea a “no brainer” and said: “we would love to be the prototype city.”
Mr Suarez, who has recently been pushing for members of the tech industry to move to Miami, also praised the idea on Thursday, saying: “Elon Musk is a person who has an amazing brand as well as his companies. He is an innovator.”
Cars & trucks stuck in traffic generate megatons of toxic gases & particulate, but @boringcompany road tunnels under Miami would solve traffic & be an example to the world.
Spoke with @RonDeSantisFL about tunnels last week. If Governor & Mayor want this done, we will do it.
— Elon Musk (@elonmusk) January 18, 2021
The proposal received an enthusiastic response from other local officials, including the Miami-Dade Democratic mayor, Daniella Levine Cava, and Florida’s Republican chief financial officer, Jimmy Patronis.
However, several local residents expressed confusion at the idea, as the city is situated only a few feet above sea level and is vulnerable in regards to rising sea levels.
Florida is also situated on a porous limestone plateau that is prone to flooding and sinkholes, which appear suddenly after erosion underground, according to AFP.
Kurtis Gurley, a professor of structural engineering at the University of Florida, told CBS Miami: “It doesn’t seem very smart and it is certainly going to be expensive.”
Mr Gurley added that the project would face challenges keeping water out of the tunnels while trying to shore up the walls during construction.
Others mocked the idea, as NPR reporter Wilkine Brutus tweeted: “Aquaman must be the project manager”.
Aquaman must be the project manager.
— Wilkine Brutus (@wilkinebrutus) January 19, 2021
While Politico reporter Michael Grunwald wrote: “This is probably the most important and innovative human being alive today but somebody ought to explain the geology of Florida to him before some incredibly stupid s**t happens.”
Despite the concerns, Michael Mooney, a professor of underground construction and tunneling at the Colorado School of Mines, told CBS construction of tunnels for transit under Miami would be possible.
He said tunnelling through limestone is common and added that although rising sea levels could put pressure on the construction, accommodations for that can be included in the design.
It would also not be the first road tunnel built in the area, as engineers completed construction of the 4,200-foot long Port of Miami Tunnel in 2014, which cost around $668.5m (£489.7m). There is not yet any information on how Musk’s proposal would compare.
In 2018, The Boring Company completed a one-mile, test tunnel in Hawthorne, California, costing around $10m (£7.3m), but it has not undergone large-scale construction of that type anywhere else in the US.