San Francisco, Feb 6 (IANS): Tesla and SpaceX CEO Elon Musk has told Mayor of Miami city in the US that his Boring Company could dig a 3.2 km tunnel for just $30 million -- a fraction of the $1 billion cost quoted by local transit officials.

Musk told Mayor Francis Suarez that he could finish the job in six months which could otherwise take four years, reports The Verge.

Mayor Suarez shared the details in a video posted to Twitter.

"Musk is focused on trying to deliver a project that will have the maximum utility for our residents for the least amount of money. The order of magnitude in terms of savings is significant," he said in the video on Friday.

Digging under Miami is complex as it is built on limestone which is spongey.

This problem "also helped drive up the price of a tunnel under the Port of Miami, which was less than a mile but still cost around $700 million".

Musk first tweeted about wanting to tunnel under Miami on January 18.

"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," he posted.

"If Governor & Mayor want this done, we will do it."

The Boring Company is nearing completion of its first commercial service underneath the Las Vegas Convention Center.

The company is also in talks for a tunnel in San Bernardino County, California.