Billionaire-entrepreneur Elon Musk, who confirmed he was venturing into underground construction earlier this year, has started the construction of the first of what he says will be many tunnels in Los Angeles, California.
In late-2016, Elon Musk, the founder of SpaceX and Tesla Inc, established a new entity, The Boring Company, following statements on social media bemoaning the congested state of traffic in Los Angeles, California. On 18 December 2016, he tweeted “Traffic is driving me nuts. Am going to build a tunnel boring machine and just start digging…”
In April 2017, when images of a tunnel boring machine (TBM) emblazoned with a company name – The Boring Company – were posted on a SpaceX employees social media page, it all but confirmed Mr Musk’s comments were more than hyperbole. Then, during a TED talk soon after, Mr Musk released his vision for the future: an intricate series of underground tunnels facilitating the transportation of vehicles, goods and/or people, via an ‘electric skate’ which could reach speeds of more than 200 km per hour.
“We’re trying to dig a hole under LA. This is to create the beginning of what will hopefully be a 3D network of tunnels to alleviate congestion. You can go much further down than you can go up; the deepest mines are much deeper than the tallest buildings are tall,” he says.
“You can alleviate any arbitrary level of open congestion with a 3D tunnel network. A key rebuttal to tunnels is that if you add one layer of tunnels then that will simply alleviate congestion, it will get used up, and then you’ll be back where you started, back with congestion. But you can go to any arbitrary number of tunnels, and number of levels.”
The Boring Company’s website has since revealed more details of its plan, including steps to reduce the cost of tunnel boring, the development of an electric engine to power TBMs, as well as investigating technology that would recycle the earth displaced during tunnelling process to be repurposed in the manufacture of bricks.
Cheaper, faster, better
For Mr Musk and The Boring Company’s goal to become a reality, the affordability of TBM construction is the priority. The Boring Company says that digging fast and cheap tunnels could make the addition of Hyperloop viable. This would allow for travel at speeds of more than 1,000 km per hour, cutting down the journey from New York to Washington D.C. to less than 30 minutes.
According to Mr Musk, “The LA subway extension, which I think is a 2.5 mile (4 km) extension, was just completed for US$2 billion, so it’s roughly US$1 billion a mile…and this is not the highest utility subway in the world. I think we need to have at least a 10-fold improvement in the cost per mile of tunnelling.”
The Tunnel Boring Company’s first step to making TBMs cheaper is to reduce the tunnel diameter from the 8.5 m required for one lane of traffic, to the less than 4.5 m required for the stabilised electric sled, slashing tunnelling costs by as much as
3-4 four times. In addition to allowing it to reduce the diameter of its tunnels, the electric sled also allows for increased safety and speed, multiple payloads and eliminates emissions.
“According to regulations, a single road lane tunnel has to be 8-8.5 m in diameter to allow for crashes and emergency vehicles and sufficient ventilation for combustion engine cars. But if you shrink that diameter to what we’re attempting – which is 3.6 m (plenty to get an electric skate through) – you drop the diameter by a factor of two and the cross-sectional area by four, and the tunnelling cost scales with the cross-sectional area,” says Mr Musk.
Areas for improvement
The second step in The Boring Company’s manifesto is to increase the speed of the soft soil TBM, which it says is 14 times slower than a snail. It says there are a number of areas for development to reach the goal, including:
- Increasing power – the power output of a TBM can be tripled when combined with an upgrade to cooling systems
- Continuous tunnelling – existing technology can be modified for continuous tunnelling
- Automation – large machines require human operation; the addition of automation would improve safety and efficiency
- Electric power – the introduction of electric vehicles to replace diesel locomotives
- Research and development – there is a lack of US investment in research and development into tunnelling.
“Tunnelling machines currently tunnel for half the time, then they stop and then the rest of the time is taken up by putting in reinforcements for the tunnel wall. So, if you design a machine to do continuous tunnelling and reinforcing instead, that’ll give you a factor of two improvement. Combine that with the reduction of diameter, and it’s a reduction of a factor of eight,” says Mr Musk.
“Also, these machines are far from being at their power or thermal limits, so you can jack up the power to the machine substantially; I think you can at least get a factor of two, maybe a factor of four or five improvement on top of that. So, I think there’s a fairly straightforward set of steps to get somewhere in excess of an order of magnitude improvement in a cost per mile.”
Realising the vision
In mid-May 2017, Mr Musk posted more information on the progress of the project revealing that the entry hole, staging area and starting tunnel for a TBM – named Godot – had been completed. Godot’s segments had also been lowered into the starter tunnel and were going through final assembly. The first tunnel will run from Los Angeles International Airport (LAX) to Culvert City, Santa Monica, Westwood and Sherman Oaks. The 18 km journey from LAX to Westwood, facilitated by an electric sled switching between tunnels, would reduce travel time to 5 minutes. Mr Musk says he has plans for future tunnels, which will eventually cover all of greater Los Angeles.
This article was featured in the Summer edition of Trenchless International. To view the magazine on your PC, Mac, tablet, or mobile device, click here.
For more information visit The Boring Company website.
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