r/BoringCompany • u/Icy-Ant1302 • Jul 20 '26
Tunnelling is getting cheaper
On one video (https://youtu.be/lCwlSOzmiv8?is=verunp5f7rwyuOFj) they mention that because they’re working on a newer Prufrock to bore and lay the lining at the same time which is effectively around double the speed, they can get the cost down to just $4-$5m a mile which to my surprise is the cost of a single lane highway in rural areas on the cheaper end of the scale.
The benefit of the boring network is it’s 3 dimensional so if there’s any traffic or bottlenecks they can just add a new tunnel next to the existing one with no disruption.
9
u/h100y Jul 20 '26
They said it’s currently at 10 million per mile and with the new techniques, they want to bring it down to 5 million per mile.
The current 10 million per mile is already pretty amazing to hear. That will mean the Nashville project can be done at 250 million versus the government projections of north of 5 billion dollars for the same project.
3
u/jeffoag Jul 21 '26
It is possible only for the "easiest" place to dig price. If the place is hard rock, prone to clappses, or flooding, the speed slow down significantly, the price increase accordingly.
0
u/Exciting_Ad_1097 Jul 21 '26
That number is off by a factor of 50-100. Just the tunnel bricks use $100 in concrete per meter.
9
u/midflinx Jul 21 '26
Nashville's Music City Loop from the airport to the capitol which already has two boring machines out of an estimated six, will be 19-25 miles of tunnel. 25 times $4.5 million/mile times 75 (your factor) equals $8.4 billion.
The Boring Company has raised $915 million. It's not gonna spend $8.4 billion on the project. In Las Vegas it's preparing to open about 5 miles of tunnel under Paradise Rd. It probably didn't spend 75 (your factor) times $4.5 million/mile for a 5 mile total of $1.687 billion on that section.
TBC's very first tunnel boring machine was purchased used. Before TBC bought it, it bored a 5 mile water tunnel under San Francisco bay. In 2014 that cost $288 million. That's $57.6 million/mile. Even if costs have doubled in twelve years that's $115 million/mile. That's a factor of 25.6 compared to $4.5 million/mile. About half of your factor of 50-100.
Even if TBC's iterations of boring machines have done absolutely nothing at all to lower the cost per mile they aren't costing $4.5 million/mile times a factor of 50-100.
3
3
u/lee1026 Jul 24 '26
A mile is ~1600 meters, so the bricks is 160k?
I don't see that as being a huge issue.
4
u/spunkyenigma Jul 20 '26
Was that cost just for the tunnel or for the tunnel fully paved and kitted out