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by newyankee
2081 days ago
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I understand how reducing tunnel diameter by half reduces cost by a factor of 4. I can even imagine that using electric motors, batteries and few other optimizations might give an energy efficiency of 2-3x compared to current TBMs. However i find it difficult to believe that tunneling costs will reach 1 million $/mile. The different types of strata, energy costs, use of advanced tech like lasers/supercapacitors in parts might help. |
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Ans: From the most recent full presentation (pretty dated at this point Dec 2018): https://www.youtube.com/watch?v=nSIzsMlwMUY
From 10:22mins in the video: * Increase speed: automated segment erection and logistics; simultaneous mining and installation of reinforcement segments; 3X increase in power for TBM; continuous dirt removal; modified cutter design. Probably leads to 10X faster.
* 13:12mins: Decrease costs: onsite integration, reduced diameter of tunnels, electric locomotive, sell bricks. 15% of costs is dirt removal. Selling bricks for $0.10ea pays for dirt removal. 15% savings right there. (Price comparison: bricks cost $0.25 retail at Home Depot)
So the test tunnel cost $10mil/mi but can only put through 1/4 the area. So to balance against existing tunnels at $1bil/mi lets round up to say equivalent throughput for mass is $50mi/mile - assumes people throughput happens at the same speed of current mass transit - 45mph. Hyperloop tunnels will go much faster than that. But even non-hyperloop electric cars can go 90mph with self-driving - so double speed = double mass transfer and half mass_transfer cost per mile per time unit.
So kinda apples to kinda apples comparison of the very first tunnel Boring Co made is $50mil/mi versus $1bil/mil in LA for same mass throughput at same speed. They are already 1/20th the cost. Even if I am way off, by a factor of 10, the Boring Co is already HALF the cost of existing tunnels with their very first attempt in Dec 2018. The next update will put them even further along.