The Boring Company Tunnel Event - December 18, 2018

[mongo]

Yes, there are options, most overly complex ones or risky ones that's going to take years of building and testing new technology (and the associated costs)... which brings me back to my main point. What do we need all this complex and expensive technology for when we solved this problem 115 years ago with subway cars on railroad tracks?

As I've said before, let Elon dig really cheap, really big tunnels. Then just run subway trains in them. Or if he wants to be a little fancy, mag-lev trains (not Hyperloop). That will actually solve the 'soul crushing traffic' problems that plague him and L.A. There's absolutely no way that any Loop system will come close to the passengers per hour that subways have been moving for over a century. Never.

We are not talking complex and expensive technology. It is not anything beyond what new cars can do. Our SUV has lane assist and adaptive cruise control. It is 99% percent of the way to working in loop (well, if it were an EV).

Instead of comparing Loop to subway in term of density and poo pooing it, why not compare it to roads and consider how it is better? No intersections, no weather, no pedestrians or animals, no surface construction disruption, no (human) driver error, minimal accidents.

One Loop tunnel cannot carry the equivalent passenger quantity of a subway when used by single driver vehicles. However, no subway can transport a person in a car anywhere, whereas Loop can expand to a number of tunnels equivalent to the traveler rate of any subway. Further, when used with full 16 person pods and platooning, an express Loop tunnel could carry more people than a subway track.

Reread the link you posted, subway expansion does not work for LA.

 

[HankLloydRight]

If true, then Loop isn't going to solve it either.

Loop can expand to a number of tunnels equivalent to the traveler rate of any subway.

Elon is never going to be able to get to the tunnel density required to solve the surface traffic problem.

 

[mongo]

If true, then Loop isn't going to solve it either.



Elon is never going to be able to get to the tunnel density required to solve the surface traffic problem.

In what sense? Traffic will expand if commuting gets easier, so capacity will get filled. On a purely theoretically point of view, you could make more tunnels than commuters, but it would be impractical.

From an engineering POV, the optimal solution is to put high rise housing in the downtown and eliminate commuting altogether, but that is not an option. Given that people do and will continue to drive to work, or commute through metro regions, how can new capacity for that commuting be created?

Many things in life do not totally solve an issue, but do improve it. If Loop causes people to switch to EVs for their commute, that is an improvement. If Loop's station density/ location causes people to use it instead of EVs, that is an improvement. For those that take loop, it could eliminate most of their soul destroying traffic, that's an improvement. Any traffic Loop handles reduces surface traffic which is an improvement.

 

[HankLloydRight]

Any traffic Loop handles reduces surface traffic which is an improvement.

Ok, but at what cost per person or per car per trip? Who's going to fund this boondoggle endeavor?

 

[ItsNotAboutTheMoney]

Ok, but at what cost per person or per car per trip? Who's going to fund this boondoggle endeavor?

The kind of people who're willing to pay $10 tolls and high parking fees every day, or who're willing spend thousands of dollars to get an HOV lane sticker?

 

[mongo]

Ok, but at what cost per person or per car per trip? Who's going to fund this boondoggle endeavor?

Why the disparagement? This is not a Springfield mono-rail.


Option 1: The same groups that funds the current infrastructure
If the tunneling 15x speed increase attempt only drops tunneling to 1/3 the cost (3 million a mile), Boring is on par with urban road construction, with higher capacity and lower maintenance costs Frequently Asked Questions - The American Road & Transportation Builders Association (ARTBA):

• Construct a new 2-lane undivided road – about $2 million to $3 million per mile in rural areas, about $3 million to $5 million in urban areas.
• Construct a new 4-lane highway — $4 million to $6 million per mile in rural and suburban areas, $8 million to $10 million per mile in urban areas.

Option 2: Private pay to ride (Chicago)
I already made a post showing the affordability.

First tunnel was <$10 Million a mile. Say the all in cost stays the same(ignoring any monetary improvement in a (potential) 14x speed increase). 30 year service life. $33,333 a month
Assume a ridership cost of $1 per mile (LA taxis is $2.85 just to get in, NYC subway is $2.75, NYC express bus is $6.50). Need 27,778 riders a month per mile, that is 926 people a day, or 39 people per hour per mile average rate.
Say 10,000 people use it a day and commute 5 miles each way on average. At $0.50 a mile ($1 round trip), 20*10,000*$1 = $200,000 a month, and say the cost per mile gets down to 3 million, those fares cover 24 miles of tunnel construction (4k people per mile average daily usages).

It is cost effective.

 

[HankLloydRight]

Yes, that works if you're just building one two mile tunnel on private property.

But once Elon starts going "3D" and having massively parallel tunnels, and longer than 5 miles, the engineering, surveying, and boring costs are going to increase phenomenally. There are also lots of unknowns when drilling that many tunnels parallel to each other -- like what underground structures or water tables or soft soil they might run into, or power, telecom, sewage, and waterworks they will have to reroute. All these are unknown and unpredictable expenses, especially boring 10x10 tunnels in "3D". And the deeper you go, the more expensive it gets, and as I already pointed out, getting cars to/from the surface to tunnels 10 deep is a significant challenge any way it's done through ramps, elevators, tunnel intersections or exchanges. Sure, it looks good on paper and cute little videos, but in reality, it's just not going to be that simple or that cheap.

 

[mongo]

Sure, it looks good on paper and cute little videos, but in reality, it's just not going to be that simple or that cheap.

Are there challenges? Sure. Are they show stoppers? No.

Yes, that works if you're just building one two mile tunnel on private property.

Entrance and exit were private property, tunnel is under city road. Future tunnels would be under right of ways/ easements also.

But once Elon starts going "3D" and having massively parallel tunnels, and longer than 5 miles, the engineering, surveying, and boring costs are going to increase phenomenally.

Why phenomenally, and not linearly? X CFM per minute of airflow needed. Surveying cost dependent on depth. One survey point covers all tunnel at that point to the surveyed depth, so it could cost less per tunnel.

There are also lots of unknowns when drilling that many tunnels parallel to each other -- like what underground structures or water tables or soft soil they might run into, or power, telecom, sewage, and waterworks they will have to reroute. All these are unknown and unpredictable expenses, especially boring 10x10 tunnels in "3D".

Geology is the reason for the survey. Tunnels will be placed to avoid existing utilities. These two items will reduce available locations for Boring, but does not negate the entire system. Finite element analysis can easily model what happens in the dense tunnel case. Consider that there are zero surface impacts to a tunnel dug two diameters below, why would additional tunnels be any different?

And the deeper you go, the more expensive it gets, and as I already pointed out, getting cars to/from the surface to tunnels 10 deep is a significant challenge any way it's done through ramps, elevators, tunnel intersections or exchanges.

Direct to lowest tunnel elevators, ramps, and spirals would cost more based on distance, and (for elevators) reduce vehicle transfer rate. However a dual path spiral allows continuous traffic into and out of any level at any location that support the needed diameter. Tunneling cost would not be any more based on depth. Place TBM, dig at a shallow downward slope, dig horizontally, dig upward, rise, repeat. Further, the lowest tunnels do not need to have direct surface accesses for vehicles (only for emergency escape and ventilation) they can be connected to/from the shallower tunnels and serve as longer distance express lanes. Just like you can't get to freeway express of HOV lanes directly from a surface street on ramp.

 

[HankLloydRight]

Tunneling cost would not be any more based on depth.

Sure it does. In order to start and stop drilling, you have to dig a really big hole in the ground to start tunneling or you have to start miles away at the surface to gradually bore down to the depth of the deepest tunnel. And then you have to move all the debris back to the surface, which takes time, energy and money the deeper you go. There's this thing called gravity.

You 'hand-wave' these problems away.. they just don't go away that easily.

 

[HankLloydRight]

they can be connected to/from the shallower tunnels and serve as longer distance express lanes.

Again, you just hand-wave this away as 'not-a-problem', but building these vertical interchanges and merges as tunnels is phenomenally more complex than just boring straight tunnels.

 

[1208]

For those that missed the video of the journey in the tunnel it's here...

 

[mongo]

Sure it does. In order to start and stop drilling, you have to dig a really big hole in the ground to start tunneling or you have to start miles away at the surface to gradually bore down to the depth of the deepest tunnel. And then you have to move all the debris back to the surface, which takes time, energy and money the deeper you go. There's this thing called gravity.


You 'hand-wave' these problems away.. they just don't go away that easily.

No hand waving, just not writing an entire procedure out. That entire tunnel is a usable tunnel. The initial sloping part is not waste. Yes, you will need to lift the diggings out, that extra effort is linear with depth. Around 11,000 pounds per foot of tunnel, ignoring the mass of the wall section descending. Energy need to move to surface is 4.15 Wh per foot of depth per foot of tunnel. One mile of tunnel 100 feet down requires about 2.2 MWh of energy to extract (ignoring digging), at 0.5 miles a day, that is around 400kW continuous or 530 hp. Not a show stopper.

Again, you just hand-wave this away as 'not-a-problem', but building these vertical interchanges and merges as tunnels is phenomenally more complex than just boring straight tunnels.

Again, no hand waving intended. I didn't realize you wanted more details on these things.

They need not be vertical interchanges (though that is space efficient and allows directional change, it is also slow). Spirals might work best for multilevel junctions.

To make a level tunnel junction, you can either dig a hole down to the joining point or fill a tunnel section with a low strength concrete mix, then drive a TBM on an angle through the previously dug tunnel. After creating the in and out cuts, reopen the original tunnel. This is easier with hard rock tunneling, but achievable in soft also.

Might make sense to dig all the straights first, then use specialized TBMs for the cross connections along with custom reinforcing segments.

A star/ hub topology would be the simplest with fast links between the different distribution points, requires more surface area though...

 

[HankLloydRight]

Ok, I'm done. It's never going to get to that level of complexity anyway. Never (not while I'm alive, anyway).

Elon might get one or two Point A to Point B tunnels built (like Chicago), but the fantasy of dozens of "3D" tunnels with spirals, elevators, exchanges and merges is just never going to happen. Quote me back when it does, and then we can talk about it. Until then, I'll just sit back and watch it never happen.