As opposed to garbage, maybe it should be human excrement. Such a nasty word. Lets use 'poop' instead.
Poop can take the form of whatever you place it around. It eventually hardens,and becomes fairly rigid. Not only that, you would get a fantastic base for future plant growth... once it decomposes a little. And, everyone living within the community could contribute. Instead of poop going down the toilet, like it does now, a pump would just shoot it out into the air, and it would disperse on top of all the other poop helping to form the tunnels. Plus, there's the added benefit that it is warm, so it would actually provide heat, after it comes out, so maybe it should sit around in a heat exchanger for some time before being blasted upwards. And if it's combined with urine (pee-pee), it's even more useful. then it can fill those cracks better, because it becomes more liquid. And we drink lots of water, so there is lots of pee-pee generated. Pee has the added benefit that we could water our crops with it. Plants like pee-pee.

That's fantastic. Today, people complain about living on what used to be old landfill sites, and having weird things leak into their basement, and gases bubble up from their lawn.

Imagine actually living within that toxic mass. Black goop dripping from the roof, noxious smells wafting through 1 foot concrete walls, seagulls everywhere. Isn't this really just a plan to speed up human evolution even faster? You want three eyed one horned burrowing purple people eating at McDonalds (because you would have to have an underground McDonalds).

I don't know if anyone else mentioned this, but ask Seattle how building on garbage as landfill worked. The fill will still be compacting for another 50 years or so, and it was done over a 100 years ago. Back then, they asked people to throw whatever they wanted into the fill in order to build up the land as you moved away from the Puget Sound, in order to lessen the steepness of the cliff that used to be there.

Hm. I don't have a good feeling when my kids play outside with their little shovels and I know that there's a landfill site underneath.

Here's another idea:
I don't like much driving through underground spaces. Just walls and adverts to look on, stale air and everything.
What about above ground Plexiglass tunnels? They wouldn't need to be fully enclosed either, just roofed over. Now it's bright, there are things to look at, fresh air and we don't need all that rubbish.

As for old and disabled people, there are Rickshaws.

"Almost everyone would ride a bike if they didn't need to worry about weather and traffic and hills"

Not if you're disabled, injured, sick, in pain (headache, bad back, etc), pregnant, fat, out of shape, have hemorrhoids, are an old person in typical condition, or are just plain tired.

Or if you were in charge of transporting one or more such people; how many of us could peddle any distance dragging the dead weight of another adult?

Or if you've got kids; even if their little legs could get them 10 !$%*! (or whatever), how would you keep them all with you rather than wandering around? And how about that 30 lb toddler that can't ride yet? How far could his exhausted mother peddle with him strapped in back? And what if she also has an infant? I know a lady with 5 kids under the age of 8; the mind boggles.

Or if you've got any significant weight or bulk to transport, and you're not Hercules that can pull a loaded wagon or trailer behind you. And no, it's not reasonable to expect that everything could be delivered, and even if you could do that delivery wouldn't be free, leaving the average family out of luck, not to mention that using engines to deliver everything everyone buys or needs to transport kind of negates the savings of not using cars.

Or if you'd like to get your frozen food home before it thaws, or your takeout home before it's stone cold.

Or if you'd like to arrive to your destination without stinking of sweat, and without having your clothes, hair and makeup (if you're a woman) wrecked with sweat.

Or if you're wearing a dress or skirt long enough to get caught in the works, or any clothing or shoes that you'd like to maintain in pristine condition.

Or if you just have a full enough life that you don't have remotely enough spare time to multiply your transportation time x 20 because you're biking instead of driving.

The wild garbage disposal days are over my friend. The advanced landfill techniques allow the garbage to be processed in anaerobic digesters and the resulting methane is used for electricity production. So when we have a solution for the garbage we have it doesn't make sense to build a tunnel and put garbage on it. I don't even start talking about methane production and possible explosions of garbage.

Future enterpreneurs ought to be reading this.

Garbage is not a good landfill, though. Too bad.

On the other hand, those bank tubes are a great prototype for your delivery scheme. In fact you could use the systems off the shelf, run them to each home, for small items like burgers, ordering computer memory, an iPhone, etc. Anarchists would put bombs in them however. Those bastards..

Not at all. I used to work in land development, and when they'd build up one side of a site with 8 - 12 or more feet of fill soil, I'd regret that they didn't place geothermal heat exchange pipes there first. (which are plastic, believe it or not. Low heat flow but so cheap they put more of it -it's optimum) You know, however, that experts are NOT in charge.

Oh, one more thing--to solve the problem of stability (assuming solid ground or incinerator ash is used for the tunnel base rather than loose garbage), don't build anything directly above the tunnels except sidewalks, with added reinforcement for crosswalks where vehicles would be driving over the tunnels.

Scott said,

"I was referring to crime in tunnels versus roads. But now that you mention it, has anyone died in a tunnel built in the past 100 years in the United States because of flood or earthquake? -- Scott"

I was going to respond that he conveniently forgot to mention fires. Lots of people have died in tunnel fires. Then I remembered that these would be for bicycles, which rarely burst into flames when they crash.

The biggest problem I can see is the sanitation (this is with the tunnels themselves, regardless of whether they're buried in garbage or nice clean dirt.) As someone mentioned, most tunnels in urban areas which have pedestrian access have a strong odor of urine. Ventilation can only go so far to reduce this. The tunnel system would need some way to be cleaned, preferably some sort of self-cleaning system. This would, of course, require a drainage system, which would also help somewhat in reducing the risk of flooding.

The idea of building the tunnels first and then burying them is brilliant, though.

I wonder if the people who take such glee in pointing how or why things won't work realize that they have a negative mindset.
They probably don't call it that though-- they probably have some exalted name for it, like "Supremely Practical". But really, they are just in the habit of saying 'No' to a new idea, and *then* explaining why they said no to it. Oh well, it's just a habit.
Oh and I agree that garbage will prove to be a valuable resource someday, therefore it may be too costly to use as landfill. But I like the bike tunnels idea, especially in certain areas. Vancouver, BC would be great-- way less crime than Washington DC and the citizens are motivated by the weather. There are a lot of bike commuters there already. You could light them with those solar pipes.

Scott,

You have to think like an engineer. Landfill cells are not geologically stable and landfill liners are imperfect. In other words, if your goal is a tunnel and basement with huge cracks which leachate will infiltrate through due to uneven settlement, this is an excellent plan. Stick to economics, monkey brain.

I like Roy_001's idea better. Incinerator ash is pozzolanic: Just add water and it basically turns into cement. With proper layering, the base would be stiff enough to support structures but probably soft enough to make creating tunnels, even after the fact, fairly easy.

That seems like the least stable foundation possible. You're talking about building large buildings on top of loose garbage on top of empty tunnels. Usually we put the base of large buildings in thick, heavy soil or rock. I wouldn't want to live some place where a small earthquake could sink the entire city.

Yea, not a good idea. Put the roads/transportation system underground. I read a book (can't remember the name now) where the transportation system was catenary shaped, evacuated (no air), nearly frictionless, tunnels. Basically the vehicles fell to their destinations via a kind of pendulum action with small energy inputs to overcame whatever friction still existed. 'All' we need is some cheap tunneling technology and there you go. Save the topside for the cyclist and pedestrians. Motor assited bikes with energy storage in the frame should take care of topographical changes in altitude.
I'll get right on it.

funny... WIRED has an article about small tunnels that delivers stuff to your house... http://www.wired.com/autopia/2009/08/someday-a-tiny-subway-will-deliver-your-groceries/

zeitgeist or just another proof that we're actually all computer programs?

Hi Scott, It's not the worst idea ever, but I think you greatly overestimate the amount of trash available. Also, trash will be recycled at some point, in some manner (not necessarily any sort of commercial recycling).

Not the worst, perhaps. Garbage will become valuable pretty soon. The amount of hydrocarbons and steel, aluminum should soon lead to re-excavation and recycling. I mean on a historical time frame, of course.
Better to just use robot tunnelers, if that's what you want to do. Excavation and tunneling is very dangerous work, so cost would come down with robots.

Aj city built on garbage? Well, I live in NY, so at least I know it's possible in theory.

Worst idea ever? No, actually, I think it's kind of cool, but others who are better at expressing themselves than I am have come up with some important flaws that would need to be addressed. (And after all what new idea DOESN'T have flaws to be worked out?)

These thought exercises are fun, maybe tunnel-dwelling can be incorporated into Cheaptopia.