You know, Herman, I was walking through the Old City yesterday, looking at all those layers of history literally piled on top of each other, and it made me think about how much we take for granted what is happening beneath our feet. We walk on these ancient stones, but in cities like London or New York, there is this whole other mechanical world breathing underneath the pavement.
It is the ultimate hidden machine, Corn. And it is a machine that never sleeps, even when it is breaking down. Herman Poppleberry here, by the way, for those of you who might be joining us for the first time on My Weird Prompts.
Right, and we have a really interesting jumping-off point today. Our housemate Daniel sent us a prompt after listening to our last episode, episode eight hundred ninety-two, where we talked about the brutal reality of modern coal mining. He was thinking about the parallels between those dark, deep mines and our urban transit systems. Specifically, he is curious about the economics. Is it even feasible to build these massive underground networks anymore, or have the safety requirements and the sheer cost of retrofitting old tech made them a relic of the past?
It is a brilliant question because it touches on something called state capacity. Why could we build hundreds of miles of track in nineteen hundred, but we struggle to build two miles today? Daniel mentioned the London Underground and the New York City subway, which are the grandfathers of this tech. But he also brought up newer projects like the one in Thessaloniki, Greece, which finally opened after decades of delays.
It really feels like we are at a crossroads. We want the density and the speed of underground rail, but the price tag is becoming something that even the wealthiest nations on earth are starting to choke on. So, Herman, let us start with the basics. Why was it so much easier, or at least seemingly more viable, back in the late nineteenth and early twentieth centuries?
Well, the short and somewhat grim answer is that we cared a lot less about people back then. When the first sections of the London Underground—the Metropolitan Railway—were being built in the eighteen sixties, they used a method called cut and cover. They literally just dug up the street, laid the tracks in a trench, and roofed it over. It was incredibly disruptive, it destroyed entire neighborhoods, and the safety standards for the workers were... let us just say they were non-existent compared to today.
Right, no OSHA back then. No environmental impact reports.
Exactly. And the trains themselves were steam-powered at first! Can you imagine the air quality in those tunnels? They had to have these huge vents to let the sulfurous smoke out. But because there was no existing infrastructure to worry about—no fiber optic cables, no complex sewage systems, no high-voltage power lines—they could just rip through the earth. Today, when you dig under a city like New York or London, you are basically performing open-heart surgery on a patient who is currently running a marathon. You cannot just stop the city.
That is a great analogy. The "patient" is the city, and every time you want to add a new line, you are trying to navigate a maze of existing pipes and foundations. But Daniel’s point about the economics is what really strikes me. If you look at the Second Avenue Subway in New York, the first phase, which was only about two miles long and added three new stations, cost roughly four point five billion dollars. That is over two billion dollars per mile. How does that happen?
It is a combination of factors that people in the industry call the "cost premium." Part of it is the sheer complexity of the modern safety hardware Daniel mentioned. We are not just talking about tracks and a tunnel anymore. We are talking about massive ventilation systems that can clear smoke in seconds in case of a fire. We are talking about full accessibility—elevators and escalators at every single entrance to meet disability acts. We are talking about fire-suppression systems, communication networks that work deep underground, and positive train control systems that prevent collisions automatically.
And those things are not optional. You cannot build a "budget" subway today because the liability would be astronomical. If anything went wrong, the legal and human costs would dwarf whatever you saved on construction. But I wonder, is it just the hardware? Or is it the way we manage these projects?
Oh, it is definitely both. There was a fascinating study by the Transit Costs Project at New York University. They looked at why some countries build much cheaper than others. For example, Italy and Spain actually build subways for a fraction of the cost of the United States or the United Kingdom. In Madrid, they built the Metro Sur, which is a twenty-five mile circular line with twenty-eight stations, for about fifty-eight million dollars per mile. Compare that to the two billion per mile in New York.
Wait, fifty-eight million versus two billion? That is an insane disparity. What is Spain doing differently? Are they just ignoring safety?
Not at all. Their safety standards are just as high. The difference is often in the "soft costs." In the United States and the United Kingdom, we spend an enormous amount of money on consultants, legal battles, and what they call "bespoke" designs. Every station has to be a unique architectural marvel. In Madrid, they used standardized station designs. They bought their own tunnel boring machines instead of leasing them. They had a dedicated, experienced team within the government rather than outsourcing everything to five different private firms that all want a profit margin.
So it is a management and procurement issue as much as a technical one. But let us look at the "tipping point" Daniel asked about. If the cost is this high, are we going to see a shift toward above-ground infrastructure? I am thinking about things like light rail or even what they call Bus Rapid Transit, where you give buses their own dedicated lanes and stations.
We are already seeing it. If you look at mid-sized cities that are growing rapidly, they are almost never looking at heavy rail subways. They are looking at BRT because you can build fifty miles of BRT for the price of one mile of subway. But there is a catch. Density. If you are in a city like Hong Kong, Tokyo, or Manhattan, you simply do not have the surface space. You cannot move ninety thousand people per hour on a bus lane. You need the verticality of the underground.
That is the paradox, right? The cities that need subways the most are the ones where it is most expensive and difficult to build them. And then you have the maintenance of the old systems. Daniel mentioned retrofitting. Think about the London Underground. Some of those tunnels are over a hundred and fifty years old. They were built for small, four-car steam trains, and now we are trying to cram high-frequency electric trains with air conditioning into them.
And air conditioning is a huge problem! People do not realize that the clay around the London Underground has been absorbing heat from the trains for a century. It is actually getting harder to cool the tunnels because the ground itself is saturated with heat. To fix that, you need massive new ventilation shafts, but where do you put them? You have to buy some of the most expensive real estate in the world just to dig a hole for a fan.
It makes me think about episode seven hundred fourteen, when we talked about the challenges of keeping technology waterproof and resilient in harsh environments. A subway is basically a giant, inhabited humid pipe. The salt from the streets in winter leaks down, corroding the steel. The water table is constantly pushing against the walls. It is a miracle they work at all.
It really is. And to Daniel’s point about the economics, we have to look at the "second-order effects." Even if a subway line costs five billion dollars to build and loses money on every ticket sold, the economic value it creates by allowing millions of people to get to work without sitting in traffic is worth tens of billions to the city’s Gross Domestic Product. But the problem is that the "cost" is concentrated in a single government budget, while the "benefit" is spread out across the entire economy. It is a hard sell for a politician who has to justify a twenty-year construction project that will not be finished until they are out of office.
That is the "political horizon" problem. But what about the technology of digging itself? We have seen companies like The Boring Company, started by Elon Musk, claiming they can reduce the cost of tunneling by a factor of ten. They want to use smaller tunnels and more automated machines. Is that a real solution, or is it just high-tech hype?
Well, the jury is still out. The main issue with the Boring Company’s approach so far is throughput. They are mostly moving individual cars or small pods. That is not a subway. A subway's power comes from mass. If you are only moving two thousand people an hour, you haven't solved the transit problem for a major city. However, their focus on making tunnel boring machines faster and more continuous—meaning they dig and install the tunnel segments at the same time—is a legitimate engineering goal. If we could make digging sixty percent cheaper, the economics of the underground would change overnight.
I also wonder about the "safety hardware" Daniel mentioned. Is there a point where we have over-engineered these systems? I am playing devil’s advocate here, but are we demanding a level of perfection that makes the "good" impossible?
It is a sensitive topic. No one wants to be the person who says "we should have fewer fire exits." But there is a legitimate argument that some of our modern codes are based on worst-case scenarios that are extremely unlikely, or that they do not take into account how modern materials are less flammable than they were fifty years ago. For example, in the United States, the distance required between emergency exits in a tunnel is much shorter than in many European countries. That means you have to dig more vertical shafts to the surface, which is one of the most expensive parts of the project. If you could double the distance between those shafts without significantly increasing the risk to passengers, you could save hundreds of millions of dollars.
It feels like a legacy of fear. We have these disasters in our history—like the King's Cross fire in London in nineteen eighty-seven—that fundamentally change the regulations. And those regulations never go away; they only accumulate. It is like the geological layers of the Old City we were talking about. Each new safety rule is a new layer that the next project has to dig through.
Exactly. And let us not forget the archaeological layer! Daniel mentioned the Thessaloniki Metro. One of the main reasons that project took decades was because every time they moved a shovelful of dirt, they found a Byzantine church or a Roman road. You cannot just steamroll over history in a city like that. You have to stop, bring in the archaeologists, and document everything. That is a massive cost that above-ground infrastructure mostly avoids.
So, looking at the "tipping point" idea... are we seeing a world where only the super-wealthy cities or the highly authoritarian ones can build subways? I mean, look at China. They have built thousands of miles of subway in the last twenty years. Is that just because they have cheaper labor and fewer legal hurdles?
Labor is part of it, but it is also "state capacity" and "scale." Because they are building so much, they have an entire industry that is incredibly efficient at it. They have standardized everything. They have a massive fleet of tunnel boring machines and a workforce that knows exactly what to do. In the West, we often treat every new subway line like a unique, artisanal project that we have forgotten how to do since the last time we tried it twenty years ago.
It is like we are relearning how to build a pyramid every generation. It is incredibly inefficient. But I want to pivot back to the "above-ground" alternative. If you are a city planner in twenty-twenty-six, and you are looking at the costs we are discussing, how do you justify going underground? Is there any scenario where it is not just a "luxury" for the elite?
It is justified when you look at the cost of the alternative. If you do not build the subway, what happens? You build more roads. You deal with more pollution, more accidents, and more lost time. If you value a human hour at, say, thirty dollars, and your subway saves a million people thirty minutes a day, that is fifteen million dollars a day in economic value. Over thirty years, that pays for a lot of tunnels. The problem is that we are very good at measuring the cost of a project and very bad at measuring the cost of doing nothing.
That is a profound point. The "cost of inaction" is invisible on a balance sheet. But let us talk about the human experience of these retrofitted systems. Daniel mentioned the "haunted" aspect of the London Underground. Beyond the paranormal, there is a psychological weight to being in a space that is clearly a patchwork of nineteen-hundreds brickwork and twenty-twenties digital screens.
It is a "palimpsest," Corn. A surface that has been written on, erased, and rewritten. You see these old tiles from the nineteen-twenties next to a high-definition advertising screen. It creates this sense of "technological vertigo." And for the workers, it is even more intense. Imagine being a technician trying to fix a modern fiber-optic signaling system that is laid over a copper wire network from the nineteen-fifties, all inside a tunnel that was hand-dug in eighteen-eighty.
That sounds like a nightmare. It is like trying to install a modern operating system on a computer made of clockwork. And yet, we have to do it because we cannot afford to let these systems fail. If the New York City subway stopped for a week, the city’s economy would literally collapse. It is a "too big to fail" piece of infrastructure.
Which brings us to the "tipping point" Daniel asked about. I think the tipping point is not that we will stop building underground, but that we will change how we build. We are seeing a move toward "automated" metros—trains without drivers—which allows for much higher frequency and smaller stations. If the trains can run every ninety seconds with perfect precision, the platforms do not need to be as long. Smaller platforms mean smaller stations, which means lower costs.
So the solution to the high cost of modern safety and hardware is... more technology? It is like we are doubling down on the complexity to solve the problems created by the complexity.
In a way, yes. But it is also about simplicity in design. The most successful modern systems, like the ones in Copenhagen or Singapore, are highly automated and very standardized. They do not try to make every station a cathedral. They treat it like a utility. I think that is the shift we need to see in the West. We need to stop treating transit as a "monumental" architectural project and start treating it as a "logistical" one.
I think that is a really key takeaway. If we want to keep our cities livable, we cannot give up on the underground. But we might have to give up on our "artisanal" approach to building it. We need to find that middle ground between the "no-safety" era of the eighteen-sixties and the "over-regulated" era of today.
And maybe we need to look at what Daniel’s prompt was really hinting at—the human cost. Whether it is a coal mine or a subway tunnel, being underground is inherently taxing on the human body and spirit. If we are going to ask people to spend an hour of their day in a tube under the earth, we owe it to them to make it safe, efficient, and, dare I say, a little bit pleasant.
Even if it is "haunted" by the ghosts of nineteenth-century steam engines.
Especially then! It adds character. But seriously, the economics of these systems are the economics of the future of the city. If we can't figure out how to move people efficiently beneath the surface, our surface cities are going to become increasingly clogged and unworkable.
It is a fascinating challenge. I am really glad Daniel sent this in. It is one of those things you use every day—or at least you see in the news every day—but you rarely stop to think about the incredible layers of math, law, and engineering that are keeping those tunnels from collapsing.
And the incredible amount of money. Never forget the money. It is the fuel that moves the dirt.
Well, on that note, I think we have dug deep enough into this one for today. If you are listening to this and you have your own "weird prompt" about infrastructure, or history, or anything else that keeps you up at night, we would love to hear from you. You can find us at myweirdprompts.com. There is a contact form right there on the site.
And if you have been enjoying our deep dives—whether it is coal mines, missile defense systems like we discussed in episode eight hundred eighty-nine, or today's look at the underground—we would really appreciate it if you could leave us a review on your podcast app or on Spotify. It genuinely helps other curious people find the show.
Yeah, it makes a huge difference. We are available on Spotify and pretty much everywhere else you get your podcasts. Just search for My Weird Prompts.
Thanks to Daniel for the prompt, and thanks to all of you for listening. It is a wild world out there, both above and below the ground.
Stay curious, everyone. This has been My Weird Prompts. We will see you next week.
Until then, watch your step on the platform.
Nice one, Herman. Bye, everyone.
Goodbye!
You know, I was just thinking about that Thessaloniki project again. Did you see that they found a headless statue of Aphrodite while they were digging?
I did! Can you imagine being the project manager and having to call the mayor to say, "Hey, we found another goddess, add six months to the timeline"?
It is a tough job, but someone has to do it.
Better them than me. I prefer reading the papers about it from the comfort of our living room.
Exactly. Alright, let's go get some coffee. I think I've had enough of the "underground" for one morning.
Lead the way, Corn.
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See ya!
