Rumbling Underground, An Engineering Feat In 2009, 1.6 billion people hopped on the New York City subway. But how was it built? MTA Capital Construction president Michael Horodniceanu and historian Clifton Hood discuss the engineering techniques used to tunnel through Manhattan — from sticks of dynamite to a one-million-pound tunnel-boring machine.
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Rumbling Underground, An Engineering Feat

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Rumbling Underground, An Engineering Feat

Rumbling Underground, An Engineering Feat

Rumbling Underground, An Engineering Feat

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In 2009, 1.6 billion people hopped on the New York City subway. But how was it built? MTA Capital Construction president Michael Horodniceanu and historian Clifton Hood discuss the engineering techniques used to tunnel through Manhattan — from sticks of dynamite to a one-million-pound tunnel-boring machine.


You're listening to SCIENCE FRIDAY. I'm Ira Flatow.

Oh, way back when, I once asked the legendary New York newspaper man Jimmy Breslin what it was that made New York City the great city that it is. Was it the World Trade Center, the stock market, the garment industry? Believe it, at one time it employed 250,000 people in New York City.

No, he said. What made New York so great is its subway system, a system that allows New Yorkers to go - they can go to work in one place, live in another. They can get from A to B cheaply and easily. And if you've ever been to New York City, you know how true that is. Over five million riders pass through those turnstiles every weekday.

But even while riding in these underground tunnels, it's easy to take them for granted. It's easy to forget the engineering challenges behind the creation, all those tunnels that had to be carved out of the Manhattan schist, the bedrock of Manhattan Island; concrete that had to be poured for the platforms. They had to lay the track, each individual tile. There are some gorgeous tiles in the New York City subways. If you're in the subways, look at those tiles. They're magnificent. Each one of them, one by one, had to be cemented into place and all of this to create one of New York City's truly distinctive landmarks, the subway.

And it's been wowing people for a while now. Back in 1905, there was a tour guide in 1905, the Rand McNally tour guide, told people who wanted to visit New York: The tourist will be well-repaid by a trip through the burrow of this greatest of all underground railways.

How did they make it? How did they make the subway system? For the rest of the hour, we're going to be talking about the engineering behind this massive train network, how they tunneled through the island 100 years ago, sometimes - sometimes with fatal consequences, and how they are still drilling today.

They are excavating, as we speak, a few blocks from here a huge cavern right under Grand Central Station. How do they do that all without damaging the foundation of the busy city above? How do they do it without cutting electric cables, water mains, sewer pipes?

How do they keep - you know, the city is surrounded by water, rivers. It's an island. Manhattan is an island. How do they keep all that water out? Well, if you'd like to ask, our number is 1-800-989-8255. You can also tweet us, @scifri, and talk about the subway systems.

I'd like to introduce my guest. Clifton Hood is the author of "722 Miles: The Building of the Subways and How They Transformed New York," a professor of history at the Hobart and William Smith College in Geneva, New York. He joins us from Cornell University. Welcome to SCIENCE FRIDAY.

Professor CLIFTON HOOD (Hobart and William Smith Colleges): Thanks, Ira. I'm looking forward to this.

FLATOW: You're welcome. My next - also with me here in New York is Michael - I'm going to get your name wrong - Horodniceanu. Did I get that right?

Mr. MICHAEL HORODNICEANU (Capital Construction Company, Metropolitan Transportation Authority): Yes, you did.

FLATOW: Michael Horodniceanu is president of the Metropolitan Transportation Authority's Capital Construction Company here in New York, in our studios. Welcome to SCIENCE FRIDAY.

Mr. HORODNICEANU: Thank you.

FLATOW: Let me ask you first: What does the MTA Capital - what does MTA Capital Construction do? What's their job?

Mr. HORODNICEANU: The MTA Capital Construction Company was formed specifically to carry out the mega-projects in New York, and these are the projects that involve the construction of the expansion of the subway system in somewhere over 70 years.

We are basically charged to build the extension of number 7 to the West Side of Manhattan.

FLATOW: The 7 train.

Mr. HORODNICEANU: That's correct. The Second Avenue subway, that phase one, that will go from 96th to 63rd Street, the East Side Access, this is bringing the Long Island Railroad trains into Manhattan on the East Side under the Grand Central. We are about 140 feet below the surface there. As well as the Fulton Transit Center. That area is in Lower Manhattan, the intercept of 11 of the 22 subway lines, and in addition to that, we have the PATH there, so it's an incredible interchange.

FLATOW: Wow, a lot of work. Tell us the ABCs of building a subway tunnel. I mean, how does the actual blasting, grinding go - how does it go on?

Mr. HORODNICEANU: I was going to say, the first thing, we need money.

(Soundbite of laughter)

FLATOW: You are certainly a New Yorker. (Laughing)

I mean, let me ask Clifton Hood. In the old days, they just used - they blasted it out with dynamite?

Prof. HOOD: Well, I think Michael's answer that they need money is the best one. That's always been true.

The original subways were really built by hand. They used dynamite, but there were people using picks and shovels. They had almost no mechanized equipment like we would think of today, bulldozers. It was remarkably labor-intensive. And I think that's probably the biggest change to today.

FLATOW: Michael, you agree?

Mr. HORODNICEANU: Well, partially. The subways of the past were primarily what we will call today cut and cover. That means we cut a channel into the street, and then we end up building the walls, and it's irrelevant for the moment how we - what was done, it was done by hand, and the material used was concrete, was cast iron, whatever way it was done.

But it was done by cutting channels into the street. I have, in the lobby of my office, pictures of the building of the IRT along Broadway, in which there are two huge channels to the left and right, where the roadways are today, with total disregard of what happened to pedestrian traffic, to people living in adjacent buildings or anything.

That thing is a thing of the past. What we have today is - the biggest difference is that, number one, we have to build in a much denser urban setting, in which we upset many more people than before, people that now look at the environmental impacts that were - at the beginning of the 20th century were really - they existed, but people did not know what they were called, so therefore they didn't complain.

And today we have - the biggest difference is we have what is known as a tunnel boring machine. That means we can actually bore tunnels at a much greater depth than before in a mechanical fashion. That means we can advance much faster than we would have done it in the past, when we actually needed to shoot and blast. That means we put dynamite, blasted it, hauled it out and then repeated that over and over again.

FLATOW: So this machine is like - I've seen pictures of it. It's like a giant disk that rotates and cuts through the rock.

Mr. HORODNICEANU: Right. The front of the machine is a 200-ton disk that cuts through the rock. Now, there are various types of machines, but to make it simple, the one that is being used primarily now, in rock, has lateral grips. Think of it as some shoes that press against - like a brake that presses against the sides of the tunnel. That keeps the machine in place. And beyond that, the machine, by rotating, cutting and crumbling the rock, is advancing.

Now, only the head of the machine advances, up to about six feet, and then the rest of the machine, the gear that is up to 850 feet long, will follow through.

So think of it as an inchworm. And the cabin that actually the machine is controlled from, or the electronics in which we really keep the alignment - remember, we have to go in a certain direction, a certain slope, left, right, whatever that it is.

Think of it as the Jules Verne books, in which...

FLATOW: I've seen that picture...


FLATOW: A giant screw, pulling the stuff out...

Mr. HORODNICEANU: Right. So that's what we are doing, in effect.

FLATOW: Clifton Hood, now, when they first started building the subways, did they know what was down there that they were digging into?

Prof. HOOD: No, they actually didn't. Skyscrapers were just getting underway. William Barclay Parsons, who was the chief engineer of the first IRT tunnel, put a lot of test bores down underground and was really surprised to discover that the level of bedrock varied so much over the course of Manhattan.

It's very close to the surface around Wall Street. It dips in Greenwich Village and Chelsea, and then it comes up closer to the surface around what we now call Midtown. And this just wasn't known, and the engineers like Parsons had to come up with a way of dealing with it.

And this also directly affected where they put the tunnel. Were they were going to put it really deep underground? They decided not to do that because they were afraid that people wouldn't go down and use the subway, and they were worried about escalators, elevators, ventilation.

Were they going to put it at medium-depth? They decided not to do that because they would have had to cross what engineers call a mixed face. And so they decided to put it very close to the surface.

FLATOW: And that's why you see skyscrapers are not evenly spaced on Manhattan. They're where the bedrock is closer to the surface, like the...

Prof. HOOD: I think that's part of it.

FLATOW: Midtown and downtown.

Prof. HOOD: I think that's part of it. But another reason is that downtown just is where New York City started. And Midtown is where the two great railroad terminals are: Grand Central and Pennsylvania Railroad. And I think that precipitated changes in those areas too. So in a way, we really got lucky.

FLATOW: Let me ask you, Michael. With all these skyscrapers above, when you're digging these tunnels below, how do you keep them from not - you know, they're so plumb and whatever, and they're sitting on - from vibrating and just twisting about enough that they might collapse underneath?

Mr. HORODNICEANU: I have to tell you that, actually, the biggest challenge are not the skyscrapers but the utilities.

FLATOW: You mean the water and electricity...

Mr. HORODNICEANU: Yeah. And I want to read you - just actually, I...

FLATOW: You'll get back to answering that question, but...

Mr. HORODNICEANU: But I want to read you something so you'll understand. The - and this is actually taken out of a magazine. The present interruption to traffic, the interminable and absolutely stupid way in which our choicest streets are dug up, relayed and dug up again in a perpetual and obtrusive nuisance, which would not be tolerated in any provincial town and cannot be too soon removed from the streets of one of the greatest cities in the world - this is the story of our utilities, okay, that you see - all the cuts in the streets. By the way, this is an article in the Scientific American, May 25th, 1901.



FLATOW: You could have written that today, is what you're saying.

Mr. HORODNICEANU: Absolutely.


Mr. HORODNICEANU: So now I'm going to - this is important to understand what we're doing because a lot of the work that is so complex today, particularly in certain parts of the system - at least in our work that we have done that we have to have started up pits where we drop this tunnel-boring machine and so forth, that we do cut and cover. And we have to move all the utilities around, so that's an issue.

But to answer your question, the skyscrapers are really well-designed, okay, and many of them have a foundation on rock. And at the level and the location that we are actually boring, we are not disturbing them. Yet we have what I refer to as the fragile buildings, and along Second Avenue I have identified about 225 of them in the area that we're working. These were buildings that were put together in - built at the end of the 19th century, somewhere, 1860s to 1890s, on a rubble foundation. And every time we go by, they vibrate. They - we are very careful to...

FLATOW: I've been in a few of those.

Mr. HORODNICEANU: ...make sure - we're making very - we're very careful to make sure that nothing happens. Our biggest tunnel, the one that we're doing for the East Side Access, is 140 feet below ground. Quite frankly, no one knows we exist. It's a stealth project. We're going there and we continue to go, similar to the third water tunnel that was just like that.

FLATOW: We're talking about subway construction this hour on SCIENCE FRIDAY from NPR. I'm Ira Flatow.

Clifton Hood, how did they tunnel under rivers back in the old days? I mean, are there a lot of tunnels under the East River or subways, things like that?

Prof. HOOD: They started building tunnels under the East River and the Hudson River in the 1880s. But the technology wasn't really good enough. Both of what we call the Steinway Tunnel and what's now the PATH tunnel came to an end. They went bankrupt. They had problems with accidents.

But the real difference was made in the 1890s when a British engineer named Greathead devised a better shield, maybe the grandfather to the bore that Michael was talking about, although a lot different. But this provided covering for workers. This allowed them to bore ahead, and they were able to make progress. And both the Hudson and Manhattan, now the PATH train, and the Steinway Tunnel, were completed in the first decade of the 20th century.

FLATOW: Mm-hmm. So this was sort of a protection device for the workers.

Prof. HOOD: It was a protection device and partly a cutting device too.

FLATOW: Uh-huh.

Prof. HOOD: But it was still dangerous.

FLATOW: Did they have trouble convincing people to go in a subway that was going to go under the water? To ride in a train that...

Prof. HOOD: They did. They did.

FLATOW: You know, when I was a kid going through all the tunnels on the cars in New York, in the subway, I was always wondering where's that leak going to come from, right?

Prof. HOOD: Well, you refer to Manhattan as being an island. We don't think of it that way because of all the bridges and tunnels. But it was an island city, and a lot of people worried about going underground, especially when they heard about accidents in this construction. And they were worried that the tunnel - that the trains would get stopped. They'd be worried that the water would come in. And this happened sometimes during construction. So, yeah, people were worried.

FLATOW: Were they - were there fatalities in this - some of this must have been...

Prof. HOOD: In the construction?


Prof. HOOD: Yeah. Well, I think the interesting story there is that one of the real problems in building the subway tunnels was that the workers would get the bends. And they used to wear labels, badges on their jackets that would say: If found unconscious bring me to the hospital at Gate Q. But the really striking thing was that a disproportionate number of African-Americans were hired as the laborers to build these tunnels. Because a story got told that they were somehow immune to the bends. That's total nonsense. But that is what some people wanted to believe. And so you see racism making its way in the construction of the subway. And they weren't hired in disproportionate numbers in other parts of the subway construction.

FLATOW: Why would they get the bends? What - you know, that's like from pressurized air down there?

Prof. HOOD: Yeah.

FLATOW: To keep the water out?

Prof. HOOD: Yeah. Yeah.

FLATOW: Michael?

Prof. HOOD: The same...

Mr. HORODNICEANU: I'm sorry.

Prof. HOOD: No, that's okay.

Mr. HORODNICEANU: In general, if you really drilled through rock, you did not need a pressurized environment. But the moment you had either water penetration or you're on soft ground, you needed to work in a pressurized environment. The pressurized environment normally imply that you're going to be at somewhere around two to three bars. Just so you understand, one bar is the equivalent, if we want to look at - in a different way. If you go - if you are going to go down into the water, right, and you're going to scuba dive...

FLATOW: Right.

Mr. HORODNICEANU: ...30 feet is acceptable. That's about one bar.

FLATOW: One atmosphere.

Mr. HORODNICEANU: That's right. So you're not going to suffer if you come up - you know, it's fine.

FLATOW: Right.

Mr. HORODNICEANU: Once you go above that, the - you create - if you move fast up, the nitrogen in the blood tends to bubble and it goes into your joints and so forth. So you need a decompression time that potentially the people, when they did that - and Brooklyn Bridge is a good example of one, the foundation...

Prof. HOOD: Yeah.

Mr. HORODNICEANU: ...they did not know what created that. So that's...

FLATOW: They got the bends.

Mr. HORODNICEANU: That's correct.

FLATOW: We're going to take a break and come back and talk more with Michael Horodniceanu and Clifton Hood, author of " 722 Miles: The Building of the Subways and How They Transformed New York."

Our number is 1-800-989-8255. And you can tweet us @scifri, @-S-C-I-F-R-I. What is there you'd like to know about building subways that you don't already know or we haven't talked about? Stay with us. We'll be right back after this break.

(Soundbite of music)

FLATOW: I'm Ira Flatow. This is SCIENCE FRIDAY.

We're talking this hour about building a subway, digging all those tunnels out, especially here in New York, with my guest Michael Horodniceanu, who's president of Metropolitan Transportation Authority - we call it the MTA here - the Capital Construction Company here in New York. Clifton Hood, author of " 722 Miles: The Building of the Subways and How They Transformed New York."

Lots of phone calls today. Let's see how many we can get in. And let's go to the phones. Let's go to Paul in Smithtown, New York. Hi, Paul.

PAUL (Caller): Hey, great show. Love it.

FLATOW: Thank you.

PAUL: What happens - I understand how the machine basically bores and is guided. What do they do with the waste and how does that machine get rid of it?

FLATOW: All right. Michael, you want to tackle that?

Mr. HORODNICEANU: Yeah, absolutely. We have - in effect, we are carrying it from the machine, outside - and depending on the project, sometimes a few miles from the location - on a conveyor belt. And then it goes into one specific location. And from there it's hauled, it's trucked away.

This material, depending - and if you're talking about the tunnel-boring machine and rock, it is really dust that goes out, because it's being crumbled. The mica schist that we have - the Manhattan schist is really made out of mica and it looks dusty, and if we put water it actually gets muddy, and is being just carried away.

FLATOW: Mm-hmm.

Mr. HORODNICEANU: Sometimes it just goes to the end of the machine, 850 feet. And it gets loaded into...

FLATOW: But where do they dump it when they...

Mr. HORODNICEANU: Oh. It goes - I mean, some of it, for example...


Mr. HORODNICEANU: right now a part of the Brooklyn Bridge Park.

FLATOW: Landfill.

Mr. HORODNICEANU: Yeah. We put it there. You know, that's - and most of it is going away. And quite frankly, there are people that would like to know, including myself, exactly where they end up. I'm not sure.

(Soundbite of laughter)

FLATOW: Some future civilization. All right. Thanks for calling, Paul.

PAUL: Thank you for the answer. I was just trying to figure it out and I love machines.

FLATOW: We all do. Thanks for calling.

PAUL: Thank you.

FLATOW: In fact, when they built the World Trade Center and they had all that stuff to dig up, they...

Mr. HORODNICEANU: It's called today Battery Park.

FLATOW: Battery Park. Yeah. Did they have those problems back then, Clifton, what to do, in the old days?

Prof. HOOD: They did. They put a lot of landfill around Governor's Island, around Lower Manhattan, same thing.

FLATOW: Okay. Let's - a lot of people have interesting questions. Let's go to Allison in Orlando. Hi, Allison.

ALLISON (Caller): Hi. Good afternoon. I was wondering how you actually get the boring machine into place in such a densely populated area. It's not like the side of a mountain where it's open. How do you physically get it into place?

FLATOW: Into a tight little spot there.

Mr. HORODNICEANU: Right. Normally, like, as an example, we did for number 7 and Second Avenue, we created a launching pad underground. It's a real launching box that is about - on Second Avenue - 80 feet down, about 70 feet wide. And we have an opening on the roadway and we lowered it piece by piece, and then it is assembled down into the pit. And it's being activated. It's a very complex thing. And then we start moving into position to - into what we refer to it as a starter tunnel and we start boring.

As we're advancing, we're adding pieces to it. They move on a rail, by the way, that is being laid down. And as we advance, the rail is being actually added to it. And these machines normally end up very long, like 850 feet. At the end of the run, we disassemble it and we pull it back. And the head cover that is 200 tons is being taken apart into pieces and then hauled out and then just out...


Prof. HOOD: ...of the launching box. But at the same time, sometimes we take the road - the head of the machine and we leave it in place for the future generation to find it.

(Soundbite of laughter)

FLATOW: So that a thousand years from now, when they dig up the tunnels...

Mr. HORODNICEANU: Right, 200 years they will find something and say, what was that?

FLATOW: What the heck is...

Prof. HOOD: It might take that long to get money to extend the lines too.


FLATOW: And finish the Second Avenue, if it ever gets done. Clifton, how did they decide on electric trains? I mean, we're now in an era where electricity is magic, so to speak, that point 125, 30 years ago, right?

Prof. HOOD: No, that wasn't the case at all. In the 19th century there was a real search for a mode of power. The first subway in the world is in London in 1863. And they use, of all things, steam power. Trains there ran in open cuts, and yet they still vomited out this smoke and cinders and exhaust.

When the subway - when New York subway was being developed in the 1890s, electric power was just about five or six years old. And so the chief engineer goes over to London. He goes to the very first electric subway - electric-powered subway in the world, the city in South London. He looks - sees that it works. They come back, and they decided to go with it.

It's a bit of a gamble. Most mass transit innovations take place not in big cities like Tokyo or New York City but rather in smaller places. The first feasible electric railway is in Richmond, Virginia. And the reason for that is that if something goes wrong in New York City, it is a disaster. You've got tens of thousands of people who can't get to work.

FLATOW: Well, where was the...

Prof. HOOD: And so...

FLATOW: Yeah. That's interesting. Where is the invention of the subway sandwich? Why is that related to the New York City subways? It's called something - it's something else in every other city. Why...

Prof. HOOD: Yeah, it really is. I don't - I've always guessed it must be the shape. But I do know that it used to be, at least, that you would go into Subway shops and - well, I would be doing a research in Lower Manhattan, and I would come out for lunch, and I go to a Subway shop. And I would look at my research scattered across the walls, because they had this wallpaper that showed the original kiosks...

FLATOW: That was my next question. I think - is that the real stuff? Is that really the real - you're saying it is.

Prof. HOOD: Yeah, it is. It is. It is.


Prof. HOOD: There was a New York Times or there was a New York City paper from October 27, 1904, that's the day the very first subway opened. And that's what I'm saying. That's literally my research and making its way to wallpaper.

And I know the Subway restaurants start in Connecticut, but somebody must have - or it must have been one of your callers. They must be in love with it just like, I think, so many people are.

FLATOW: 1-800-989-8255. You answered the question, I have always wondered about the Subway sandwich shops. Laura in Victor, New York. Hi, Laura.

LAURA (Caller): Hi.

FLATOW: Hi, there.

LAURA: Good to speak with you. You got a great show.

FLATOW: Thank you.

LAURA: Even though I live in Victor, New York, which is near Rochester, I was born and raised in the Bronx. And some of my earliest memories are of the subway in the - from the '50s. I used to think that the subways were singing a song because of the rhythm of the subways. We traveled on the subway a lot as a very, very little girl. And I would get kind of irritated when no one else could hear the songs that the subways were singing.

But I also wanted to share an incredible novel about the building of the subways called "This Side of Brightness" by Colum McCann, and it follows a group of sandhogs and then subsequent generations. And it's about both the subways in a historical context, and also in a kind of psychological and mythical context. And it's absolutely beautiful. And for anyone who has a relationship with the subways, it's really an incredible experience to read that book. And so I thank you for your wonderful program.

FLATOW: Thank you for that recommendation and have a good weekend. Clifton, you ever heard of that book?

Prof. HOOD: Yeah. I think that the thing is that you really do need novels. They are very few records left of the workers who built the subways in the - well, from 1900 to about 1940. Their story's really been lost.

FLATOW: Hmm. Michael, let me ask you about a project that you're working on, where I've heard that you have to freeze the ground...


FLATOW: ...before you dig it.

Mr. HORODNICEANU: In a number of locations, we're doing it.

FLATOW: Tell us about why...

Mr. HORODNICEANU: Well, here is the thing. As you know, and I think that it's been mentioned before, that the geotechnical makeup of Manhattan is really kind of spotty, so to speak. We found out that Second Avenue, on the west side of Second Avenue, the rock is relatively okay. But it precipitously falls towards the East River. So there is a location. There is a spot, there is a stretch, in around 92nd and 91st Street where the ground, the rock is totally fragmented, we have lots of water. And there's a fear is that if we go there and we go with a TBM, we will not be able to go through without the potential collapse.

So what we have done is to introduce long pipes that go down about 90 feet or so. These are then filled up with brine. We have a couple of refrigeration units outside, and we're literally freezing the ground. It takes about 12 - 10 to 12 weeks to do that. Once it's done, we're going to go in with a TBM. We're going to cut...

FLATOW: Excuse me. TBM is a...

Mr. HORODNICEANU: TBM is a tunnel boring machine.

FLATOW: Right.

Mr. HORODNICEANU: We're going to cut through the pipes, by the way.

FLATOW: Leave them there.

Mr. HORODNICEANU: Oh, yeah. We're not - we're cutting through that, right?

FLATOW: Right.

Mr. HORODNICEANU: And then, obviously, we're going to immediately close the area to make sure that it's well supported. And then we're going to defrost the ground in a very careful, orchestrated way so we will not affect the buildings around it. That when you freeze ground, the freeze and thaw cycles tend to actually move the ground up and down, and this is something that you do not want to do to the buildings surrounding it.


We have done that on 11th Avenue, up with the Number Seven, on a stretch of about 400 feet. We're doing it on a major thing. We're doing a very short tunnel, 120 feet under the Northern Boulevard that carries two subway lines, one on top of other. And we have to do that while supporting the subway. So, again, we're now doing horizontal freeze.

FLATOW: Yeah. Wow. Let me - here's a question, a tweet that came in from St. Louis, who asks scifri - says, how do you tell where you are in a tunnel? I mean, because GPS won't work down there. You don't have the sun, the moon, whatever to take bearings. How do you know exactly where you are in the tunnel?

Mr. HORODNICEANU: Remember I told you about the cabin?

(Soundbite of laughter)

Mr. HORODNICEANU: Well, first of all, surveying...

FLATOW: And you'll have to meet another tunnel sometimes, right?

Mr. HORODNICEANU: Sometimes, yes. Surveying equipment has been around for many years and...

FLATOW: Right.

Mr. HORODNICEANU: ...we did not have GPS. When I went to school, I learned how to survey and put location without having to have GPS.

FLATOW: Right.

Mr. HORODNICEANU: Okay? People navigated boats and airplanes using the stars sometimes.

FLATOW: But - that's what they're saying, though. Underground, you don't have the stars.

Mr. HORODNICEANU: You don't have the stars, but it's a much smaller environment. You know exactly where you are in terms of - because you can survey it, so you would know vis-a-vis the point that you start behind you, okay?

FLATOW: Mm-hmm. Uh-huh.

Mr. HORODNICEANU: Where you're going to be in terms of elevation and in terms of lateral movement. So that's actually not such a complex thing...

FLATOW: There you go.

Mr. HORODNICEANU: ...and we're doing it. I really wanted to, because I know you...

FLATOW: Let me just remind everybody. This is SCIENCE FRIDAY from NPR.

Go ahead. I'm sorry.

Mr. HORODNICEANU: I really - remember, I wrote - I read you something from 1901, and there was a purpose into that. Because I think that if we talk about building subways, there is - in 1901, people decided that in order to make proper provision for the large number of electric cables and gas and water pipes and sewers which lie beneath the streets of the city, they were going to create a gallery alongside of the tunnel -the rapid transit subway, to place these utilities, so one would never have to dig again.

FLATOW: That makes sense to me.

Mr. HORODNICEANU: Right? Right.

FLATOW: Right. Look how well that's worked out. (Laughing)

Mr. HORODNICEANU: So the point is that, then, this was just moved aside because there was a certain cost associated with that.

FLATOW: Right.

Mr. HORODNICEANU: We could have amortised, of course, a thousand times over. And, in fact...

FLATOW: Right. Always...

Mr. HORODNICEANU: ...we have failed to create that going forward as well. So...

FLATOW: Absolutely. All that digging...

Mr. HORODNICEANU: ...they keep cutting our streets.

FLATOW: Let me ask you, Clifton Hood, in a few minutes we have left, was it a big hit when it first opened? Did the people readily get on and travel on it?

Prof. HOOD: The very first day the subway opened, the paper's headline is the birth of the subway crush.

FLATOW: Wow. Right from day one.

Prof. HOOD: People didn't think - yeah. And the planned maximum capacity for the subway was exceeded within two or three years. Nobody had any idea how popular it would be. And the real thing that was different is that New York has express and local service, and only the Broad Street Line in Philadelphia has that. And that is what enabled the subway to have the impact it did in changing the physical landscape.

Manhattan was really only developed to about - the Upper West Side, the Upper East Side. And it unleashes this massive construction boom, but also there are so many more people taking the subway, and they can ride it so much longer.

The other thing that's really striking is that - in doing the research for this book, I discovered that there are all sorts of love songs that were written about the subway in the first five or six years. This is Tin Pan Alley. And there was a song about a boy and a girl meeting in Lower Manhattan, being pushed into each other's arms and falling in love by Harlem, the saying used to be 15 minutes to Harlem.

And so it really was a phenomenon. And we think of it as being outdated today, but for 1904, for 190- 10, well before airplanes, this was really technologically modern. It was a big deal in that way too. People would go down in it just for sightseeing, to see something.

FLATOW: Do you think people really think the subways are outdated? Here in New York, I don't think people, you know, it's still - people depend on it. Jimmy Breslin was right 20 years ago when I asked him that question.

Prof. HOOD: Oh, he was. He was. But I don't think we conceive of it as being - it's not that the subways are outdated, but I think the operating equipment isn't viewed as being - you know, we think of computers now. We think of the Internet as being the latest thing.

FLATOW: Right.

Mr. HORODNICEANU: In 1900, the subway was the latest thing.

FLATOW: Mm-hmm. And they'll - they're going to be modernized? Michael...

Prof. HOOD: Yeah.

FLATOW: there any way to upgrade them to 21st century?

Mr. HORODNICEANU: Well, we are trying to build the stations to be the 21st century. And I think the trains and the automatic train control will show up. And there is, clearly, a push to more automation, to technology advances on the subway systems. So the new cars are actually being built with much more technology advanced systems, and that's going to be the trend toward the 21st century. But we are trying to build our own stations to match the 21st century technology.

Prof. HOOD: Well, one of the great changes, the last five or 10 years has been that you're - you can be in a subway station and there will be a sign telling you that the next train will be five or 10 minutes away. And that's just a remarkable convenience for passengers.

FLATOW: All right. And we've run out of time. I want to thank Michael Horodniceanu. He's president of the MTA Capital Construction Company. Clifton Hood, author of "722 Miles: The Building of the Subways and How They Transformed New York." Gentlemen, thank you. Thank you very, very much for taking the time to be with us today.

Mr. HORODNICEANU: Thank you.

Prof. HOOD: Thank you.

FLATOW: That's all the time we have today.

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