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karma-dharma

a-rai (Civil/Environmental)

(OP)

30 Apr 23 14:41

I have a few questions.

Ancient Rome's population peaked at around a million people. London in the 19th century was the first city to surpass that. According to the UN's data booklet, The World's Cities in 2018, the number of cities with at least 1 million inhabitants were 548. Tokyo was the most populous with more than 37 million people.

Consider the amount of structures and infrastructure (electrical and plumbing systems, etc.) built in a relatively short period of time. What will happen when everything starts to fail? Will we try to repair what is irreparable? In that hopeless state of things, will we hop into airplanes or spaceships to move to another plot of land or planet? Will we rebuild everything in our new home? What will happen to our old one? Will it be the post-apocalyptic world portrayed in films of the past? Will it be a laboratory for military personnel to retrieve images of mushroom clouds? In the new world, will we use the same plans or make them better? Are we all Bill Murray in Groundhog Day? Are we the end product of our own creation? Did the psyche bring the cycle? Is this not the definition of insanity?

Are you ready? I'm just curious...

zeusfaber (Military) · Answer 1 · 2023-04-30 16:52:57

As a student in London in the 1980s, I lived in a succession of buildings built in the late 19th Century with a design life of 100 years (without anticipating the maintenance neglect consequent upon two periods of total war). I drove past one of them last summer and was mildly surprised (no, considering the state we'd left it in, jaw-droppingly astonished) to see it still there.

It's simply not the end when everything begins to fail. Old buildings (and their infrastructure) will stagger on for decades provided their owners think there's value in maintaining them or if there's a ready enough supply of tenants willing to swap a lot of dilapidation for an almost-affordable rent. Buildings between those extremes get knocked down earlier. It's the breadth of this spectrum that spreads the burden of renewing old housing stock and which cushions the shock.

IRstuff (Aerospace) · Answer 2 · 2023-04-30 23:34:55

The Palace of Versailles was built in 1623, mostly, and is both standing and operating, as a museum, with way more people roaming around than even at the height of its prominence. So, that's 400 years, this year, but admittedly in a tectonically stable part of the world with relatively benign weather.

But, the issue isn't really an issue; not all of the infrastructure collapses at the same time, and we either find the money to rebuild, or we abandon and move elsewhere. It's not like we're living cheek to jowl EVERYWHERE; there's still plenty of space in the world. Additionally, most buildings will continue to survive, so long as there aren't natural disasters like earthquakes or tsunamis, etc. Roads are a different matter, since there's tons of wear and tear, and we've deferred the repairs on lots of roads, so we might need to do like Schwarzenegger and repair our local streets ourselves.

TTFN (ta ta for now)
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MortenA (Petroleum) · Answer 3 · 2023-05-01 11:55:54

@a-rai, thats a very un-engineer like question. Of course things fails and run out of use full life span - but then its repaired or replaced! Forthunately not everything fails at the same time - and somethimes politicians even put money aside for this

Why should repairs or replacement be impossible? That makes no sense.

--- Best regards, Morten Andersen

a-rai (Civil/Environmental) · Answer 4 · 2023-05-01 12:56:08

The Palace of Versailles doesn't have the metro under it.

A product recall exemplifies systemic failure within a time frame. Large-scale urban projects are typically built in one go. Carbon copy bridges of yesteryear will show signs of distress simultaneously.

How many parts of structures and infrastructure are inaccessible? The materials are left to their nature and struggle with time.

MortenA, which one? smile

phamENG (Structural) · Answer 5 · 2023-05-01 13:07:45

Quote (a-rai)
Carbon copy bridges of yesteryear will show signs of distress simultaneously.

Not so much. Just because the design is the same doesn't mean a) they were built exactly the same b) maintained exactly the same or c) exposed to the same things.

Differences in loading will create differences in wear, different environmental factors (even micro-climate factors like how much sun hits the deck) will change the stresses and damage caused. A bridge of identical design in New Jersey and Georgia will probably not last as long in New Jersey if the maintenance is the same due to heavier use of de-icing salts. Two bridges in New Jersey a mile apart - one near a manufacturing plant and one serving a primarily residential area. The manufacturing plant will have significantly more truck traffic and greater wear. Two bridges a quarter mile apart with similar traffic but with a city border between them - one city invests in maintaining a bridge and the other doesn't. One will fail earlier than the other.

We had a huge building boom and, in many cases, a large period of neglect. That's absolutely true. And it's true that a lot of it will age into obsolescence in a shorter period than is comfortable. But your use of hyperbole does nothing to engage intelligent discussion on the topic. Post-apocalyptic films of the past? Really? The level of apathy required to end up there is a bit hard to imagine, even if many governments are increasingly unable to function properly.

a-rai (Civil/Environmental) · Answer 6 · 2023-05-02 02:39:24

phamENG, I'm not interested in discussion. I'd simply like to know what you all think about this. There seems to be divergence of opinion already. IRstuff thinks the issue isn't an issue whereas you acknowledge it as such. It would be great if others chime in to understand what the engineering community leans toward. Perhaps then the replacement of the sewage system of an urban agglomeration, for example, could be discussed.

SWComposites (Aerospace) · Answer 7 · 2023-05-02 03:05:10

RE: karma-dharma

SWComposites (Aerospace) 2 May 23 03:05

Your premise is completely wrong.

phamENG (Structural) · Answer 8 · 2023-05-02 11:49:45

Quote (a-rai)
I'm not interested in discussion. I'd simply like to know what you all think about this.

Umm...what?

drawoh (Mechanical) · Answer 9 · 2023-05-02 16:28:54

a-rai,

Buildings last a very long time when they are useful and people care for them.

Ancient Rome's problem is that they lost control of their empire, their military, and north Africa where all their food came from. The population dropped and they stopped caring for their buildings and infrastructure. Medieval Bagdhad's problem is that Hulagu Khan captured the place and killed everyone.

--
JHG

ACtrafficengr (Civil/Environmental) · Answer 10 · 2023-05-02 20:11:23

I don't think the problem is whether we can maintain individual bridges, buildings, etc. It's how we will pay for maintaining all of them.

One big area of concern is the amount of civil infrastructure - streets, water, sanitary sewer and stormwater pipes, treatment plants, fire and police stations, schools, and so on - needed to support suburban lifestyles. Compare the revenue they generate to the maintenance costs. I strongly suspect the ratio will be less than one. How much longer will this be sustainable? Will we have to triage neighborhoods? If so, how?

This chart represents the change in infrastructure per capita in Lafayette, Louisiana before and after suburbanization. Yes, now we have more durable materials than clay pipe and tar-macadam, but it still shows an increased burden in infrastructure costs per household.

My glass has a v/c ratio of 0.5

Maybe the tyranny of Murphy is the penalty for hubris. - http://xkcd.com/319/

dik (Structural) · Answer 11 · 2023-05-02 21:46:07

act... I didn't realise there was that huge escalation... likely representative of everywhere. thanks...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

a-rai (Civil/Environmental) · Answer 12 · 2023-05-03 04:09:09

Our cities are a big bang of construction. A few Chinese built 57 stories in 19 days. Ask yourself what China builds in 365. According to the Council on Tall Buildings and Urban Habitat, 14 cities now have more than 100 buildings at least 150 m (492 ft) tall. Nobody maintains the foundation of a skyscraper. Consequently, what goes up must come down. Earthquakes aside, time is a disaster in the making. It will trigger a domino effect.

phamENG (Structural) · Answer 13 · 2023-05-03 04:19:29

Where's a Billy goat when you need one?

IRstuff (Aerospace) · Answer 14 · 2023-05-03 04:21:59

Quote:
Nobody maintains the foundation of a skyscraper.

What maintenance are you referring to? There are lots of buildings in excess of 200 years old that probably haven't anyone maintain their foundations.

TTFN (ta ta for now)
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dik (Structural) · Answer 15 · 2023-05-03 05:35:59

Most modern architecture will be functionally obsolete in 200 years.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

TenPenny (Mechanical) · Answer 16 · 2023-05-03 20:05:19

"Consider the amount of structures and infrastructure (electrical and plumbing systems, etc.) built in a relatively short period of time. What will happen when everything starts to fail?"

We are already at the point where perfectly good buildings are destroyed because it is economically 'better' to build something different.

The failure of infrastructure is going full speed, bridges are falling down due to no maintenance, for example.

I think what will happen is that the infrastructure will need replacing and will consume a higher and higher portion of budgets, but everyone will simply carry on as if this is fine.

CWB1 (Mechanical) · Answer 17 · 2023-05-03 22:43:08

I must be missing something as a history and architecture buff bc stateside our cities look nothing like they did a century ago. Popular landmarks have survived but most everything else is replaced after a half-century or so.

a-rai (Civil/Environmental) · Answer 18 · 2023-05-04 04:10:30

CWB1, 13 years ago CBRE (the world's largest commercial real estate services and investment firm) had this to say about Manhattan: the average larger midtown commercial building is 57 years old; the average midtown south one is 92; and downtown it's 63. This is based on buildings measuring over 75,000 square feet in midtown south and downtown, and over 150,000 square feet in midtown. The majority of these buildings - 55.1% in midtown, 93.7% in midtown south and 55.5% in downtown - are over 50. The Bloomberg administration's PlaNYC stated the following: by 2030, almost 70% of the power plants that supply the city will be more than 50 years old.

More recently, New York City's strategic plan has this: much of the city's infrastructure was built a century ago and has suffered from historic disinvestment, neglect, and poor maintenance. On average, our sewer mains are 85 years old, water mains are 70 years old, and the electric grid dates back to the 1920s.

a-rai (Civil/Environmental) · Answer 19 · 2023-05-04 11:13:55

Here is a picture of New York City in 1928. Notice the Woolworth Building. It was the tallest building in the world in the 1920s. The Chrysler Building was completed 2 years after this photo was taken, and the Empire State Building became the tallest structure of any kind 1 year after that.

a-rai (Civil/Environmental) · Answer 20 · 2023-05-04 11:57:19

Here is a recent image for comparison.

BrianPetersen (Mechanical) · Answer 21 · 2023-05-04 13:35:29

120 years ago, planners were worried that the explosion of population and horse drawn carriages were going to bury cities in poop.

We've moved on. We will move on again.

IRstuff (Aerospace) · Answer 22 · 2023-05-05 02:47:43

So, 123 years later, the Woolworth Building is still a functional and functioning building and part of it has been repurposed as residences.

And, the comparison picture belies your complaint; older buildings didn't get abandoned, they were torn down to build more suitable buildings. Such is the way of life.

TTFN (ta ta for now)
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a-rai (Civil/Environmental) · Answer 23 · 2023-05-05 07:41:12

IRstuff, imagine yourself atop this hill in Shenzhen soon after graduating. You wouldn't retire before seeing that sprawl. In fact, you'd still have to work for a decade or so. The city is like a building. Think of it as the Paris of Versailles. When the time comes to tear it down, as you said, where will everyone go?

CWB1 (Mechanical) · Answer 24 · 2023-05-05 13:02:03

Residents will move into the new buildings that replace them, the same as most cities. When necessary we'll also do like we've done in Detroit, Youngstown OH, and others and simply not replace infrastructure if not needed.

SWComposites (Aerospace) · Answer 25 · 2023-05-05 14:47:00

a-rai - what is the point of your questions??

IRstuff (Aerospace) · Answer 26 · 2023-05-05 15:13:57

Quote:
When the time comes to tear it down, as you said, where will everyone go?

I never said nor implied that an entire city would get torn down. Buildings get fixed or replaced.

TTFN (ta ta for now)
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a-rai (Civil/Environmental) · Answer 27 · 2023-05-06 10:24:07

SWComposites, what do you mean? Why am I asking or what am I asking?

a-rai (Civil/Environmental) · Answer 28 · 2023-05-07 10:21:32

Wise are those who question...

The protagonist below embodies the world of construction. If you think it should stop, you see an issue. That's all.

Aesur (Structural) · Answer 29 · 2023-05-09 23:08:26

Quote (a-rai)
A few Chinese built 57 stories in 19 days.

I believe you mean, erected buildings in 19 days, there is a big difference in erection time and construction time. These buildings from what I recall were assembled as modules over the coarse of months/years as was the foundation. They just shifted where the "time went".

Quote (a-rai)
phamENG, I'm not interested in discussion. I'd simply like to know what you all think about this.

Did not phamENG provide his thoughts here? Asking for someones thoughts is the same as discussing it, you can't ask for a thought, disagree but then shut out the person before they can provide context to their thoughts - that is called American politics :P.

A good current case study for not maintaining a city and people leaving is Detroit, but since we aren't encouraged to have a discussion here, I'll let you go research it for yourself.

IRstuff (Aerospace) · Answer 30 · 2023-05-10 03:24:44

Quote:
If you think it should stop, you see an issue.

Why do you think it should stop? Aren't there an every increasing number of people in the world? Are they supposed to live and work on the streets without housing and workplaces?

And if someone moves from, say, San Francisco to Boise, are they supposed to live and work on the streets without housing and workplaces?

Or are you advocating not allowing for more kids and not allowing anyone to move to a different city?

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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a-rai (Civil/Environmental) · Answer 31 · 2023-05-10 08:41:11

My dictionary defines engineering as the discipline dealing with the art or science of applying scientific knowledge to practical problems and therefore the point of an engineer is using scientific knowledge to solve practical problems. In the eyes of the engineering community, the identification of a problem is the first step towards a solution. Aesur, I won't discuss it, but you can. I'll just observe, like that orange circle right above you. wink

Pardon my frequent use of images. Was it Wordsworth who said a picture is worth a thousand words? Take a good look at this metropolitan aerial. I say a picture is worth a thousand worlds.

ACtrafficengr (Civil/Environmental) · Answer 32 · 2023-05-10 20:09:56

Quote (a-rai)
My dictionary defines engineering as the discipline dealing with the art or science of applying scientific knowledge to practical problems

I was intrigued to find out yesterday that engineering predates science: Building a Cathedral without Science or Mathematics: The Engineering Method Explained

My glass has a v/c ratio of 0.5

Maybe the tyranny of Murphy is the penalty for hubris. - http://xkcd.com/319/

IRstuff (Aerospace) · Answer 33 · 2023-05-10 21:39:30

Quote:
Pardon my frequent use of images. Was it Wordsworth who said a picture is worth a thousand words? Take a good look at this metropolitan aerial. I say a picture is worth a thousand worlds.

You continue to make assertions with no point to them. What exactly is wrong in the image, and what do you think should be in its place?

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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GregLocock (Automotive) · Answer 34 · 2023-05-11 00:23:43

a-rai posted a picture of a success story. That's nice. Note the blue skies, not too much pollution. There's a freeway into the CBD for commuters. There appear to be zoning restrictions so that houses aren't intermingled with industrial facilities. But as many people have written, a picture is just a picture.

Cheers

Greg Locock

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a-rai (Civil/Environmental) · Answer 35 · 2023-05-11 02:18:10

GregLocock, you seem to have watched THC's Tokyo Legacy...

GregLocock (Automotive) · Answer 36 · 2023-05-11 03:04:45

Subtext, without an explanation sometimes a picture is just wallpaper.

Cheers

Greg Locock

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a-rai (Civil/Environmental) · Answer 37 · 2023-05-11 09:10:20

GregLocock, the ellipsis omitted the fact it doesn't exist. Your vision of a success story is based on looking at wallpaper (as you put it). There is no historical precedent for such a large city. Take a closer look at Tokyo's walls and use judgement to realize the magnitude of replacing structures and substructures.

MedicineEng (Industrial) · Answer 38 · 2023-05-11 09:13:30

Sorry, I'm lost.
What is this discussion about?

GregLocock (Automotive) · Answer 39 · 2023-05-11 21:32:02

Random whingeing disguised as deep thought. Sophomoric pub talk.

Cheers

Greg Locock

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Aesur (Structural) · Answer 40 · 2023-05-11 22:23:40

Quote (MedicineEng)
Sorry, I'm lost.
What is this discussion about?

I'm guessing the OP took a philosophical class recently or just wants to confuse us with random statements.

Just Some Nerd (Structural) · Answer 41 · 2023-05-12 02:44:36

OP, what leads you to believe every major city in the world has put no thought into long-term city planning?

----------------------------------------------------------------------

Why yes, I do in fact have no idea what I'm talking about

IRstuff (Aerospace) · Answer 42 · 2023-05-12 04:48:17

Quote:
There is no historical precedent for such a large city. Take a closer look at Tokyo's walls and use judgement to realize the magnitude of replacing structures and substructures.

Again, pointless; there is no historical precedence for that level population, and they have to live and work somewhere.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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a-rai (Civil/Environmental) · Answer 43 · 2023-05-12 06:57:16

Just Some Nerd, I don't believe that at all. In fact, here is a picture of long-term city planning - build and they will come - in the guise of cookie-cutter apartment houses. In the long run it led to the original post.

Random is reporting and deleting my previous post because I called this thread entertaining. That's random.

Answer 44

[Post Deleted]

dik (Structural) · Answer 45 · 2023-05-12 17:17:54

Quote (OP, what leads you to believe every major city in the world has put no thought into long-term city planning?)

I've seen a lot of examples of 'bad planning' as well as changes to planning schemes that have been modified over time. Toronto, for example put their airport 'in the middle of nowhere, and eventually allowed housing to be constructed in the area. Homeowners complained about the noise and now the airport is closed during the night time. There are lots of this type of example.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

ACtrafficengr (Civil/Environmental) · Answer 46 · 2023-05-12 18:15:36

I suspect A-Rai is hung up on the replacement costs, and what that would do to an economy if all the bills came due at once. I think they are missing the point that barring a massive natural disaster or abysmal planning, proper preventive maintenance can prevent that.

This deterioration curve is for pavement, but a lot of other infrastructure would be similar. Proper preventive and corrective maintenance will prolong the lifespans of most facilities. The keys are planning it and funding it so you can stay near the top of the curve for as long as possible.

Some funding sources have adverse incentives. They will fund rehab or reconstruction, but not preventive maintenance. For example, the Federal Highway Administration will pay for 80% of a bridge replacement project. Perhaps they should pay for bridge cleaning and painting instead. NY State distributes highway funding to municipalities, but insists it goes to projects with ten year minimum design lives. Preventive maintenance like surface treatments have the lowest lifetime cost, but need to be reapplied more often than that.

And that's why I would take a long look at any candidate that held a ribbon cutting for a crack sealing project.

My glass has a v/c ratio of 0.5

Maybe the tyranny of Murphy is the penalty for hubris. - http://xkcd.com/319/

dik (Structural) · Answer 47 · 2023-05-12 18:25:50

The red one is like the Winnipeg model. They have done very little or poor maintenance over the decades, and I think it has caught up with them.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

Aesur (Structural) · Answer 48 · 2023-05-12 20:49:17

@ACtrafficengr - the point I get from that pavement maintenance curve is that roads are designed very poorly, only 13 year expected life span? No wonder I see local roads in a continuous re-build state, starting at one end, getting to the other end in time to start back over. Any idea how much more expensive it would be to say design the road for a 50 year life span, or more, I would expect it would probably be less than lifetime maintenance on asphalt.

a-rai (Civil/Environmental) · Answer 49 · 2023-05-13 03:05:59

Bills aren't what I'm getting at. Failures all coming at once are, regardless of disasters. Nobody maintains the tubes of the underground, for example. The structure of a subway system is mostly completed around the same time (yester-year) and will eventually collapse. Printing money is useless.

IRstuff (Aerospace) · Answer 50 · 2023-05-13 17:23:40

Quote:
The structure of a subway system is mostly completed around the same time (yester-year) and will eventually collapse.

You are seriously confused, as with most non-engineers; reliability is not a timer, it's a random event. Just like sinkholes do not appear everywhere all at once, unless you do something stupid; Buildings, even on the same block will have different characteristics, due to the design, construction, and environment conditions.

A good example is the SF Millennium Tower, which started leaning even before it was completed, while none of the surrounding buildings had this level of issue.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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Just Some Nerd (Structural) · Answer 51 · 2023-05-15 02:55:38

It would be pretty wild to see a world where everything immediately collapses once it exceeds its design life tongue

----------------------------------------------------------------------

Why yes, I do in fact have no idea what I'm talking about

a-rai (Civil/Environmental) · Answer 52 · 2023-05-15 13:13:50

What's the design life of the Holland Tunnel? It opened in 1927 (see picture supra). I wouldn't cross it, even if ACtrafficengr paid the toll. That thing actually flooded about a decade ago, and it's only a decade older than its neighbor the Lincoln Tunnel.

ACtrafficengr (Civil/Environmental) · Answer 53 · 2023-05-15 13:29:01

@Aesur, That's just a representative graph, and most roads last longer than that. The point is preventive maintenance has a much lower lifecycle cost than deferred maintenance.

Also, the X axis should really be in the number of truck axles crossing it, but that's pretty hard for most people to visualize.

Actual life depends mostly on weather, amount of truck traffic, pavement design, drainage, subsoil type, etc. Like any engineered product, it's a balancing act between initial costs, maintenance costs, and user costs.

My glass has a v/c ratio of 0.5

Maybe the tyranny of Murphy is the penalty for hubris. - http://xkcd.com/319/

IRstuff (Aerospace) · Answer 54 · 2023-05-15 23:47:09

Quote:
That thing actually flooded about a decade ago, and it's only a decade older than its neighbor the Lincoln Tunnel.

So, what, you don't cross either tunnel? Is the Holland Tunnel collapsed? What was the cause of the flood? Have there been no years with the same conditions as the year of the flood?

TTFN (ta ta for now)
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a-rai (Civil/Environmental) · Answer 55 · 2023-05-18 17:05:17

IRstuff, the idea is to see that the Holland Tunnel is 96 years old and flooded when it was 85.

NY State's Department of Transportation published Highway Bridge Data for 2022. In NY City, 105 bridges were considered poor/structurally deficient. In total, 1 was from the 1850s; 8 were from the 1860s; 2 from the 1870s; 18 the 1880s; 12 the 1890s; 93 the 1900s; 61 the 1910s; 54 the 1920s; 207 the 1930s; 111 the 1940s; 221 the 1950s; 338 the 1960s; 75 the 1970s; 44 the 1980s; 45 the 1990s; 77 the 2000s; 83 the 2010s; and 23 since 2020. Note that there are more bridges from the 1900s than from any decade after the 1960s. There are 1,126 bridges that are over 53 years old. This represents 76.44% of all bridges.

NY City's Department of Transportation published Bridges and Tunnels Annual Condition Report annually until 2020. For some reason, 2021 and 2022 are not available. In 2020, it operated 799 bridges, 4 vehicular tunnels and 53 culverts. Using 4 condition ratings (poor, fair, good and very good), 386 structures were rated fair and correspond to 48.37% of all bridges. These also correspond to 60.82% of total deck area and 65.13% of all bridge spans. Not good. The report has this: during 2020, Manhattan had the highest percentage of bridge structures rated fair - 58.56% - as well as the lowest percentage of bridge structures rated good - 25.97%. Bridges included in this report are the Brooklyn (1883), Manhattan (1909), Williamsburg (1903), Queensboro (1909), High (1848), Broadway (1960), Grand Street (1902), Hell Gate (1917), Macombs Dam (1895), Madison Avenue (1910), Pulaski (1954), Rikers Island (1966) and Roosevelt Island (1955).

The Metropolitan Transportation Authority operates bridges and tunnels on the Metro-North Railroad, Long Island Railroad and subway systems in addition to 7 bridges and 2 tunnels. These are the Verrazzano-Narrows Bridge (1964), Triborough Bridge (1936), Bronx-Whitestone Bridge (1939), Throgs Neck Bridge (1961), Henry Hudson Bridge (1936), Cross Bay Veterans Memorial Bridge (1970), Marine Parkway-Gil Hodges Memorial Bridge (1937), Brooklyn-Battery Tunnel (1950) and Queens-Midtown Tunnel (1940).

The Port Authority of NY and NJ operates the Holland Tunnel (1927), Lincoln Tunnel (1937), George Washington Bridge (1931), Bayonne Bridge (1931), Outerbridge Crossing (1928) and Goethals Bridge (1928). The latter (of Gotham City fame) in Elizabeth, NJ was replaced in 2017/18.

Additionally, the NYC Department of Parks and Recreation, NYC Department of Environmental Protection, and Amtrak operate other bridges and tunnels.

Some other examples are Carroll Street Bridge (1889), Spuyten Duyvil Bridge (1900), Pelham Bridge (1908), Borden Avenue Bridge (1908), Wards Island Bridge (1951), Park Avenue Bridge (1956), Arthur Kill Vertical Lift Bridge (1959), Alexander Hamilton Bridge (1963), Joralemon Street Tunnel (1908), Uptown and Downtown Hudson Tubes (1908/09), North River Tunnels (1910), East River Tunnels (1910), 60th Street Tunnel (1920), Park Avenue Tunnel (1834) and Viaduct (1919).

a-rai (Civil/Environmental) · Answer 56 · 2023-05-19 00:44:29

I'd like to clarify that the previous post refers to New York City only. Bridges and tunnels serving the rest of the New York-Newark urban agglomeration of 18,819,000 (as per the UN's data booklet cited earlier) are not included.

Sparweb (Aerospace) · Answer 57 · 2023-05-20 01:16:23

The notion that anything will fail, all at once, at the end of its life, has been a subject of discussion and debate and even poetry for a LONG time. Practical people can figure this stuff out. Logic is logic. That's all I say.

It's a fun read, for those so inclined. Actually it's way more fun in voice. Start your next Zoom meeting with this.

Quote (Oliver Wendell Holmes)

Have you heard of the wonderful one-hoss shay,
That was built in such a logical way
It ran a hundred years to a day,
And then, of a sudden, it -- ah, but stay,
I'll tell you what happened without delay,
Scaring the parson into fits,
Frightening people out of their wits, --
Have you ever heard of that, I say?
Seventeen hundred and fifty-five.
Georgius Secundus was then alive, --
Snuffy old drone from the German hive.
That was the year when Lisbon-town
Saw the earth open and gulp her down,
And Braddock's army was done so brown,
Left without a scalp to its crown.
It was on the terrible Earthquake-day
That the Deacon finished the one-hoss shay.
Now in building of chaises, I tell you what,
There is always somewhere a weakest spot, --
In hub, tire, felloe, in spring or thill,
In panel, or crossbar, or floor, or sill,
In screw, bolt, thoroughbrace, -- lurking still,
Find it somewhere you must and will, --
Above or below, or within or without, --
And that's the reason, beyond a doubt,
A chaise breaks down, but does n't wear out.
But the Deacon swore (as Deacons do,
With an "I dew vum," or an "I tell yeou")
He would build one shay to beat the taown
'N' the keounty 'n' all the kentry raoun';
It should be so built that it could n' break daown:
"Fur," said the Deacon, "'t 's mighty plain
Thut the weakes' place mus' stan' the strain;
'N' the way t' fix it, uz I maintain,
Is only jest
T' make that place uz strong uz the rest."
So the Deacon inquired of the village folk
Where he could find the strongest oak,
That could n't be split nor bent nor broke, --
That was for spokes and floor and sills;
He sent for lancewood to make the thills;
The crossbars were ash, from the straightest trees,
The panels of white-wood, that cuts like cheese,
But lasts like iron for things like these;
The hubs of logs from the "Settler's ellum," --
Last of its timber, -- they could n't sell 'em,
Never an axe had seen their chips,
And the wedges flew from between their lips,
Their blunt ends frizzled like celery-tips;
Step and prop-iron, bolt and screw,
Spring, tire, axle, and linchpin too,
Steel of the finest, bright and blue;
Thoroughbrace bison-skin, thick and wide;
Boot, top, dasher, from tough old hide
Found in the pit when the tanner died.
That was the way he "put her through."
"There!" said the Deacon, "naow she'll dew!"
Do! I tell you, I rather guess
She was a wonder, and nothing less!
Colts grew horses, beards turned gray,
Deacon and deaconess dropped away,
Children and grandchildren -- where were they?
But there stood the stout old one-hoss shay
As fresh as on Lisbon-earthquake-day!
EIGHTEEN HUNDRED; -- it came and found
The Deacon's masterpiece strong and sound.
Eighteen hundred increased by ten; --
"Hahnsum kerridge" they called it then.
Eighteen hundred and twenty came; --
Running as usual; much the same.
Thirty and forty at last arrive,
And then come fifty, and FIFTY-FIVE.
Little of all we value here
Wakes on the morn of its hundreth year
Without both feeling and looking queer.
In fact, there's nothing that keeps its youth,
So far as I know, but a tree and truth.
(This is a moral that runs at large;
Take it. -- You're welcome. -- No extra charge.)
FIRST OF NOVEMBER, -- the Earthquake-day, --
There are traces of age in the one-hoss shay,
A general flavor of mild decay,
But nothing local, as one may say.
There could n't be, -- for the Deacon's art
Had made it so like in every part
That there was n't a chance for one to start.
For the wheels were just as strong as the thills,
And the floor was just as strong as the sills,
And the panels just as strong as the floor,
And the whipple-tree neither less nor more,
And the back crossbar as strong as the fore,
And spring and axle and hub encore.
And yet, as a whole, it is past a doubt
In another hour it will be worn out!
First of November, 'Fifty-five!
This morning the parson takes a drive.
Now, small boys, get out of the way!
Here comes the wonderful one-horse shay,
Drawn by a rat-tailed, ewe-necked bay.
"Huddup!" said the parson. -- Off went they.
The parson was working his Sunday's text, --
Had got to fifthly, and stopped perplexed
At what the -- Moses -- was coming next.
All at once the horse stood still,
Close by the meet'n'-house on the hill.
First a shiver, and then a thrill,
Then something decidedly like a spill, --
And the parson was sitting upon a rock,
At half past nine by the meet'n-house clock, --
Just the hour of the Earthquake shock!
What do you think the parson found,
When he got up and stared around?
The poor old chaise in a heap or mound,
As if it had been to the mill and ground!
You see, of course, if you're not a dunce,
How it went to pieces all at once, --
All at once, and nothing first, --
Just as bubbles do when they burst.
End of the wonderful one-hoss shay.
Logic is logic. That's all I say.

a-rai (Civil/Environmental) · Answer 58 · 2023-05-20 03:29:25

Logic is this:

If a bridge is a bubble and bubbles burst,
you're asking for trouble if you build the first
and quadruple and double to quench your thirst;
you'll collect the rubble when first comes to worst.

That's my New Yo'k say.

IRstuff (Aerospace) · Answer 59 · 2023-05-20 05:52:32

Quote:
That thing actually flooded about a decade ago, and it's only a decade older than its neighbor the Lincoln Tunnel.

Quote:
the idea is to see that the Holland Tunnel is 96 years old and flooded when it was 85.

By this argument, the Lincoln Tunnel should have collapsed by now as well, and yet, both are still functional. You cannot predict the exact time of a total failure; such is the nature of random events.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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verymadmac (Mechanical) · Answer 60 · 2023-05-20 10:19:45

Most things can be re-lifed if there is sufficient motivation although being designed with generous margins helps, but then if it wasn't someone would have had reason to replace upgrade it already.

Since Sparweb beat me to quoting the One Horse Shay (did you first read it due to its reference in one of J. E. Gordon's books?), I will post pics from when they let the public (me included) walk through the Thames tunnel (2011). The original Thames tunnel started 1825 finished 1843, it was relined ~ 2010 (complete with historical arches and detail work left distinguishable) as part of the overground upgrades.

dik (Structural) · Answer 61 · 2023-05-20 14:13:31

Quote (Most things can be re-lifed if there is sufficient motivation)

...as the pavement condition index above illustrates, there may be a price to do that. If left too long, the cost may be prohibitive, without proper maintenance.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

Sparweb (Aerospace) · Answer 62 · 2023-05-20 16:14:24

Quote (verymadmac)
Since Sparweb beat me to quoting the One Horse Shay (did you first read it due to its reference in one of J. E. Gordon's books?)

Correct!

a-rai (Civil/Environmental) · Answer 63 · 2023-05-21 07:37:35

verymadmac, I take it you're a fan of post-apocalyptic films. Picture this:

A section of the NYC subway system collapses with or without a train underneath. Notified of the event, authorities scramble to stop all service, close the system and send a team of engineers to evaluate the safety conditions of the remaining tunnels scattered throughout the five boroughs. Urged to hasten their investigation, the experts haven't a clue as to how to go about assessing the structural integrity of the tubes. Meanwhile, chaos is widespread as millions of people are left without transportation. Urged further to conclude their findings, the investigators have 2 options; delay or make believe all is good at the risk of a future collapse. Needless to say, delay won't bring a risk-free conclusion.

This can happen in any one of the nearly 200 subway systems in the world, prompting other cities to do something (nothing) about it. Is this plausible or is it groundhog-wash?

GregLocock (Automotive) · Answer 64 · 2023-05-21 22:52:26

"the experts haven't a clue as to how to go about assessing the structural integrity of the tubes" Do you know how remarkably stupid that sentence sounds?

Cheers

Greg Locock

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a-rai (Civil/Environmental) · Answer 65 · 2023-05-22 01:42:23

RE: karma-dharma

a-rai (Civil/Environmental)

(OP)

22 May 23 01:42

Could you elaborate?

dik (Structural) · Answer 66 · 2023-05-22 02:11:43

With many types of construction, you can make periodic inspections to look for signs of distress. For some types of construction, there may be no advance warning of a potential collapse. There is a good chance the collapse may be brought about by other issues.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

a-rai (Civil/Environmental) · Answer 67 · 2023-05-22 14:19:26

Right, so do like the Beatles and let it be.

After introducing Holmes' poem, Gordon wrote the following:

The entire physical world is most properly regarded as a great energy system: an enormous marketplace in which one form of energy is for ever being traded for another form according to set rules and values. That which is energetically advantageous is that which will sooner or later happen. In one sense a structure is a device which exists in order to delay some event which is energetically favoured. It is energetically advantageous, for instance, for a weight to fall to the ground, for strain energy to be released - and so on. Sooner or later the weight will fall to the ground and the strain energy will be released; but it is the business of a structure to delay such events for a season, for a lifetime or for thousands of years. All structures will be broken or destroyed in the end - just as all people will die in the end. It is the purpose of medicine and engineering to postpone these occurrences for a decent interval.

Alas, the plan is Times Square becoming the Great Pyramid and vice versa and so on... Is this a photograph?

dik (Structural) · Answer 68 · 2023-05-22 14:55:37

Quote (Right, so do like the Beatles and let it be.)

but monitor as best you can... and check for other signs such as water infiltration, etc. There are often indications that things are amiss before they happen... not always, but often.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

IRstuff (Aerospace) · Answer 69 · 2023-05-22 15:08:11

Quote:
This can happen in any one of the nearly 200 subway systems in the world, prompting other cities to do something (nothing) about it. Is this plausible or is it groundhog-wash?

So, what? Did you pay extra to ensure that that house you live in will last 1000 years? Are you paying for annual inspections of your house to ensure it won't collapse while you sleep?

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

GregLocock (Automotive) · Answer 70 · 2023-05-22 22:35:17

"the experts haven't a clue as to how to go about assessing the structural integrity of the tubes" Well, then you've got the wrong experts.

Cheers

Greg Locock

New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

Answer 71

[Post Deleted]

CWB1 (Mechanical) · Answer 72 · 2023-05-23 01:00:18

Testing infrastructure is easy and common, its just not always cheap.

dik (Structural) · Answer 73 · 2023-05-23 16:50:49

Quote (I suspect he's an expert in mud-brick suspension bridges)

You'd have a tough time convincing me of even that...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

Just Some Nerd (Structural) · Answer 74 · 2023-05-24 00:13:03

I'm having a hard time distinguishing what we're even talking about anymore...if someone could put out a clear statement to argue over that would be great.

----------------------------------------------------------------------

Why yes, I do in fact have no idea what I'm talking about

phamENG (Structural) · Answer 75 · 2023-05-24 02:42:52

RE: karma-dharma

phamENG (Structural) 24 May 23 02:42

The earth is flat.

Now...go!

a-rai (Civil/Environmental) · Answer 76 · 2023-05-24 03:30:15

Just Some Nerd, where is engineering going in the next 5 years? We're in the 2020s. If you read my post referencing NY State's DOT, you know there are 1,126 highway bridges in NYC that are over 53 years old (76.44% of the total). In the 2000s, 77 were built. In the 2010s, 83 were built. From 2020 to 2022, 23 were built. Many new structures are replacement bridges.

A little math will do. If we build at the same rate since 2020, we'll build 77 bridges in the 2020s. This is in line with the number of bridges built in the 2000s and 2010s (more or less 80).

If we continue to build at the rate we've been building in this millennium and replace the highway bridges that are over 53 years old, we'll need 147 years to replace them all and we'd still have 347 bridges to replace which correspond to the 23.56% of bridges that were less than 53 years old when we started. At that point the first bridge we built to replace the 76.44% stock will be 147 years old.

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