Why we stopped building cut and cover | Hacker News Reader

Why we stopped building cut and cover

worksinprogress.co

190 pointsjseliger172 comments

Recently in the SF Bay Area, there's been a lot of displeasure by transit activists that object to VTA's BART to San Jose extension (it's being built by VTA not BART) who had the choice between two tunneling options:

1. Two small-bore TBMs ~2 stories underground, one for rail in each direction. This would require cut and cover for the stations only

2. One large-bore TBM ~7 stories underground, with technically enough space to fit an entire station platform inside but displaces a HUGE amount of soil/rock along the entire line, and require very deep stations that take a long time for riders to enter/exit.

VTA consultants went with option 2 because they didn't want to disrupt the surface (again, only for the few blocks where the stations would be built) even though it costs $$ billions more.

Many transit activists (including me) are upset because it makes the project both take much longer and cost more. We could save money by literally just giving billions of dollars to the businesses on the affected blocks. There's no geo-technical reason to go with the large-bore option. This has also led to a lot of recent VTA-negativity among these activists.

I have the same reaction. It seems to me that we could pay every business impacted by the work and come out ahead financially AND ahead on quality of service.

Seems like VTA has so much money to play with they can't be arsed to save a few million here and there. https://www.youtube.com/watch?v=_pGUE1drr7A

It's not that simple as "TBM is better" as others also have chimed in to say here.

Real life example underway now: there's an SFPUC project in SF Mission district to improve stormwater drainage. City proposes TBM but this will result in years of having a huge tunnel entrance work facility in a residential neighborhood. Cut and cover would affect specific blocks but only for months and then move on to the next. Which is better?

PS. To all the OpenAI folks, this project is happening around all your offices!

Another real life example of TBM happening now is the SkyTrain extension in Vancouver, Canada. It covers quite a distance and is rather impressive, all stations being built concurrently, with some main road sections needing to be suspended. No shortage of complaints, but there were also no shortage of complaints when they built a previous line with cut and cover. I don't think it would be remotely feasible otherwise.

To me this sounds like TBM to would still be better.

You’re pissing off one set of residents immensely rather than every resident in the area sequentially. The marginal harm you do to yourself by pissing off residents is diminishing. Better to piss off fewer voters.

> You’re pissing off one set of residents immensely rather than every resident in the area sequentially. The marginal harm you do to yourself by pissing off residents is diminishing. Better to piss off fewer voters.

This is the kind of thinking that leaves us mired in the past, unfortunately. As soon as these projects are completed everyone loves them and completely forgets about any minor transient misery a couple of restaurants were caused. Compensate them and move on. The billions of dollars saved using cut & cover vs. a TBM sets up a heck of a compensation fund.

There's this real unstated mindset now where nobody should ever be inconvenienced, ever, no matter how mildly. It really holds back urban development. People will get over it.

Robert Moses ran rough over New York for a decade or so and they are still paying the price for his roads. We have gone too far for sure, but there is a reason we did.

I have developed this feeling that the govt is so stingy with small amounts to compensate businesses yet are willing to waste great amounts in other cases. I guess that's politics for you.

From your comment I think you are viewing this as a cultural problem.

It’s an optimisation problem of our political system. It’s not that we are not wanting to inconvenience people. It’s that people have rights relating to property and our electoral system is set up geographically so benefits that are non-local are externalised in electoral calculus.

Political systems are complex adaptive systems. They exist to perpetuate themselves. Their decisions will be whatever leads to their short term (read the foreseeable future of the humans involved) survival.

This isn’t an indictment of democracy itself but our system could need to be renovated. It is a little pathologically short circuited.

I very much agree with this broadly.

> It’s that people have rights relating to property and our electoral system is set up geographically so benefits that are non-local are externalised in electoral calculus.

For what it's worth, people don't really have the property rights they think they do. Eminent domain was brought in for exactly this kind of purpose decades and decades ago, and used extensively. We've just decided to stop using it.

Interestingly, the existence of TBMs has made SF Bay Area transit impossible to construct. Because TBMs exist, cut-and-cover is impossible since it can be pointed to as an alternative mechanism. However, they are hopelessly expensive here and consequently nothing gets built. Fascinating outcome.

I think that's a cool outcome in a coordination problem, where added technology makes neither technology workable.

This article was wicked sick, by the way. Great use of illustrations etc. This is free? Incredible. It's like the old web.

The tunnel itself (regardless of method) isn't the expensive part. Dense urban environments have a ton of stuff underground that was never accurately mapped. People don't like a city block bursting into flames because you hit a 4" gas line or the building they are in collapsing because it has an unmarked piling.

Building up is actually a cheaper solution, we just need to get the NIMBYs under control. Imagine how nice it would be with 101 and 280 being double deckers the whole way.

Fortunately, younger cities like London and Paris don't have the problem that ancient metropolises like San Francisco have, so they can build subway at a fraction of the cost of $4b/mi that SF needs to ensure that it's built right. There's a lot of history in California. Pretty unique in that regard.

To be honest, I like 280 without there being something on top of it, but if that's what's necessary to get a rail line down there I'd gladly accept it. Just the per-mile cost. Well, I'm not looking forward to paying more than half of every marginal dollar to the government so it can give it to its cronies who just happen to be husbands of famous California politicians.

I’m not sure they were at all implying that California was exceptional in that regard, to be fair, but at least that urban tunneling involves many costs besides the physical boring.

In any case, I wouldn’t use the UK as an example of tunneling efficiently. Crossrail, for instance, is on the order of more expensive urban US projects and there’s a fairly consistent recent history of either not building or letting existing rail infrastructure decay.

This link provides a decently contextualized comparison IMO, although it is slightly out of date now: https://pedestrianobservations.com/2011/05/16/us-rail-constr...

The funny thing is that Crossrail, the most humongously expensive UK rail project, is somehow a third the cost per mile as what SF quotes for its newest subway.

Even better than expanding 101 and 280 would be to vastly improve the public transit down the peninsula. There is no reason going from my apartment in SF to San Mateo should take over 90 minutes via public transit. There should be constant rapid busses through SF to every Caltrain stop in the city. Hopefully Caltrains electrification + timing improvements make this all more feasible.

The fact that it’s one of the most technical areas in the world and we’re stuck driving between SF and the valley is a disgrace

The fact is that San Mateo was built as a suburb of San Francisco, and the transit choices were built as a function of residents commuting into San Francisco.

Why did you choose to live in San Francisco? You cannot expect the transit system to revolve on a dime around your housing & employment choices.

This is such a weird comment. If transit systems arent built around people's housing and employment, its useless. San Francisco is a huge city, with a significant population that commutes south as well. Even if the transit was originally made for people commuting into SF, it clearly isnt what is needed the most now. Downtown SF office space has significant vacancies, and I would guess there is a similar number of workers commuting south as there are commuting north.

Caltrain's current ridership (very poor) demonstrates the need to change the connecting systems so it is popular again. The idea of having rapid busses connecting to the caltrain stops (especially 22nd and bayshore stations) is hardly a massive thing, and could significantly improve transit across the Bay.

Building robust transit between SF and San Mateo is good for everyone, its not selfishness.

> San Francisco is a huge city

It's got under a million people, and is only the second largest in the Bay Area. It's locally very important, but let's not get carried away here.

Why is it Caltrain’s fault that you chose to live far from a station, your employer chose to lease offices far from a station, and you chose to work for said employer?

I didnt say its Caltrains fault anywhere, I simply gave suggestions on how they can make public transit down the Bay significantly better, which should be their overall goal. Its also very relevant since their ridership is only <40% of pre-pandemic levels. I dont really understand why you are so against improving public transit access in a corridor that could really benefit. The whole area is a relatively plot of land, it is almost perfect for public transit

For that matter, why Caltrain? it should all be Bart.

The name should not matter. There are sometimes good reasons to have more than one operator in a metro area for various reasons. However there needs to be one fare/transfer system across the entire metro with a price cap.

You can have various systems of zones or service levels, but there needs to be a maximum cost it is not possible to exceed to make it easy to budget. People who expect to hit that maximum will not hesitate to use transit or send their kids on it and thus are more likely to decide they don't need the car (even though a car probably costs more most people don't account for the costs of a trip)

They are piloting fares carrying over between transit rides, which could be a great solution for the people who think it’s too expensive. In general, taking public transit is already cheaper than driving, but it would be really really good if we could market that better. Some people think east bay -> SF for 5.50 each way is too expensive, when the bridge toll alone is almost the same price.

Bart would be great, but Caltrain is already there, and is electrified now. I definitely support bringing it all under one roof, but for now I just think it’s important to actually get Caltrain on a functional schedule.

In the future, I’d love if Bart could build an extension past millbrae, but they have some other more important things to do imo

It will be down to policy not actual lack of data on infrastructure. Or is the expensive part the mapping? Or maybe the insurance?

Older bigger cities have built huge underground infrastructure recently. Londons power tunnels & crossrail for example.

It will be down to policy not actual lack of data on infrastructure.

It's absolutely about the lack of data about historical infrastructure. LA's Regional Connector line was delayed for years, and the budget ballooned by over a billion dollars, due to the discovery of thousands of undocumented utility lines (still in use) along the route. This necessitated dramatic changes to the project timeline and scope, since the construction authority had to reroute all of those utility lines.

Places in Italy where there is a lot worse stuff underground - like priceless archeological artifacts many to tunnel a lot cheaper than the US where there isn't such things (in the US there wasn't many materials available that would last in the natives trash piles - if there was there would be interest)

Here I was thinking you were talking about elevated rail and putting trains back on the lower deck of the bay bridge... but no, you're talking about freeway expansion in the core Bay Area? Not gonna happen.

> Not gonna happen.

I've never heard anyone successfully articulate why building enough roads to meet demand is such a bad idea. People need to get around and Caltrans has demonstrated they are far more competent and capable than BART or MUNI.

Let's not forget 1989 Loma Prieta quake that caused the top deck of the bay bridge to collapse. https://en.wikipedia.org/wiki/1989_Loma_Prieta_earthquake

Which was actually a lot less dramatic than how people seem to remember it. A 70 foot section disconnected at one end. https://en.m.wikipedia.org/wiki/File:Bay_Bridge_collapse.jpg

Freeway construction has changed a lot since the 70s and 80s. We now use ductile concrete that can flex without breaking, do extensive soil analysis for footings, and add seismic isolation systems in high risk areas.

Perhaps, but the Nimitz Freeway probably makes a better example for what the commenter you were responding to was getting at:

"The highest number of deaths, 42, occurred in Oakland because of the collapse of the Cypress Street Viaduct on the Nimitz Freeway (Interstate 880), where the upper level of a double-deck portion of the freeway collapsed, crushing the cars on the lower level, and causing crashes on the upper level." (https://web.archive.org/web/20090707140922im_/http://home.pa...)

Fascinating post! I had no idea about this transition from cut-and-cover to TBMs. It's always interesting to see how approaches change as technology advances and the ratio of cost to benefit changes.

The author paints with too broad a brush. There is significant differences in markets that drive these decisions. Cut-and-cover is standard in my state, but the land cost, density, and regulatory environment allow this. Directional drilling and jack-and-bore is very common for small diameter excavation, though.

> the land cost, density, and regulatory environment

Cheap land, low density, lax environmental regulation?

Correct. A major cut and cover in downtown Dallas would be insane. Bringing a TBM to put in a tunnel for bikes in Springdale Arkansas would be insane.

If you're ever in Sydney, go to the St. James station (I think) and you'll see lots of historical photos of using horse and carriage to build the first Sydney metro stations. Very very cool!

I hear there's a museum in Tokyo as well. When I was there in the 90's they were excavating a station that was found by a construction crew. The plan was to turn it into a subway history museum. I was told that the line was abandoned after an earthquake, and they lost track of the location of some of the stations (or at least, this one).

It was on a green strip of undeveloped land, so I have a small suspicion that a landslide may have been involved. I mean how else do you 'lose' a building?

It is highly doubtful that anyone in bubble-era Japan “lost” a piece of property. The rail companies in particular are keen, savvy property developers.

During the bubble, the Imperial Palace grounds had a higher real estate valuation than all of California.

I feel like you might be underestimating the age of subway lines.

2027 will be the centennial anniversary of the Ginza Line, and that's a baby compared to Paddington Station, which had its sesquicentennial a decade ago.

Apparently the Tokyo postal service had a private line in 1915. I kinda wonder if that's the one they 'found'.

Depending on how dense the urban area the cost of moving utilities even before construction is astronomical. If it can be done to coincide with cut and cover it can still be financial effective.

It is highly disruptive to the entire area so it really depends on where the tunnel is being placed. Appropriate traffic and pedestrian accommodation plans are essential.

I'm very grateful for those posting and upvoting interesting construction articles on HN, this is a key area of our economy that is stagnant and could really use some improvement. Traditional media do a terrible job of coverage, and spreading articles like this helps get better mainstream coverage.

A lot of the bad things about construction come down to incumbent players being able to force extremely costly methods on anybody who wants to improve the world. So a lot of the challenge is political. Solving political problems is really hard, but when technology can sidestep the problem, there's a lot that becomes possible.

For those in the Bay Area, we are seeing aversion to cut and cover be a huge hassle for our stations. The depth of some of the new transit stations will be a huge inconvenience for generations of transit users, all to satisfy a short term disruption of a far smaller number of people. This problem could have been solved with money, for those affected, if it were not for the politics.

Deep stations are also unbelievably expensive. Deep tunnels are not that bad, but the resulting stations explode the budget for transit to the point getting the project green lit in the first place is nearly impossible. Plus with the same set of dollars you are building a lot less transit.

Deep stations also add a bunch of hassle for the users. It just takes longer to get down 5 stories underground.

Exactly. When I get to a cut and cover station, it's often just a single flight of stairs down. It's often only 15 seconds or so to reach the track and wait for the train.

Stations along bored tunnels sometimes take as much as 5 minutes to go from street to train. One I used to regularly use had three separate multi-story escalators, in addition to long walkways between them.

So even if cut and cover disrupts businesses and car traffic, I can't help but wonder if decades of extra delays to reach the tracks from many thousands of people a day doesn't wind up outweighing that.

Is there a reason bored tunnels need to be substantially deeper? Does boring lead to structural stability issues that the installation of the tunnel structure doesn't mitigate?

I do know that tunnel boring machines can disturb the surface, and that substantial effort goes into minimizing this. (That is, minimal surface disturbance isn't automatic on account of the fact that you're boring.) I believe it sometimes has to do with how much pressure they need to apply to the tunnel face; the ideal pressure for cutting can lead to sink or swell on the surface. Presumably this is less of an issue the deeper you go. I don't know much about this stuff though. This is maybe relevant:

> This thesis summarizes and evaluates the performance of Tunnel Boring Machine (TBM) construction in Singapore's MRT network. Surface settlement induced by the tunneling process can cause damage to underground utilities and foundations and buildings and/or disrupt daily life by damaging roads and pavements, and is used in this thesis as a measure of performance.

https://dspace.mit.edu/handle/1721.1/82809

So I did a little research on this, and it seems to be two main things.

Partly yes it seems to be a question of stability -- you're not going to bore and leave just a couple of feet of soil above, because of the way you want the arch of the tunnel to support itself, and that's not going to be strong enough. And close to the surface you've got looser soil etc. Going deeper does provide greater stability, in a way that isn't needed for cut-and-cover because that is supported by steel beams, not arches. But this doesn't generally require you to go crazy deep.

The bigger factor behind these crazy-deep tunnels seems to be pre-existing infrastructure. If you're doing cut-and-cover, you're digging out all of the infrastructure first and then replacing it -- it's highly disruptive. While if you're boring a tunnel, you need to go below everything that already exists -- sewers, water lines, deep building foundations, pre-existing subway lines that it crosses underneath, etc.

> The bigger factor behind these crazy-deep tunnels seems to be pre-existing infrastructure. If you're doing cut-and-cover, you're digging out all of the infrastructure first and then replacing it -- it's highly disruptive. While if you're boring a tunnel, you need to go below everything that already exists -- sewers, water lines, deep building foundations, pre-existing subway lines that it crosses underneath, etc.

Makes perfect sense!

And yeah, it's yet another case of path dependence: we'd build far different cities if we had the option of designing "from scratch" rather than layering retrofit over retrofit under retrofit.

In an ideal world, we'd have tunnels connecting B1/B2 of every major building in a city, and many people's trips would be elevator-transit-elevator.

It's absurd to talk about transit times to destinations when just getting to track level and back can take longer than the trip

This is one of those things that people overlook. Travel times should be "door to door" or some similar comparison; sure it makes cars look a bit better but it can make things like trains and walking look even better. A two hour flight might be bounded by 1+ hours on either end (including security, etc), whereas a two hour train ride might literally be two hours + five minutes walk on each end.

You need to factor in the fact that adjoining landowners are often rich campaign contributors, whereas the patrons of public transit are often the poors or the invisible help.

As is often the case, the answer is "follow the money".

The deepest station in Seattle has smelled like someone tried to make cheese from moldy gym socks since the day it opened.

I believe it opened and immediately shut again so they could try to deal with the water problem [though responder says no]. I went through when it was briefly open and again after. They made it less bad, but it was still pretty awful.

A club I belonged to met at a library near the station so it was easiest for me to just hop on the light rail after work and then take it back to the bus terminal after but gods did I want to hold my breath the entire time.

> The deepest station in Seattle has smelled like someone tried to make cheese from moldy gym socks since the day it opened.

Maybe it's just a matter of opinion, but I never found the Beacon Hill light rail station to smell like anything other than raw concrete, similar to DC metro or any other deep tunnel system.

I lived in the neighborhood at the time, and don't remember the station shutting down due to water ingress. Opening was delayed due to issues with overexcavation, but that threat was with sinkholes opening to the public above, not issues with the tunnel itself.

My nose is pretty good at picking up mildew smells. I've been in plenty of rooms where half the people can't smell anything.

After years of rhinitis my sense of smell is half-shot, but I can still walk into a room and find the forgotten towel moldering away under a chair or table. Why couldn't I have lost that power and kept something more pleasant?

Could be of note that Stockholm is building the world's second-deepest subway station right now[1]. Though there's no real alternative to that because it needs to go under water (well, in the ground under water) towards the next station.

[1]: https://www.youtube.com/watch?v=TEYvywnJy78 (Swedish)

When there isn't really a choice, fine build a deep station. Montreal is building a station 72m down, but it's driven by surrounding geography. What's a bad decision is deep tunnelling just because, like Toronto on the York subway extension. Deep bore under suburbia is really wasteful spending and that same transit budget could be building a lot more transit.

https://en.wikipedia.org/wiki/Édouard-Montpetit_station#REM_...

I lost 25 lbs in 6 months running down and walking up the looooong escalators in Stockholm because it took way, way too long to stand and ride.

Why are deep stations expensive but tunnels cheap? I'd guess the opposite, tunnels being larger.

In an urban subway line, stations may cover ~25% of the line. The platforms are long, while the distances between stations are often short. And while tunnels are standardized and their construction is largely automated, each station is a unique project that needs to be adapted to the specific location.

Because you need to dig out all that dirt, and this is normally done cut and cover. Even if you are only digging for stairs and elevators (building the station in the tunnel as Madrid does) that is a long way down. For shallow stations you can tell most people to walk down the stairs, but for deep stations nobody will so you have to build enough expensive elevators to handle everyone (and you still need the stairs for fire escape). Deep stations also mean people will be on the elevator longer so you need even more of them. (people may be running late so they need to load fast and it better not be long for the elevator to come when someone needs to get someplace)

> elevators

How are the elevators any more of a problem than in buildings, where they are commonplace, often for much taller structures (i.e., many more floors), and not considered a major expense?

Edit: Thanks, good points about the volume/throughput.

A subway station needs to be able to handle, during rush hour, bursts of 100 people arriving every 2-3 minutes. A building generally does not.

This is why even deep subway stations usually go with multiple levels of escalators to keep the flow of people moving continuously.

Metro stations have enormous throughput in comparison to a building.

Escalators usually carry more people if they are offered at least. Elevators get disgusting fast.

In the SF Bay Area, BART closed the station restrooms and so now homeless people and drunks use the elevators and escalators as toilets

https://www.sfgate.com/bayarea/article/Rights-group-sues-BAR...

For deep stations they don't work as well - you end up with a lot of switch backs.

Depends but you can have very long ones, too. In koreatown LA runs one of the longest escalators in the world down into the depths. Even the escalators at Universal Studios Hollywood have only a few landings and get you down an entire mountainside of vertical drop. I’d still take a switchback over cramming into what is basically a dumpster and urinal.

Here's my startup thesis for this space, free for anyone who wants it

1. Most delays in tunneling projects are due to elongated decision making processes 2. The majority of the cost of the machines are their initial construction, not operation or maintenance

Solution: fleet of TBMS are set off in arbitrary directions that bounce off the city borders like the screen saver with the bouncing ball. This creates a large network of tunnels all across the city. When it comes time to decide to put new infrastructure in, one of these tunnels is already there somewhere close, just have to dig down to it. 0 decision fatigue/cost, max efficiency for cost per tunnel foot.

How could this problem be ‘solved with money, if it were not for the politics’ ?

Directly paying everyone living/working nearby to get them to accept cut and cover construction? Wouldn’t that cost even more then building it deep underground, after all the legal fees and court challenges, once it’s said and done?

It would depend on the implementation. Cut and cover could be done in blocks rather than shutting down long corridors at a time, combined with legislation setting clear limits on affected compensation and their standing to sue over small delays. That could easily pencil out to much cheaper than deep bored tunnels and stations.

Legislation that restricts local resident’s standing to sue? Can you provide some examples where that has ever been implemented in the US, in any scenario, or even judicial opinions to that effect?

NYC is paying $4B/mile for their latest tunneling projects. That works out to $200M/block.

Lot of money to go around, I'd argue its more political will than cost.

Don't forget theres years of legal fees & court challenges even with deep tunneling!

Alon Levy's Transit Construction Costs project breaks down where NYC's (extremely) high costs go - https://pedestrianobservations.com/2023/02/06/our-constructi...

There's no simple reason - basically everything that can cost more, does.

NYT had some great articles too.

A lot of it is that every last bit of expertise is outsourced.. not just physical labor and renting equipment but even the project planning, management and oversight. You'd think given decades of capital programs lined up, the state would want to have their own planning/management/oversight staff so that interests are more aligned.

You can't pay yet another vendor to care about & enforce cost discipline upon all the other vendors you are paying..

You also can't discount antiquated union work rules & strong lobbying. NYC transit work sites are more heavily overstaffed compared even to the equivalent Paris transit project. "Our unions have more power than in France" is a pretty high bar. From having 3x the staffing on the Tunnel Boring Machine to minimum required union machine oilers on-site based on the level of hand oiling that 1970s equipment needed (far more).

It's like if IT's staffing / roles were frozen in time from the 1970s and we still paid someone to sort punchcards.

> NYC is paying $4B/mile for their latest tunneling projects.

So only what, about 30x as much as Madrid spent?

Can be solved by doing an emergency nationalisation, i.e. pay first, everything else after, which leaves challenging the compensation to the after.

This problem couldn't, but a lot of others could. Grandparent comment spoke generally about all construction.

As far as I understand it, and this may be outdated, cut and cover is way cheaper than boring. And you only bored tunnels if you had no other choice --like Big Bertha in Seattle. BaRT was mostly cut and cover as obviated by going under Market and Mission streets.

Maybe new boring machines are faster and cheaper and break down less than before.

Yes, cut and cover is cheaper to execute than using a boring machine in most cases and when possible.

But the externalities of cut and cover can be very expensive (blocks streets, and hurts nearby businessen even to the point of going out of business). Those second order effects, even if transient on a long term scale, can cause expensive hold ups. Other externalities are the need to get around existing infrastructure, some of which could have over a century of continuous use.

So for example in NY it is almost impossible (look at the 2nd ave subway, which is mostly pretty shallow) while in LA cut and cover was no problem at all.

I wonder if the price difference between boring and cut and cover is greater than the cost to just...cover business's expenses (rent, loan interest, payroll) for the time it takes to get cut and cover done on that block. Could we just pay them off?

That sounds like it could be cost effective if one only includes the individual businesses and cover their losses, but it can still cause second order effect harm, like customers changing habits and not returning to the original place. Something to think about. Suboptimal infrastructure is also costly, of course...

The justification for business owners making profits is that it's payment for taking risks. Why then are we trying to shield them from risks while still allowing them to make profits?

Business owners making profit needs no justification, that's entirely backward. Anywhere there are people, there are goods for sale. The ones who need to justify themselves are the ones who propose to restrict this. It can be done, I consider the restrictions on the nuclear weapons and slave markets eminently justifiable. But in a free society, the default is freedom.

Because we want business to take those risks. In the end I benefit from those businesses - not all of them, but some of them.

Businesses should take risks. However government should not add extra risk without careful consideration.

Honestly I'd be fine with it if the public agencies just used it as a justification for a eminent-domain style "We're going to do this project this way in the interest of the public, we're giving you some cash to cover your immediate costs, and that's that."

For private sector projects people do get bought off (in a non-corrupt sense of that phrase) but that seems to be unacceptable for public projects for some reason.

I'm talking about the US here -- no idea elsewhere.

I assume the second private was supposed to be public?

Yes, thanks. I was still in the edit window so I fixed it.

What people often forget about modern cut and cover is that it is only disruptive for a short period of the project because they can put a temporary road deck over the cut and do most disruptive work overnight. Its how LA metro built a subway station in the middle of Beverly Hills.

There are several options to make cut and cover less disruptive. Other options are dig in the sidewall supports, then build the cover over the current road surface, finally dig out underneath. It is still tunneling, but it uses most of what makes cut and cover cheaper than a TBM.

I wonder how many different ways people have tried cut and cover over the years. I'm talking here of the horizontal part of the project, not the vertical. It seems like you usually have one, or maybe two, moving work sites, and they go block by block removing the street, and replacing it behind them at some point. Any business near the sites is choked off from foot traffic for a while, even if the site isn't in front of their door yet.

Is it more or less disruptive if you do a checkerboard pattern instead? Instead of n months of construction around your favorite coffee shop, would it be better to have n/2 months of construction now, and n/2 months of construction in July? Maybe that depends on where you are on the street. If, for instance, you start at both ends, then the businesses in the middle of the cut have construction sites boxing them in for almost twice as long as anyone else does. Or maybe that just means more people of means mad at elected officials.

The problem is the street overall is blocked off for the duration. Sure it looks like only one block is stopped, but in reality people who have to travel that block are backed up all the way, and so they will look for alternate routes for the duration.

If you could build the entire thing in 2 weeks (per year) people would be happy with a full road closure - they would all take vacation for those two weeks. This is for the entire city - close all roads to non-emergency traffic for two weeks, fix them all up - everyone not involved in road work or essential services would just go on vacation. You cannot do this of course, but that is what people really want.

I thought about that too. The problem with trains is that they always need to run in the primary direction of traffic. So you can't really build them on cross-streets and avoid disrupting the main thoroughfares. Otherwise you'd often end up with a train to nowhere. The main exception being when traffic is curved, going around some obstruction that the train can cut across.

I recall when South Lake Union got its trolley, one of the things they pointed out was that property values next to a trolley drop, but property values 1 block away go up more. Everyone wants to be a couple blocks from transit, not living above it. So even if you avoided the main road going parallel to it, you're probably tearing up even more desirable real estate and commercial zoning.

> As far as I understand it, and this may be outdated cut and cover is way cheaper than boring.

When you ignore all the side effects, sure (especially if you also ignore the risks of blowing the timeline).

Trenchless tech is spreading fast even in small-ish (street utility scale) construction.

> Maybe new boring machines are faster and cheaper than they used to be.

I'm not sure that's even the case, AFAIK TBMs are still custom-built for the job, highly geology-dependent, and require a ton of babysitting. If you hit an unexpected patch of really different geology things can get really dicey.

> TBMs are still custom-built for the job

This is semi-true. They are built for the job, but the design is standard. What is custom is the exact size of the tunnel, and thus all the supports.

TBMs generally last a lot longer than the job, so a city could save a lot of money if they planed to keep using their TBM, constantly digging tunnels. Start with a north-south line, then use the same TBM to build an east-west line (or southeast/northwest), and so on. However most cities are unable to find the continuous budget to do that and so when they are ready for the next one the old TBM is no longer worth using, and in any case they no longer have trained crew to run it.

> highly geology-dependent,

Soft water logged earth needs different machines from hard rock. There are combination machines, but if you can determine which you need you save a lot of money ordering the geology specific machine. Get this wrong and you end up with a TBM and partial tunnel under the city.

> require a ton of babysitting.

12 people per shift is the number I've heard (NYC uses double which is one of the smaller reasons things cost so much there). The work is mostly routine though. However the TBMs do break once in a while and they everything stops while you repair them.

There's the construction cost, and there's lost income from the people who voted for you. Not all of the money spent on construction is tax dollars.

Think about every time you've been stuck in traffic because there are 3 roads that get you from A to B, and some jackass at city hall thought it would be a good idea to permit road work on 2 of them on the same day.

We are used to highway on-ramps being replaced in days to weeks, but removing an entire street, digging up everything under it, being careful not to nick the utility lines and pipes, then packing dirt back in around them without tearing them, then rebuilding the street on top, that's a lot. Especially for the businesses on that road.

We end up with transportation solutions that are suboptimal because we don't have the political will to tear off the bandaid. This on-ramp is in the wrong place because the old one was in the right place, but was built in a terrible way and had to be removed for safety while still handling daily commutes.

The article discusses this extensively.

Did you read? Article states that cut and cover is still much cheaper technically, but can end up being practically more expensive due to the political/legal ramifications of the surface disruption.

Depends, Gaoxiong did a C&C and they were able to mostly mitigate the second order effects of C&C. Yes, in some sections some traffic was affected more, but apparently it wasn't widely disruptive. It can be done.

It helps when you can complete the project in a few years and not take a decade to build out a single line. So politics does have an impact on feasibility and practicality of C&C.

There's a short cut & cover freight railway "tunnel" near me in Footscray, Victoria, Australia (just west of central Melbourne). Here's the Google street view: https://www.google.com/maps/@-37.8035409,144.9065655,3a,75y,...

I used to walk over it almost every day when I worked at a coworking space in the old Lonely Planet HQ building. I think a lot of locals drive over it without ever realizing it's there.

What's wrong with elevated trains?

They are very loud, they bathe streets/sidewalks/buildings in permanent shade, etc.

> They are very loud

Loud and sometimes vibration-inducing. But this seems potentially feasible to mitigate through sound insulation (both on the train and on the buildings; frankly, our buildings should have a lot more sound isolation than they do).

https://news.ycombinator.com/item?id=39401709 mentions newer elevated trains generating less noise, by designing for that requirement.

> they bathe streets/sidewalks/buildings in permanent shade

And permanent rain-cover. Seems like it'd often be a feature for many, though a bug for others.

I live next to a bridge in NYC that carries trains, so I have experience here.

The set back from the bridge to my building is about 5-10x as far from my window as an elevated train line running on an avenue would be.

I have new windows, plus a second set of quiet windows installed within the windows. Essentially quadruple pane windows. It makes them unusable for ventilation. Plus I have sound deadening curtains, sound dampeners on walls, etc.

Believe me, it is loud. There is no mitigation you can do to make it not noticeable. You can only make it tolerable. The cost to get it to that level is not insignificant.

In an ideal world, housing wouldn't be built immediately on major transit lines, but a (walkable) short distance away. Alas, city planners seem dead-set that new construction must _only_ happen within a block of major roads or train lines. There seems to be a lot of urban malpractice that prevents us from making good choices.

In an ideal world, housing is built directly above transit stations, so people can get on the train without even having to go outdoors, leaving it the most obvious choice for almost all journeys.

Look at what they've achieved with this in Hong Kong. Plus the lines and stations basically pay for themselves due to revenues from residential property.

it seems to me elevated trains are a lot quieter running on concrete structures than on steel, as in NYC and Chicago.

It's not apples to apples (light rail + heavy), but from experience the elevated parts of LA's Expo Line are a lot quieter than the Chicago L.

There is mitigation that can be done for the noise. However it isn't something you can do - the city would have to rebuild the tracks to modern standards.

The rain cover is really outweighed by shade/lack of sunlight. The shade tends to make the street level experience more gloomy and a significantly worse experience that people tend to avoid.

Maybe with climate change and more brutal summers that calculus will change.

Hotter weather may change some of that but street level tends to be dark and not pleasant to be in. Like it or not, people tend to associate those areas with higher crime and the shops at street level tend to get noticeable less traffic. It depends on the size of the tracks but if you've been to the loop in Chicago or in places in NYC with elevated trains, the difference in the streets with elevated tracks and the streets without are noticeable.

And there's something to be said for giving residents and visitors spectacular views of the city.

Interestingly, for the suburbs here in Melbourne they offered two options for grade separation:

1. Elevated rail

2. Trenches with no cover

A series of campaigners in areas with higher property values wanted the trenches for “privacy” reasons and in the end many of them got them but the elevated rail receiving citizens got bike paths, basketball courts, car parks, improved walkability, generally more public space.

Having experienced the two, the elevated rail is far better.

The totally new line they are building though will be a TBM.

I recall from a PBS special that in the late 1800s, NYC suffered a blizzard that shut down even elevated trains for days. Hence, the move towards building underground.

They also got rid of surface running cars because of the same reason.

They still make a lot of noise.

Newer ones make less noise. The old steel structures in Chicago make a lot of noise. The sky train in Vancouver isn't silent, but it is not loud: they knew noise could be an issue and so built to make it not a problem.

I for one, would much rather live in Elwood Blues's room than next to ANY interstate.

> We used to dig up roads to put trains underneath – cheaply. Ever-better tunnel boring machines have made the disruption this causes unnecessary.

What? Sure, tunneling machines make less disruption but unnecessary? You still have to build the stations, entrances, and venting systems. All of those breach the surface and the space needed to facilitate the construction still causes lots of disruption.

But yes, more public transportation please. Lots of it!

They didn't say disruption free. The quantity of disruption reduced is the part which is no longer necessary.

Hear me out: tunnels for cyclists. If tunnels are cheap, and I'm guessing small tunnels are cheaper than big tunnels, then we should have tunnels for cyclists - maybe even right under the sidewalks.

I'm a big fan of turning some existing roads into cyclist and local access only roads, and then discouraging extended biking on other roads. Tunnels could certainly be part of that. In general, I don't think it's ever going to be safe for bikes and cars to share the same roadway any more than it would be for cars and pedestrians to travel on the same surfaces. For short distances, sure, but not on big arterial routes where everybody is at war with everyone else all the time.

One great benefit of cycling is exercising in the fresh air, seeing the world, and connecting with the people around you.

> connecting with the people around you.

For the 0.5 seconds you're next to them before you pass them or they pass you?

That is plenty of time to smile, say hello, say excuse me, have a face-to-face interaction. You wave at the child staring at you, you make appropriate warm sounds toward the dog barking with its tail wagging. You all react together to the funny sight, to the ambulance, to the sun in your eyes.

You also connect by just seeing what people are doing; you are out there with them. You have time and visibility to see the whole world, 360 deg x 180 deg.

Also you stop, maybe at a light, maybe to look at something, and see and talk to people there. You work out a traffic issue by talking and smiling, face to face, not by honking and banging on your dashboard. You see friends and say hello. You see somebody do something nice and say 'thank you'.

You have an extremely romanticized idea of human interaction.

It's not romanticized, I do it every day. Not everyone responds but that's fine; it still has an effect, and many do respond.

People assume it's not possible, that others are paranoid or bad-willed, and so treat others accordingly or at least don't try. Just try; it works fine. You need to read people and respect them - just basic primate social skill: obviously, some people are busy, upset, etc. and don't want to be bothered. But just trust people are good-willed and friendly, treat them accordingly, and you'll get plenty of good responses. It depends on your mood too; it comes through; if you are angry and trying to be happy, people can sense it - we all have years of experience reading others.

Even crazier is that people will actually argue against it, insisting it can't be true, objecting to anyone doing it or trying it. You have to wonder what that's about; that, I think, is very revealing about our society and some of its social trends.

why though? building good cycling infrastructure at grade just isn't that difficult, other than finding the political will to make it happen. it doesn't take up a lot of space, it's cheap, and when it's at grade it provides easy access for cyclists to stop at all the shops or other destinations along their route.

the biggest impediment to cycling infrastructure is a social perception that cycling is elitist, and that spending money on it is a waste. if we can't even fund an 3m wide strip of asphalt or a couple of jersey walls to protect a bike lane, how are you going to find the money for tunnels?

While I support the infrastructure, I don't entirely agree with the analysis:

On city roads, a lane is very valuable real estate. As a simple example, taking a lane out of a busy NYC street can have a big effect on car traffic.

> the biggest impediment to cycling infrastructure is a social perception that cycling is elitist, and that spending money on it is a waste.

IME it is elitist, unfortunately. I see mostly delivery people and 'elites' cycling in the city, and the cycling clubs advocate for a lot of infrastructure but they don't make much effort to bring people into cycling. The infastructure is highly underutilized - it looks like those cycling clubs insisted on building that infrastructure just for their small membership.

It's a real risk to the infrastructure: Eventually other people are going to notice and say, 'why are we bothering with it' and 'let's use the mostly unused space for this other project'.

So valuable we let people park on it for free. As for utilization it's far more space efficient: we have a path in my town that handles a few thousand people while a street that did the same would be unpleasantly busy.

> So valuable we let people park on it for free.

Most cities have a large infrastructure to manage availability of parking, including laws, signs, meters, and meter enforcement. And in many of them, parking space utilization is very high.

It is still a tradeoff. It could be utilized for people doing their business in the city, instead an empty car takes prime real estate.

Utilization is high because it's such an inefficient way to transit people that in most cities it's always at capacity.

If cycling were safer and a more realistic option in regards to city layout, every walk of life would be cycling. It's a chicken and egg problem, lack of infra means cycling sucks for normal people, so no cyclists except roadies. No cyclists means no push for infra, no advocates.

I'm sure that's true in some places, but my original point (somewhere upthread) was that I've been in cities with plenty of cycling infra but where utilization was very low and mostly two walks of life, wealthy white people and delivery people.

So the a first step has been taken there, building the infrastructure. But they need to actively take the second step and spread cycling. 'Build it and they will come' doesn't seem to work.

At grade is awful, stopping everywhere. That includes in Amsterdam.

Benefits of tunnels would be

* No need to stop

* Protection from elements (I for one would be far happier riding in summer if it wasn't sweltering, or in winter if it wasn't bitterly cold and rain)

* Mostly flat tunnels (No hills to climb up and over)

* Certainty that the route won't be removed for some reason

Of course would never find the money.

Eyes on the street.

I'd argue the biggest impediment to good cycling infrastructure is the low utilization of the existing cycling infrastructure. I had a friend who insisted that most people want to cycle to work, but they are lacking the infrastructure. If we only build more bike lanes and bike paths, more people would choose to cycle instead of drive. The thing is, my city has an extensive set of bike paths. They're really nice and are a viable way to get places. They're also rarely used except for exercise or leisurely strolls.

Given most bike paths in my city are empty most of the time, why would we spend money on more cycling infrastructure? The low utilization - not a social perception - are why spending more money would be a waste.

Are you sure they are empty most of the time - bikes are small and so you may not notice them even though that paths are well used.

Are you sure those paths are viable to get places? In my city they appear that way if you don't ride them, but then you discover they can't get places because there is no useful connections. They have have a fence between them and stores. Or they only go through residential neighborhoods. Where I live they are setup to drive your bike to the trail head and go for a long exercise ride.

And then we blow wind down the tunnels, one in each direction, so they get a speed boost!

Real cyclists know if there’s any wind at all, it’s never tailwind.

Yeah I felt that one. But it actually makes sense. Due to the apparent wind (adding the vectors of wind and bike velocities together), and drag being proportional to the square of velocity, you will seldom feel a tailwind and headwinds will be amplified. And this spread widens the faster you ride, even turning lighter tailwinds into a headwind.

This is pretty common in Denver. There are lots of pedestrian/bicycle-only tunnels under many main roads just in my area. They recently spent a few million dollars improving an intersection nearby, and in the process added another cyclist tunnel underneath. It makes me really happy to see the city prioritize cyclists.

The tunnels are ways to cross the road - rather than a stoplight and crosswalk - or they follow the road and are essentially the bike lane?

Yep, usually underneath a freeway, railroad, or major roadway

https://cloudfront.traillink.com/photos/big-dry-creek-trail-...

You can bike along Big Dry Creek Trail for about 10-15 miles without ever having to interact with car traffic. And it runs right across a major suburb of Denver. I actually use it almost every day to commute for errands

My guess would be underpasses like along the Cherry Creek trail, but I wouldn't call those tunnels. It's also not very usable when it floods. Skip to 8:50 https://www.youtube.com/watch?v=M2z76dDcT8c

Up in Westminster/Broomfield, there are several actual bike tunnels that go underneath a main road e.g. on Big Dry Creek bike trail underneath Wadsworth Blvd.

The tunnels do get a bit wet/impassable if it has rained or snowed heavily, or if the nearby creek is running heavily (which is rare). But people dont typically bike in downpours.

It doesn’t really matter, the point is that cyclists are totally separated from car traffic.

I'll do you one better. You could contour the floor of the tunnel, texture the walls properly, and add some fans and create a quasi-hyperloop for cyclists.

Hear me out: elevated, enclosed cycleways with transparent walls and ceilings.

- Much cheaper to build than underground tunnels.

- Cyclists get a great view of the surroundings.

- Can be horizontal regardless of terrain, so that cycling is effortless.

- Can be climate-controlled, so people can bike all year round in any weather.

- Don't cause noise problems like trains or cars.

- And of course make cyclists 100% safe from cars.

I just thought of this idea and it's so amazing that I'm not sure why it's not everywhere.

> Hear me out: elevated, enclosed cycleways with transparent walls and ceilings.

Costs a fortune for window washers and graffiti removal.

They would also end up being used by squatters and for dumping trash.

Indeed, with how bad the housing crisis is in America, plenty of cities are having problems building any sort of public structure that has a roof on it...

Yeah, housing is definitely a bigger problem. I was thinking about it for some time, it seems the root of the problem is that rich homeowners try to prop up the value of their homes, by lobbying to stop new housing construction nearby. Basically cities want to grow, but existing homes act as a brake.

If that theory is true, maybe one possible solution is to pay rich folks to get out of the way. The city can offer to buy their land, tear down their home, build an apartment building in its place, and pay them a cut of all future rental income from that building. This way they won't feel like selling now is missing out on future increases in land value. They can use the income to live comfortably somewhere else, and the city becomes free to build up.

Cycling in tunnels would be incredibly depressing if it's long stretches of a route.

I'll bike in a tunnel all day long before risking it on public roads anywhere in America. At least for any kind of commute.

I'm on my bike to get someplace, not to enjoy the ride. I know my route to work. I know the alternates as well where they exist. There is no longer anything new to see so I'm not looking (except to watch for cars of course)

I'm also on my bike almost daily to get someplace, doesn't mean I don't enjoy the added benefit of scenery change, trees, being able to take a detour if I'm bored out of my mind of the same route, etc. Crossing the bridges in Stockholm always give me a lot of joy overlooking the water, seeing the city.

Being underground for most of my commute would be utterly depressing, I enjoy biking to see the world, not to just teleport to a place.

The problem with segregating transportation is you then have different levels of access.

If I bike on the street, I can stop at any location that addresses the street, same as any other street user. If I bike in the tunnel, there's not likely a ramp up for every business.

It gets worse when you don't have a bike tunnel on every street, because then I need to go out of my way to get to destinations off the tunnel street. And all the street users will yell at me to get back in my tunnel.

I don't see tunnels as a way to ban cyclists from the street. I think of it as a safer alternative for the cyclist. Dryer too and less windy. As much as I'd like for drivers to be alert, they just aren't.

Yeah, I'm no city or urban planner - I can't solve every problem. It was a thought and I think there's some merit to it.

Dang and others, would it make sense to change the HN posting workflow such that a one-paragraph ChatGPT-produced summary was the first visible comment? Or otherwise make a summary easy to find. Also, ask the poster if the title could be improved, and suggest a possibly better one? Maybe it'd be unwise, of course.

I think automated summaries encourage shallow engagement and poor(er) comment quality.

A summary is not the article, and the map is not the territory.

What do you think they would add, and why do you think that is a good thing?

The decision makers over HN as a software platform are pretty resistant to any sort of change, which is likely a mixture of deliberate intention but also lack of incentive to mess with what's already working.

What I want is something that says does the article actually say anything interesting beyond the headline. all too often I've clicked on a link and discovered the headline said it all - good for the headline, but bad for in-depth understanding - often the commenters know far more than the article.

In this case the article is worth reading. However it also is ignoring some important factors and so we still need to read the comments.

I think we should find ways to get ahead of the disruption that construction creates.

I know people and cities do not at all work in the way that I am about to describe, but imagine being able to shift the population of a city and all its necessary infrastructure to a second backup city so as to minimize disruptions.

All the necessary modifications could be made to the first city without affecting people living there because they would be living and working elsewhere until the work was complete.

Once the work is complete, everyone would go back to whatever address they previously had in the first city, and then work could start on improving the now vacant second city.

Obviously, there are lots of issues that I have not described like how this works when many places already have a housing shortage, and having to build that second city in an “empty” area that can be provisioned with the same quantity and quality of resources enjoyed by people of the first city.

In addition, I think a large complicating factor in construction today is something that I have not seen people talk about: when is it a good time to tear down existing structures. The lack of a “best before”/“expiration date” means structures stay up until failure or until the current owner wants to build something new in its place. The building stays up with possible inefficiencies (heating, cooling, energy use) that might be too expensive to remedy because of the age of structure.

Its amazing disruption is even relevant to the discussion at all. Cities should not be so brittle that having two lanes on a single road go down for a cut would make a dent. In reality they aren't, but people are emotional beasts, they don't want to have to detour their longstanding commute for reasons they don't see themselves benefiting from. So they dig in, and decide this couple block stretch of road surface is the hill I die on, and local politicians better be damn sure to listen because no one else votes in local elections but these emotionally driven pissed off people. The whole time the press is pandering to them with false equivalency two sides reporting, when really the story is often about suburban car driving wealthy people being mildly inconvenienced for maybe 20 months so that the working class can see a generational improvement in mobility, and this is somehow an unacceptable tradeoff to make because of the status of these people.

> Cities should not be so brittle that having two lanes on a single road go down for a cut would make a dent.

Unfortunately, as far as I can tell the way democracies fund major construction projects is to first wait until the existing infrastructure becomes completely unbearably overloaded, and only then to kick off a process that will solve the problem in 10 years time.

According to the example in the article, the damage from cut and cover also displaces the sidewalks (so that customers of a business have to reach the business via alleys) and causes evacuations and flooding.

In the Roncesvalles neighbourhood of Toronto (not as dense as downtown, but still an extremely walkable and bikeable commercial district), they had a major section of street closed for surface rail replacement for a significant amount of time, and it was very hard on businesses in that stretch -- people just didn't go there because it was noisy and dirty and unpredictably hard to get to and from places.

I don't think the objection in built-up areas is (just?) about driving.

You seem to think road lanes are cheap. They are not. My local library has thousands of books not touched on a typical day. The only roads not touched on the typical day are in new developments not ready for building construction to start, once the first building is occupied those roads will also be used every day.

Every given day there's probably dozens of miles of lanes that are closed due to crashes or refurbishment. Probably a lot more than that depending on where you cast your net. Whats another stretch of road going to do on aggregate anyhow? When bridge work or sewer work goes on over these same roads they go down for years too, sometimes totally down with no travel at all, e.g. in LA it took the city 8 years to replace the 6th street viaduct in Downtown LA and traffic was forced to detour for nearly a decade. Yet the sky didn't fall, things carried on basically how they always have with hardly a noticeable impact, and now that the bridge is open today I wouldn't say that traffic in the nearby area has been dramatically changed one way or another. There was plenty of redundancy and spare capacity in the network as it were.

Tell me, if a shelf had to go out for repairs in your local library, would it damage everyone who touches the books on that shelf, or would they simply be moved to a different shelf?

If a shelf was millions of dollars you can bet my local library wouldn't have any more than they needed. Because a shelf is cheap my library can afford to have extra.

Also selves in my library are redundant in ways road lanes are not. If you move a book across the library that isn't a big deal, but if they move the book to a different city that would be a problem. Likewise, even if there was an extra road lane someplace, if it isn't close and going in the right direction it is not redundant.

Concrete alone is 4-8% of global annual emissions, so I would imagine once you factor the carbon impact of destroying, hauling away the rubble, and then making, transporting new building materials, the net impact is not good. There is a reason why most cities are targeting retrofits. https://en.wikipedia.org/wiki/Environmental_impact_of_concre...

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