The Fast Way to Build Subways: Cut and Cover 

I suspect that TBMs are used instead of C&C when C&C would be the better option is because of NIMBYs...

C&C gets a lot of flack due ot the piling required to do the ditch walls. Reaction piling systems (such as the silent piler by Giken, no affiliation) have done away with the large space claim and environmental impact typically associated with piling projects. I recently got to see a demo of this type of system stabilizing a property by a river and it was truly quiet - with a sound attenuated hydraulic power unit/generator as the biggest noise source, one could still have a confortable conversation without yelling 20 feet away. The loudest sound in the site was the warning beepers from the trucks bringing in the sheet piling. Smaller TBMs (microtunneling, likek those produced by Herrenknecht and others - again no affiliation) still like to have launch pits which will require some cut-cover/trenching. Each tool has its job.

I just ordered that book you recommended "How Big Things Get Done" and it's the best thing any urban planner or civil engineer can read to learn how to get projects done on time

Tunneling for East Side Access, the 2nd Avenue subway and Crossrail were all mostly trouble-free and the fast part. It's the installing of track, wiring and life safety systems that seems to cause years of delay and budget overruns. Whether a new tunnel is cut-n-cover or a TBM to avoid utilities, isn't the problem. Very bad management is why we can't have nice things anymore.

@@fredashay TBM’s are often cheaper and certainly less disruptive. Cut and cover is viable for short sections where there is a usable corridor that can tolerate years of extreme disruption

Like the wooden slats strapped together that Boston's Big Dig found (with water flowing through). 😂

That's a bit of a double-edged sword, though - cut-and-cover means you HAVE to revamp any under-road infrastructure, which can add a lot to the costs (particularly when you have to relocate things like high-pressure gas mains)

That’s true but generally I think bundling like this is a bad idea

@@benlever3172 should be done anyways. Yeah let’s drink from lead water pipes

​@@williamerazo3921 Flint vibes coming up

It's nice that your parents appreciate your interest in Transit, my mom just yells at me and tells me to get a job

@@saltysea3626 Depends on Your age

Idk lots of countries build transit fast and safe (spain turkey for example)

@@hypernewlapse This ^^^. Countries are able to build quick without compromising safety.

I bet it was more than one death per km.

Then I guess the problem is the tracks and tunnels since the alignment requires tons of urban and environmental planning and trade-offs

Yes! But it’s not just that, as I discuss :)

Most of the remaining elevated lines were built before those neighborhoods were fully developed.

Most of NYC was built like this in less 40 year time span. Only China can do something like this at a fast pace

It always blows my mind how shallow the 1 train is, especially at 59th street where you can can see people walking on the street from the giant entrance on the uptown platform

I thought at least some of them were mined?

@@RMTransit The 2 CBD stations only access shafts were build, with mostly sheds over them, and the section of the station between the shafts were mined. The other 3 stations or mostly cut and cover.

@@RMTransit I think they're doing cut and cover for the stations in ... Auckland NZ, and TBMs for the lines

In some ways yes, but the prices are still going up!

I thought they are using boring machines like in Bethesda. I'm be glad when the crossing of Kenilworth ave for the Riverdale elevated station. I'm tired of driving passed it and seeing the same thing. Seemingly not much seen work being done.

@@Steve-tj9on I've lost all hope for DMV projects anyways. Silver line started back in 2007 for context, and it didn't finish until just recently...

I think this video vastly underestimates the cost of cut and cover. It might have been cheap to do in the olden days, but these days it's not as simple as closing the road and deploying the largest excavators you can find. There are fine webs of infrastructure for power, internet, water/sewage etc. under any moderately urban street. Just working around that infrastructure hampers excavation efficiency drastically. If you need to move/realign a bunch of stuff that crosses through were your tunnel is going, that adds even more to the bill. Not to mention having to stabilize the sides where there is no space to dig at an angle - which is insanely expensive. Tunneling is ridiculously expensive indeed, but apart from geological factors, you are unlikely to meet any surprises.

That’s because these days, it’s legal for any NIMBY to sue to stop a project using BS environmental concerns

Of course, the project organization is a huge issue! See the pinned comment for more

yeah, this. Realistically it's just not practical on many routes. LA is a great example as it uses both in different situations!

Elevated or grade-level trackage?

Unless there is nimbys in the way haha

@@apexhunter935 grade level is much cheaper, but eliminate at grade crossings as much as possible. That is how Japan managed to still operate most rural lines.

@@Jason-gq8fo if they are simply reactivating lines, they can't do much I guess

Through whose neighborhood?

and thats just the harmless stuff. unlike most cities in north america, in german cities you can and do ocasionaly find unexploded ordinance from the second world war.

As a person who lives in an area with 5 tunnels crossing major bodies of water i was wondering if you know how they are doing on the new Hampton roads bridge tunnel? Serious question. Are you working with that one or do you know anyone who is?

Tunnel boring isn't so horrifically expensive anymore. The Elizabeth Line spent a small fraction on boring, and most on stations. All those utilities, and disruption to the city, can be reasons to prefer boring in many cases. (An aside on moving utilities, the Big Dig in Boston came across centuries old water lines formed by wooden slats strapped together...with water flowing through them.)

@@bearcubdaycare But the problem with deep tunnels is deep stations and long walk times. Long walk times are a hidden killer for rapid transit systems. In MY, many stations are just a 30-40 second walk from the surface...which is a hidden reason NY has a such a popular transit system. On the flip side China is completely oblivious on this issue and crazy long walk times (and security) will hurt many of China's rapid transit systems from reaching their true potential.

Tunel borinfg went a long way since the 50's or even the 90's The TBMs that dug Warsaw Metro's line 2 in 2010s were moving roughly 5 times as fast as the one that dug non-cut and cover parts of line 1 in 1990 and early 2000s. Cut and cover still can be faster given favorable terrain, but a lot hangs on other factors.

Idk! Vancouver has under road utilities and managed to figure it out!

If so, how did London ever survive the switch to deep level tubes?

cnc at Main-Quebec, Yukon-Cambie, Maple-Arbutus...

Must be nice to have a little condo and a car and have the city bow down to you at all times. We have to tunnel a hole through the ground not like the whole city is a grid and there is 4th, or 10th, or 12th, or 16th, or 25th to head east or west. Broadway could also EASILY have dedicated bus lanes going both directions but instead buses have to wait in traffic so that 15 people can park on the street instead of using a side-street or a parkade.

There are cut and cover subways beneath narrow streets where the builders decided to stack the two tracks on top of each other. It's definitely possible.

@@n.bastians8633 Good examples in Frankfurt: Merianplatz, Höhenstraße, Bornheim Mitte and Leipziger Straße. Incidently, all but the latter (which is below its namesake, Leipziger Straße) are located on the same street (Berger Straße) but they all are one-way streets with street parking at most.

I think part of the reason why north americans (who are transit fans) will go to the extreme of wanting no new highway building is because north america already has tons of highways - we don't need more. Toronto for example has 3 east-west highways and 4 north-south highways. As far as circular highways, you seem to be unaware that the vast majority of cities in US & Canada already have them. Toronto's is the 407 (it's a half circle because of the lake, but whatever), and it's a huge failure on a regional level because the toll is too high. And the toll is too high because the Conservative provincial government of the 90s are idiots and sold it to overseas investors who don't care if the city functions well. I call it a failure because parallel routes like the 401 or Highway 7 have still needed to be widened or turned into highway-like arterials. Now there is demand for Highway 413 which is yet another highway parallel to the 407, all because the 407 never worked and the province never provided a decent non-automobile way to travel east-west in the GTA other than Lake Shore GO, which is literally 15 km south of the 407. You say that Tokyo has surprisingly decent car traffic. Yes, because there is so much good transit that there is no reason to get involved into traffic congestion. Not because they built a lot of highways, but because their ratio of transit to highway & arterials is so much more tilted towards transit.

@@trevorvanderwoerd8915 part of ur argument is true, however ‘city circular highways’ isn’t usually something that only exists just one in a mage city. Take Beijing for example, they have five and as far as I know there might be even a sixth one at some point in the future. Toronto has something very close to a city circular highway, true. However, between DT and Midtown area there are supposed to have one more highway to form something so called ‘the first circle’ to mainly serve DT area, and I’d say that the don valley highway should have the second bridge to serve the people who only passes DT but not getting to DT. There is 407 true, and it’s a big failure also true. But even including 407 as if it’s a free highway, only three highway to serve the East to West of Toronto is way too less to be honest especially for Toronto as how strange the city management is, and plus 407 is mainly served to rural suburban areas like Richmond hill or Markham. You don’t need to make a huge highway that has 20 lines in it like 401, the traffic will still be there. But what u really need is multiple highway to serve people who goes different directions and also not making any highway too over densely used. And btw, Japanese do drive, whatever the fantasy that North American have about ‘European or Asian’ don’t drive is just pure nonsense. Maybe not as much as North America, but most of us do have cars and many of us, we do drive to work. We just normally have a better and more complex transit system than you guys that whenever we don’t want to drive, we might get the chance to use another method to go to work. But it doesn’t mean we don’t drive or we hate driving. In fact, driving is a very popular culture in Japan.

@@trevorvanderwoerd8915 I guess the whole point is that building highway does not conflict with building public transportation and the idea of relating building infrastructure with politics should be stopped. They are parallel and can be processed simultaneously. Just because we should build more public transportation doesn’t mean we should get rid of all the infrastructure. Do I support building more public transportation? I definitely do, but I do also support build more highway and improve infrastructure. And in fact, I think that Toronto, or most of the North American cities in general should get rid of Plazas and single houses so that those huge waste of land can be re-use to make a better used and more densely populated city so that infrastructure and public transportation can be better and easier to build to serve the city as a CITY instead of the typical NA city that we got now. Honestly I’d say that outside of DT and few other densely populated areas, most parts of the city are more like ‘Desakota’, if u don’t know the definition search it up. Lmao

@@Seibanori Only the outer 2 of Beijing's 5 ring roads are completely grade separated though; the inner 3 still have at-grade intersections, but fewer in number e.g. by having underpasses/bridges

@@lzh4950 well, that’s probably because when they built the inner 3 rings, the main land China was still in a very early development stage and they probably didn’t think that the traffic will ever gonna be that bad. And another thing is, once ur population is getting to a certain level, no matter how many highways or subways u build, the trafficking will still be there. It’s just inevitable. Take Beijing for example, it has more than 20 million population. It’s just gonna be there.

Well, before you start taking the actual local situation into account, anyway.

Seattle's North & University Link should have been this way... twice as many stations from Downtown to Northgate. Also they wouldn't be so deep and so reliant on always breaking down deep elevators and banks of escalators.

And express services often take a more direct route compared to non-express services which take a less direct route. If it means to build a tunnel below buildings then you'd never want to use C&C there.

@@jonw999999 The huge gap between Capitol Hill and the University of Washington always looked weird to me.

10 m per week is awfully slow. That's just half a kilometer in an entire year. You would need to start work at multiple sites simultaneously if you wanted to use that method. TBMs can move at 20 to 30 meters per DAY.

@@wasmic5z The other beauty of cut-and-cover is that you can have multiple contractors working at same time. Also the operation is simple and conventional so all cities have multiple contractor who can do the work. With TBM, the entire thing must be finished before any station construction can start since the under construction tunnel must be used to remove the dirt.

@@walter2902 Here in Copenhagen at least, they're already building the stations while the tunnels are being drilled. Work on the stations continuous from the start of construction until the end - but the station just takes a lot longer to build than the tunnel does, so in the end the tunnel still gets finished first. Most of our metro is built with TBMs, but there are a few sections of cut and cover too. Obviously, both methods have their pros and cons... but in Copenhagen speficially, there are very few straight wide sections that are suitable for cut-and-cover.

The pollution from EMUs is far less per passenger than an electric car, but even from renewable energy it is never absolutely zero pollution.

The did Cut and Cover in Milan and Vancouver, there’s city’s above in these cases too!

They did cut and cover in lower manhattan’s in 1910s when it was becoming the central business district at its time. Look how they built the 6ave line subway at 34st. That’s called disruption.

In China cut and cover stations are pretty common with TBM bored tunnels AFAIK. It's the best of both worlds really.

Honestly, C&C stations should be the default unless local restrictons, lest because a hole has to be made for the TBM and all the excavation anyway.

@@MarioFanGamer659 question is, how do the costs compare? You may need to cut more than just an intersection depending on the size of said intersection, which would get into eminent domain. So like elevated and indeed cut and cover subway, cut and cover stations work best on stroads. Dream scenario is cut and cover a whole stroad and turn into a pedestrian street.

I thought this too. I think that the likely hood of finding anything goes down exponentially the deeper you go. Because those TBMs dig so far down I wonder if they just don't run into anything except rock and dirt down there.

@@fallenshallrise thanks for your reply, I'm glad it wasn't just me 🙂 The reason I am curious is I am living in Melbourne, Australia and we recently have had Four boring machines tunnelling through our city. Two for a dual tunnel (ahem) "Metro" train line (which Reese has done an explained video), and another two as part of a Vehicle Freeway tunnel project (Westgate Tunnel). While yes they do reach significantly deep that is still four tunnels that have to rise in and out of ground level at some point using gradients sufficient enough for the job. So it just had me wondering, can we blast away the most preserved triceratops and never know it. Is it even a consideration. I am not banging on about conserving this and that... just genuinely curious.

Elevated lines are way cheaper and faster than underground. Thats why Asian countries like India are building them above ground.

Or you just freeze the surrounding around the concrete tubes, they have used this method here for decades. They also use freezing when digging into the ground in material that can be loose, freeze it and it is stable to work with, btw they freeze it for a long time like in more than a year. The construction method chosen depends on the circumstances, not all construction sites are the same.

Indeed, I would say that the disruption of cut-and-cover is one of the reasons we moved towards using bored tunnels. In the case of NYC, trying to do the large-scale cut-and-cover operations that gave them the subways to begin with would probably result in a flurry of lawsuits from business and property owners, community groups, and motorists claiming negative impact. Not that avoiding C and C solves this; bored tunnels are being used in Seattle and local residents still claim the disruption will "destroy their neighborhoods" and residents of Bel Air in Los Angeles object to a very deep bored tunnel under their neighborhood, mostly on principle (despite not having a station there or any real impact), but ostensibly that it would be a cave-in danger, somehow.

I included pictures and discussed this in the video, we’ve improved these methods a lot in 70+ years! It’s not reasonable to compare how we did things in the 50’s imo

I mean, Vancouver did it

@@Skip6235 Sorry, I don't know about the specific situation in Vancouver. In the case of Washington DC, a lot of it was done using cut and cover (at least the stations were), but the part of the Red Line on a steepish grade had to be done using a bored tunnel.

Who cares about the disruption, they got paid for there disruption and got canada line built before the Olympics on time and on budget

NA political culture (at least US & Canada) makes transit projects difficult in general. Some train lines which should be surface or elevated end in up tunnels (to appease NIMBYs), and some which should clearly be tunneled end up as surface lines (to appease budget hawks). Out of the scope of this video (a bit), but transit projects are often portrayed as stalking horses for "gentrification" and as having a negative disparate impact on different communities. Highly visible disruptions like cut-and-cover are often used as an example of this, but that doesn't get things like bored tunnels "off the hook" with transit opponents, either (bored tunnels can create their own types of disruption).

I always wondered if the fact that there is no station at 12th or 16th along Cambie is just revenge for those bushiness that worked so hard to try to block the construction that benefits thousands per day.

i thought the broadway ext is being made by cut and cover

@@dashthecat0 only the stations

Just as the businesses on Eglinton Ave. in Toronto went out of business due to the extremely deep cut-and-cover stations created from the TBM tunnels.

The damage to the buildings on the Vijzelgracht was caused by the building of the Vijzelgracht station - which used cut-and-cover. The tunnel boring went without a hitch, including the bit where they slid a whole metro station under the Centraal Station, while the station remained open, and having to cut some of wooden foundation poles in the process. It really was a triumph of engineering.

It's actually interesting D/R is C&C since it's located right below some buildings which is untypical because they'd be demolished to make way for the station (one of the station entrances is even located inside one of the buildings). OTOH, the old city had to be reconstructed anyway so there were no buildings in way.

I'm pretty sure the Northern hub of the GPE, Saint Denis Pleyel, wasn't built with box + TBM but with the TBM + box method. That's sounds like the same thing but it's actually the other way around : tunnel first, box later. I've seen pictures and videos where they dig around the recently built tunnel and "unbuild" it when they reach the right depth. And in the case of this hub station, they also reversed the order of "cut-and-cover" for the station box and used mostly "cover-and-dig", and repeated the operation for every level. There are other stations in the same case but I don't remember exactly which ones. One station in Paris that has quite a unique and remarkable building method is the new la Defense station for RER E that is due to open later this year : it was built like a mole, from under the massive CNIT triangular building, creating new reinforced and much deeper foundations while the building functioned normally above. Plus, the station is pretty cathedral-esque, with a massive mezzanine above the platform, forming a huge void under the somewhat historical structure of the CNIT expo center. Weren't the new extension and stations on the North end of M12 built with a TBM and box method? From what I heard, RATP and its contractors used the cut-and-cover method on line M4's South extension with a hefty dose of regrets at certain locations. It apparently was due to the horrendous cost, delays and complexity of utility realignment, the famously hollow Swiss cheese that is the shallow Parisian underground, riddled with quarries and gypsum layers, and the systematic vicinity of some very loosely defined aquifers. Anyway, building a subway line in Paris is always quite challenging, not to say nightmarish, whatever the chosen method. They had to freeze the ground on the last phase of the M14's North extension tunnel, near the hub if I recall correctly. It was due to the rather bad location of the mandatory emergency exit & ventilation shaft, if memory serves. They also endured a surprise flooding, but I can't remember which line extension it happened on. They also had many similar issues when building M12's North extension. And bam ! Several years of delay and a nice big cost overrun but now it's open. There aren't many infos yet but from what I gathered, the East and West parts of M15 will use a selection of different methods to build the stations, so as not to encounter the same issues in a seemingly more complicated and less welcoming terrain than the M15 South section. Saint Cloud station will be one (of several) to watch for, as I doubt they'll use the common box technique there. As for M1 Eastern extension, they may have to resort to a different technique than the initially planned cut-and-cover method for the Vincennes underground junction. Local opposition and environmental concerns (tree cutting) have ballooned and probably contributed to tip the scale on the negative judgment of public utility. There are also important concerns about the massive underground junction in Rosny.

Yes, Paris still mostly builds its stations using C&C but not tunnels. Stations are vaulted only when it is technically impossible to dig a trench above the tunnel, like on line 14 between Saint-Lazare and Châtelet due to the line being built below apartement blocks.

@@KyrilPG Yes there are two methods for box and TBM, the Top to Bottom (digging from the ground to the bottom of the trench) and the Bottom-Up, (digging like mole from the lower levels up to the street level. Line 12 had to resort to freezing around Aimé Césaire station extremities near the Ourq canal because the ground was not stable enough but they messed up with the usual salt water method and resorted to EXPERIMENT on liquid nitrogen instead, starting again TWICE because they messed up the first time (three attempts with the two methods combined) leading to a severe delay (4 years + 1 year due to Covid restrictions. Line 14 had to freeze terrain under RER C tunnel in St Ouen, it was one of the last pieces of tunnel made for the St Ouen extension and it went pretty quickly. The delay was due to flooding in Porte de Clichy station box because... all of the water that the new tribunal's foundations displaced. That wasn't accounted for until it was too late because the metro building works began with a delay letting the tribunal being built first when it was supposed to be built after the metro. The delay was due to decontamination of the St Ouen terrains where the new line train maintenance depot is while it used to be an oil refinery, Total not wanting to clean their mess when RATP bought the terrain had to settle the issue in court (Paris Administrative Court) which decided that BOTH companies should work hand in hand for the site's decontamination since none of them wanted to take charge...) leading to two or three years delay. Part of Line 12 extension delay was also due to Veolia Sewage department not willing to actually MOVE the sewers prior to the construction work as it is traditionnally done. St Cloud will be built in a hill, the terrain there has some severe slopes and cliffs for an urbanized area One example of stations built with the TBM going through first was Châtelet on Line 14, that's why its ceiling his higher than the others because they were building it while the TBM was passing just under the work site ! Line 4 construction in Bagneux actually damaged nearby condo buildings because of excessive vibrations, leading to works stopping to stabilize the said buildings. Anyway, the place will have a big metamophosis, new buildings being built at once with the GPE station anyway... Rosny Line 11 terminus was very simple to build, just under the shopping center car park on the other side of the RER station, however, they changed the plans for the line new train depot and workshop several times before settling on the definitive place and access tunnel supposed to be before the station, along the tunnel to Paris before being settled after the station, leading a possible connection to the future extension to Noisy, if it is ever built, that is (local politicians seem to recently want to ressurect the shelved project). Geology is ine thing, political shenanigans are as nightmarish as geology in Paris (and not just Paris, London or New York had their fair shares of those as well...) Noisy didn't want the T1 tram to be extended through the city center because it would take too much space and damage the shops's clients visit potential... so the tram will make a detour on the outskirts to serve future neighbourhoods instead. Same in Colombes, future Western T1 extensions will avoid a small avenue because the Fire Brigade department was unwilling to change their procedures for the tram overhead wires and local residents didn't want to share the road with the tram, so it will make a detour North via the outskirts and future neighbourhoods as well... At least it could serve the interests of a possible GPE extention on Line 16/17 to Nanterre with a station in Colombes to be really efficient, fast and complementary to the tram. Not every shenanigan will lead to a nightmare, some can have benefits...

Subways are usual built under roadways. So having a bridge with a roadway on the top deck and a subway bridge below would work.

Many cities have built subways using cut-and-cover to dig underground and submerged caissons to build tunnels underwater.

Immersed tube is sort of like cut and cover