The Fast Way to Build Subways: Cut and Cover

Subways used to be built in just a few years, and they used to be built with cut and cover construction! But what is cut and cover, and should we go back? Find out in today's video.

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Ever wondered why your city's transit just doesn't seem quite up to snuff? RMTransit is here to answer that, and help you open your eyes to all of the different public transportation systems around the world!

Reece (the RM in RMTransit) is an urbanist and public transport critic residing in Toronto, Canada, with the goal of helping the world become more connected through metros, trams, buses, high-speed trains, and all other transport modes.

[RMTransit]

If you want to hear more about how different construction approaches can send a project off the rails, read my latest blog post here:

[FalconsEye]

This is how something like 90% of New York stations were built, some people wonder how so many were built giving it takes so long to make just one today.

[deanlemckeevans]

cut and cover also provides the city an opportunity to improve other infrastructure that goes under a street like water pipes

[francoiss]

The Melbourne Metro Tunnel used cut and cover for its stations but it built huge sheds over the stations so that dust and sound were dampened significantly. It also allowed them to add windows in so people could see the stations progress and arts on the sides while using TBM’s in between stations. It was a really nice idea and you really couldn’t tell there was so much construction happening right under you.

[wilfstor]

Whenever my parents question why it takes so long to build subways these days I always comment that "It's no longer acceptable for an Italian immigrant to die every kilometer any more" which always makes them realize how far safety rules have come in their lifetimes...

[ethanstearns]

This video is absolutely correct, but also the issue with North American transit construction is not just the construction methods, it's everything else. The Maryland purple line for example uses cut and cover for its underground portions, a mostly above ground preexisting right-of-way, and its still been delayed over and over again!

[neolithictransitrevolution]

With the REM and Ontario line, Toronto, Vancouver, Montreal, and Ottawa will all have built elevated transit lines in the last decade. A good sign for building experience and things to come.

[michaelmains]

As a tunnel designer who works on transportation projects I think this is an excellent, well articulated opinion by someone who clearly has a deep understanding of subway construction. Well done.

[MultiRanman]

The cut and cover method seems to work best is situations where, naturally, want to go in a straight line under a street. It’s probably the best option and why cities used it initially, especially under many streets in NYC.

[unlapras]

I notice that in my country (France) cut and cover is no longer an option, even where it would be technically possible. We just build everything with TBMs regardless of whether it's justified or not and stations become needlessly deep and expensive to build. Unfortunately I think the fear of NIMBYs is the main explanation. In Paris a very short cut and cover section had to be built for line 1's extension just to launch the TBM and yet the whole project might be cancelled because locals refused it.

[amdsemporn]

In my city in Germany, cut and cover is a huge pain, because they will definitely find remains of the romans from 2000 years ago, halting the complete operations

[tramcrazy]

A good example I think is London, the old sub surface lines were built with cut and cover but they completely dug up the streets to do it. I’m not sure people would accept that now. Also cut and cover is very very hard to do where buildings are present.

[scottydude]

One construction project in the US that could totally be done with cut and cover is the Roosevelt Blvd Subway in Philadelphia. Alan Fisher has a good video on it that I would suggest watching

[AaronSmith-sxez]

Cut & Cover is definitely the gold standard for rapid transit expansion and I wish it were used more. But one downside of building under streets, is most modern cities put most of their utility conduits there (sewage, water, fiber, electric, gas, storm water, etc). So the main cost usually isn't ripping up the street and digging a hole, but relocating all those utility connections which can be costly. But in many cases IMO it can be worth it because cut & cover is so much more efficient. NY doesn't have the rapid transit system it does today if not for cut & cover. If they originally built deep tunnels the walk times to the stations would have been too much and far fewer people would have used it.

[paulallenpatriarca]

I started watching your videos 4 years ago and now, I'm a graduating railway engineer in my country. Thank you for always giving me valuable insights.

[vlaardingerrr]

Another reason for not choosing cut and cover is that u have to move all the underground infrastructure as well. Sewer, phone, electricity and water. The hardest and most expensive to move is the sewer pipe, the fall must be consistent, sewer doesn’t like going uphill/around the new metro line. For the Canada line in Vancouver; probably the underground space had been “reserved” for a few decades in anticipation for the metro line. Because of the reserved status the underground space have been kept empty.

De streets which are wide enough for cut and cover are most of the time the bigger access roads. Most of the time underneath those roads are the main pipes and cables for the whole neighborhood.
Keep in mind a metro line travels a long distance through the city. And Because of the size and the inconvenience of not having water/power/sewer in the whole neighborhood the builder have to move the pipes and cables multiple times.
They know there is something underground, but they don’t know where precisely and how deep. The drawings they do have are old, when the neighborhood was being build. Those old drawings are not that detailed and also outdated. Some changes which have been made over the years have been lost. The other problem with old drawings is that u can’t read them because it’s copied/edited and printed too many times. And with the lack of detailed information try to make a plan for moving those cables and pipes multiple times. And try to make a new connection with a sewer or water pipe from 1960, it probably will fail. This all is way too hard and expensive. It’s much easier and cheaper to dig a square hole once in a while for a elevator shaft.

[henryostman]

Good video, made a lot of sense. We need to remember that our toolbox has grown over the years, back in the day they didn't have TBMs and a lot of digging was done with a pick and shovel. A big problem today is all of the stuff that is buried under the street, used to be just the water lines and sewers, now we have electrical lines, telephone, cable, telegraph?, and steam lines for building heat. And, believe, a lot of this stuff isn't very well mapped, you dig and find stuff that wasn't supposed to be there. Remember too, that horse and wagon transport had a weight limit of less than ten tons, todays trucks weight that much empty. So, get a TBM and dig deeper, under the first and second layers. Then you have other problems, DC was a swamp and really still is, they just paved over it. You generally have to dig out the stations but that big hole fills up with water that you have to pump out, but dewatering destabilizes the foundations of nearby buildings, resulting in a lot more work. Your comment on transit moving a lot of people with NO pollution is like the claim for electric kars, yeah, there is no tailpipe on the train but where do they get the juice? Probably a coal fired station up the river a few miles.

[jan-lukas]

As always: build stuff overground! It's always cheaper than building tunnels

[nicolasblume]

An important factor is street width: If the street is quite narrow, cut and Cover might not be feasible for the whole route.

[Globalurb]

I agree, cut and cover is a method among many others. Besides disruption (see initial Yonge subway construction trauma), theres is also a cost to deal with existing underground infrastructure. Builders are forced to relocate, temporarily support or be extremely careful with (using extremely expensive methods) existing infrastructure.