Construction Costs: Metro Stations

It is relatively easy to come up with a database of urban rail lines and their construction costs per kilometer. Construction costs are public numbers, reported in the mass media to inform citizens and taxpayers of the costs of public projects. However, the next step in understanding what makes American construction costs (and to a lesser extent common law construction costs) so high is breaking down the numbers. The New York Times published an excellent investigative piece by Brian Rosenthal looking at why Second Avenue Subway specifically is so expensive, looking at redundant labor and difficulties with contractors. But the labor examples given, while suggestive, concern several hundred workers, not enough for a multibillion dollar cost difference. More granularity is needed.

After giving examples of high US construction costs outside New York, I was asked on social media whether I have a breakdown of costs by item. This motivated me to look at station construction costs. I have long suspected that Second Avenue Subway splurged on stations, in two ways: first, the stations have full-length mezzanines, increasing the required amount of excavation; and second, the stations were mostly excavated from inside the tunnel, with only a narrow vertical access shaft, whereas most subway lines not crossing under older lines have cut-and-cover stations. The data I’m going to present seems to bear this out.

However, it is critical to note that this data is much sparser than even my original post about construction costs. I only have data for three cities: New York, London, and Paris.

In New York, Second Avenue Subway consisted of three new stations: 96th Street, 86th Street, and 72nd Street. Their costs, per MTA newsletters: 72nd Street cost $740 million, 86th Street cost $531 million, 96th Street cost $347 million for the finishes alone (which were 40% of the costs of 72nd and 86th). MTA Capital Construction also provides final numbers, all somewhat higher: 72nd Street cost $793 million, 86th Street cost $644 million, 96th Street cost $812 million. The 96th Street cost includes the launch box for the tunnel-boring machine, but the other stations are just station construction. The actual tunneling from 96th to 63rd Street, a little less than 3 km, cost $415 million, and systems cost another $332 million. Not counting design, engineering, and management costs, stations were about 75% of the cost of this project.

In Paris, Metro stations are almost a full order of magnitude cheaper. PDF-p. 10 of a report about Grand Paris Express gives three examples, all from the Metro rather than GPX or the RER, and says that costs range from €80 million to €120 million per station. Moreover, the total amount of excavation, 120,000 m^3, is comparable to that involved in the construction of 72nd Street, around 130,000 m^3, and not much less than that of 86th Street, around 160,000 m^3 (both New York figures are from an article published in the Gothamist).

A factsheet about the extension of Metro Line 1 to the east breaks down construction costs as 40% tunneling, 30% stations, 15% systems, and 15% overheads. With three stations and a total cost of €910 million over 5 km, this is within the range given by the report for GPX. The tunneling itself is according to this breakdown €364 million. An extension of Line 12 to the north points toward similar numbers: it has two stations and costs €175 million, with all tunneling having already been built in a previous extension. Piecing everything together, we get the following New York premiums over Paris:

Tunneling: about $150 million per km vs. $90 million, a factor of 1.7
Stations: about $750 million per station vs. $110 million, a factor of 6.5
Systems: about $110 million per km vs. $35 million, a factor of 3.2
Overheads and design: 27% of total cost vs. 15%, which works out to a factor of about 11 per km or a factor of 7 per station

Rosenthal’s article documents immense featherbedding in staffing the TBMs in New York, explaining much more than a factor of 1.7 cost difference. This is not by itself surprising: Parisian construction costs are far from Europe’s lowest, and there is considerable featherbedding in operations (for example, train driver productivity is even lower than in New York). It suggests that Paris, too, could reduce headcounts to make tunnel construction cheaper, to counteract the rising construction costs of Grand Paris Express.

But the situation with the stations is not just featherbedding: the construction technique New York chose is more expensive. The intent was to reduce street disruption by avoiding surface construction. Having lived on East 72nd Street for a year during construction, I can give an eyewitness account of what reducing disruption meant: there was a giant shaft covering about half the width of Second Avenue, reducing sidewalk width to 7 feet, between 72nd and 73rd Streets. This lasted for years after I’d moved away, since this method is so expensive and time-consuming. Under cut-and-cover, this disruption would cover several blocks, over the entire length of the station, but it would be finished quickly: the extension of Line 12 is currently in the station digging phase, estimated to take 18 months.

London provides a useful sanity check. Crossrail stations are not cut-and-cover, since the line goes underneath the entirety of the Underground network in Central London. Canary Wharf is built underwater, with 200,000 m^3 of excavation and 100,000 m^3 of water pumped; it’s technically cut from the top, but is nothing like terrestrial cut-and-cover techniques. The cost is £500 million. It’s a more complex project than the comparably expensive stations of Second Avenue Subway, but helps showcase what it takes to build stations in areas where cut-and-cover is not possible.

Another useful sanity check comes from comparing subway lines that could use cut-and-cover stations and subway lines that could not. Crossrail is one example of the latter. The RER A’s central segment, from Nation to Auber, is another: Gare de Lyon and Chatelet-Les Halles were built cut-and-cover, but in the case of Les Halles this meant demolishing the old Les Halles food market, excavating a massive station, and moving the Metro Line 4 tunnel to be closer to the newly-built station. The total excavated volume for Les Halles was about 560,000 m^3, and photos show the massive disruption, contributing to the line’s cost of about $750 million per km in today’s money, three times what Paris spends on Metro extensions. In London, all costs are higher than in Paris, but without such difficult construction, the extension of the Underground to Battersea is much cheaper than Crossrail, around $550 million per km after cost overruns and mid-project redesigns.

The good news is that future subway extensions in the United States can be built for maybe $500-600 million per km rather than $1.5-2 billion if stations are dug cut-and-cover. This is especially useful for Second Avenue Subway’s phase 2, where the segments between the station boxes already exist thanks to the aborted attempt to build the line in the 1970s, and thus cut-and-cover stations could simply connect to already-dug tunnels. It could also work for phases 3 and 4, which cross over rather than under the east-west lines connecting Manhattan with Queens and Brooklyn. The same technique could be used to build outer extensions under Utica and Nostrand in Brooklyn. Among the top priorities for New York, only a crosstown subway under 125th Street, crossing under the north-south line, would need the more expensive station construction technique; for this line, a large-diameter TBM would be ideal, since there would be plenty of space for vertical circulation away from the crossing subway lines.

There would still be a large construction cost premium. Changing the construction method is not enough to give New York what most non-English-speaking first-world cities have: getting down to $200 million per kilometer would require changes to procurement and labor arrangements, to encourage competition between the contractors and more efficient use of workers. Evidently, overheads are a larger share of Second Avenue Subway cost than of Parisian costs. But saving money on stations could easily halve construction costs, and aspirationally reduce them by a factor of three or four.


  1. Untangled

    Sounds like it was the stations itself that caused the cost problems for the SAS. The tunnel costs, while still high, are much more reasonable. Although I still wonder how the stations cost so much more even when you account for construction inefficiencies, they don’t even look very good – the design is quite generic from photos.

      • Untangled

        Since they used that expensive vertical shaft technique, I wonder if it would have been cost competitive to acquire properties on 2nd Ave through eminent domain and build cut and cover stations under those properties instead? That way it still leaves 2nd Ave open, albeit with one side where the buildings would be gone. It would need to be deepish since it’ll need to avoid basements but given the stations are already quite deep anyway, it won’t be very much deeper. Of course, both techniques would still be insanely expensive compared to just digging up the road but I wonder how the two compares financially.

        And with the eminent domain option, you can rebuild on top of it once the station is done and you can get use it as a very big opportunity for value capture.

        • Alon Levy

          No, it’s Manhattan, the property values are way too high for that. Toronto did that with Bloor-Danforth, but not on Yonge, because property values on Yonge were too high. The Upper East Side is way more expensive than Yonge Street. You’d spend maybe a billion dollars per kilometer just on acquiring property.

  2. Joey

    Is the question of a full length mezzanine relevant if you’re doing cut-and-cover? Or just mined caverns?

    • Alon Levy

      I think it’s relevant mostly to mined caverns. But avoiding a mezzanine allows you to build more shallowly if you do cut-and-cover.

      • Joey

        Maybe if you’re doing full cut-and-cover. If it’s bored tunnels with cut-and-cover stations, the station boxes will have to be deep enough that they can accommodate a mezzanine anyway, right?

    • Eric

      With cut-and-cover stations, you have to dig up the full length of the station anyway. So assuming the tracks are far enough underground, there is no cost to putting a mezzanine in this dug-up space, rather than refilling it with dirt.

      • Onux

        Late comment, but I have to point out that building a large mezzanine is absolutely more expensive, even if station construction is cut and cover. Excavating a mezzanine with bored construction is expensive, but the cost to build after excavation is not zero. Cut and cover excavation of a mezzanine is “free” (because you dig to platform level anyway) but it costs dramatically less to pour dirt back into the hole than to build a finished space.

        In simple terms, if you have a 37,500 sqft mezzanine (50 ft. x 750 ft., the approximate size for SAS Phase 1) then you will spend five times as much on flooring than if you have two 3,750 sqft mezzanines (50×75 each). You will spend five times as much on overhead lights and five times as much on a ceiling. There is some economy of scale (1600 ft. of perimeter walls for a large mezzanine, 500 ft. for two smaller) but you still have over three times the cost. Some cost is non-linear the opposite way. For five times as many sprinkler heads you can’t extend a 4 in. pipe from 75 ft. to 375 ft. – providing five times the flow means 10 in. pipe for 75 ft., then 8 in. pipe for 150 ft., etc, all at a greater cost than 4 in. pipe.

        Excavation is expensive, but building anything is much more expensive than backfill. Reducing mezzanine size will lead to less expensive stations.

        • Comradefrana

          “Excavation is expensive, but building anything is much more expensive than backfill.”

          With backfill you need to make the station structure stronger in order to support the weight of the soil, is that necessarily cheaper?

        • Eric

          How expensive can building be? You pour concrete to make walls, and put ceramic tiles on them. You put a few lights and sprinkler pipes overhead. I have to assume these costs are negligible compared to other costs of building the station.

  3. Joey

    Curious if there are any recent examples of full cut-and-cover construction (I know LA’s Crenshaw line has about a km of cut-and-cover, but that’s pretty short and has no stations, so might not be very useful for a cost comparison)

      • Untangled

        The Canada Line is literally cut and cut, even where it would have made sense not to. Eg, near Queen Elizabeth Park where it takes a curve when they should have brought a roadheader and dug a short, straight tunnel.

      • Joey

        Ahh yeah! The Canada line also seems like an instructive example in avoiding mezzanines where they aren’t necessary.

          • Eric

            Here’s the track map for reference:

            With automated trains, is their any need for “complete double track” (it already seems double tracked except at the terminal stations) or tail tracks?

            And since Vancouver is a relatively small city, with automated trains providing high frequencies, is there a need for long trains?

          • Untangled

            The Canada Line runs parallel to the old freight Arbutus Corridor so they will build light rail there to support the Canada Line.

          • Eric

            But there are two termini, which means you only need half the frequency at each terminus. According to that site, the termini allow for 80 second headways on the common section. The common section couldn’t achieve better headways than that in any case.

  4. ckrueger99

    What’s your guesstimate on cost for infilling 10th Avenue station on the 7 Line?

    • Alon Levy

      Right now? I don’t want to even think about it. I don’t know of any example of cut-and-cover infill to an already-dug tunnel, even if it were possible to shut down service during construction (which it is, but the city will be too embarrassed to allow it).

  5. RVA_Exile

    To play devil’s advocate, your proposal raises some equity concerns. The white Upper East Side got bored stations, whereas black and brown neighborhoods further uptown would have to deal with the far more disruptive method.

    • Alon Levy

      I’d argue it the other way. 96th Street got immense disruption for the launch box, and 86th and 72nd got localized disruption for many years. What I’m proposing is an 18-month process for 106th and 116th.

    • Eric

      Delaying SAS Phase 2 (or not building it at all) due to cost issues raises even more equity issues.

  6. adirondacker12800

    it was 40 years ago, the recollection is kinda hazy: When they were digging up Second Avenue, for the parts that are still waiting to be used, the trench digging moved along relatively fast. On one side of the Avenue. It got covered. With 8 by 8 wooden beams if I remember correctly. Then the other half was done. Two or three blocks at a time, again IIRC. The wooden street was there “forever”. It was very noisy, very slow and dusty. There are alternatives. I assume they didn’t use them because they are more expensive.

  7. Adam

    Look at the Los Angeles metro red line subway:

    4.5 billion total budget for 16.4 miles with 14 stations

    Phase 1, four miles long with five stations (in the notorious and expensive downtown excavation conditions that have stymied the budget for the current under construction regional connector), and a budget of 1.4 billion

    The remaining three phases with 9 stations and 12.5 miles of construction were built for 3.1 billion.

    That’s right, Los Angeles decreases costs as time went on. They went from 311 million per mile to 248 million per mile.

    And the red line is expensive style station construction.

    I’d say the cost difference for the United States is mostly made up in the executive suite: with excessive hiring of conflicting, over priced, low productivity consultants delaying timelines and driving up costs.

    If we banned and abandoned the consultant system and demanded that all work be done by staffers, the United States could probably have comparable costs to Paris.

    • Michael James

      Adam 2018/01/30 – 17:37

      I’d say the cost difference for the United States is mostly made up in the executive suite: with excessive hiring of conflicting, over priced, low productivity consultants delaying timelines and driving up costs.
      If we banned and abandoned the consultant system and demanded that all work be done by staffers, the United States could probably have comparable costs to Paris.

      Precisely. That is what I pointed out in a comment to Alon’s article in CityLab, citing what Brian Rosenthal pointed out in the NYT article: (emphases are mine)

      The Most Expensive Mile of Subway Track on Earth .
      By BRIAN M. ROSENTHAL, DEC. 28, 2017

      And The Times observed construction on site in Paris, which is building a project similar to the Second Avenue subway at one-sixth the cost. … In Paris, which has famously powerful unions, the review found the lower costs were the result of efficient staffing, fierce vendor competition and scant use of consultants.
      Consulting firms, which have hired away scores of M.T.A. employees, have persuaded the authority to spend an unusual amount on design and management, statistics indicate. Public officials, mired in bureaucracy, have not acted to curb the costs.
      A Times analysis of the 25 M.T.A. agency presidents who have left over the past two decades found that at least 18 of them became consultants or went to work for authority contractors, including many who have worked on expansion projects.
      Soft costs for East Side Access are expected to exceed $2 billion. The project plan called for the hiring of 500 consultants from a dozen different companies, according to a 2009 federal oversight report.
      Both the Second Avenue subway and East Side Access projects hired the same main engineering firm: WSP USA, formerly known as Parsons Brinckerhoff. The firm, which designed some of New York’s original subway, has donated hundreds of thousands to politicians in recent years, and has hired so many transit officials that some in the system refer to it as “the M.T.A. retirement home.”
      The firm was the only vendor to bid on the engineering contract for the Second Avenue subway, records show. On East Side Access, it is sharing the contract with STV Inc., which recently hired the former M.T.A. chairman Thomas F. Prendergast. The contract was initially for $140 million, but it has grown to $481 million.

      Hiring Predergast looks like excellent value as it grew their contract by 340%. Another CityLab commenter noted that the MTA has a 2 year exclusionary clause after they leave the MTA, however Prendergast was Chairman into 2017. Perhaps the only way to break this revolving door is to make it a lifetime ban on ex-MTA employees working in the private sector on MTA projects.
      I have written at tedious length on this issue on this site:
      Michael James 2017/08/14 – 07:07

    • EJ

      LA normally builds stations using cut and cover, so the relative expense of building a mezzanine is not as much (since you have to dig down anyway) vs. mining it out like NYC.

      • Onux

        See my comment to Eric above on why using cut and cover does not dramatically reduce the cost of putting in a mezzanine.

  8. FlavaNation

    From a political perspective, I think it would be extremely difficult to close 1-2 complete blocks of Second Avenue, even if it’s just 6-12 months (lol six months). Second Avenue is an important SB through route on the upper east side. If you closed 1-2 blocks, you’d have to reroute buses and trucks. Overall, you’d have only two SB only Avenues, with Park Avenue being two-way. The two other SB routes are Lexington and Fifth Avenue. Also consider truck routes. No, you cannot re-route trucks onto Fifth, so that means you’re only left with Lexington Ave as your SB through truck route.

    • adirondacker12800

      Again, if I am remembering correctly, traffic never stopped. It just slowed down. Close the east side of the avenue while the wooden roadway is constructed and then swap sides. Then a long period when the whole avenue was paved with wood.

    • Alon Levy

      In the cut-and-cover era, roads were closed half-width at a time. I don’t know whether that’s how it’s done at stations here; the examples I’ve seen are not on major throughfares.

      I also think First and Second should both be made two-way, but that’s a separate discussion.

      • Eric

        Why, pedestrian safety? Because I’m pretty sure street capacity is higher with one-way. Less stopping at traffic lights.

        If you don’t want to encourage car usage, you can make the streets one-way and narrower.

        • Alon Levy

          Buses specifically benefit from two-way streets over one-way pairs, especially widely separated pairs like 1st/2nd or Nostrand/Rogers. It’s easier to remember where the bus goes when it’s a two-way street, and easier to set up transfers with crosstown buses without requiring the crosstown bus to stop every block.

  9. anonymouse observer

    Do you think if NFPA 130 is one of key factors on overbuilt subway station in North America?

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