Northern Line Extension TBM

The $234,650,000,000 (two hundred thirty-four billion six hundred fifty million) subway

In 2018, I declared the New York City subway system “the best”, based on the factors considered.

Cities like London or Moscow have had their subway networks in place for over 100 years. Although both have grown in the intervening time.

Modern day cities like Shanghai have built comparatively new and large systems at an astonishing rate.

New York is planning to have spent around $35 billion between 2005 and 2030 on subway and commuter rail expansion. But itโ€™s only getting 15 km of new tunnel!

Paris is spending a similar amount over the same period: โ‚ฌ40 billion, for a total of 228 km, 187 km underground.

Madrid, a much smaller city, spent โ‚ฌ10 billion in 1995-2015 on 234 km, around 180 km underground.

Let’s take a deeper look…


Pedestrian Observations (Alon Levy) has compiled a comprehensive presentation titled; “What is the Cost of Building a Subway?“.

The figures used for my analysis are taken from that presentation, which uses data from an unreferenced dataset of different urban rail lines and their costs.

According to the presentation, “Costs cover engineering, contracts, and political factors.”


Approximate construction costs by region per km, in millions (USD)

Download chart.

Country / Region USD million/km
East Asia 100
Turkey 100
Mediterranean / Nordic / Switzerland 120
Chile 150
Iran 200
Western Europe 250
China 250
Mexico / Brazil 330
Thailand 475
US / Canada / Australia / Singapore / UK 500
Philippines 1000

Download table.

Think infrastructure project in the Europe / US are expensive?

In Manilla, Philippines, they’ve spent and estimated $1 billion USD per/km. Twice as expensive as the US / Canada / Australia / Singapore / UK ($500 million USD per/km).

Halve that by building in Western Europe. $250 million USD per/km.

Head to Mediterranean / Nordic countries, or Switzerland, and costs plummet even further. $120 million USD per/km.

Approximate construction costs by era per km, in millions (2019 USD dollars)

Approximate construction costs per subway km, in millions (2019 dollars)

Download chart.

Era New York (mm USD 2019) London (mm USD 2019) Paris (mm USD 2019)
1900s 40 30 30
1910s 55
1930s 140 35 30
1960s-70s 700 150
1990s 1500 500 250

Full table.

Who said things got cheaper over time?

Costs to build subways have spiralled.

$40 million USD per km in New York in the 1990s. $1.5 billion USD per km in the 90’s.

While many of you, like me, might assume this is because of political factors or city density, you’re probably wrong.

The author of the presentation notes:

The cost difference seems to be mostly in stations.

To save money, he has uncovered the following cost items that best reduce construction costs:

  • Shallow cut-and-cover construction, disrupting the street for about 18 months. No mining except at undercrossings.
  • No mezzanines. All circulation, including fare barriers, should be on the platform level or at street level.
  • An island platform, ideally accessed from a street median, to avoid duplicating elevators, stairs, etc.
  • No signature architecture. Station designs should be reused systemwide. If art is desired, put on exhibits.

Rebuilding the London Underground in 2020

Est. Build Cost of London Underground Lines using 1990s costs (USD 2019)

Download chart.

Name Length (km) Cost at 1990s cost (mm USD 2019) Cost at 1990s cost (USD 2019)
Waterloo & City line 2.5 1250 $1,250,000,000
Victoria line 21 10500 $10,500,000,000
Bakerloo line 23.2 11600 $11,600,000,000
Hammersmith & City line 25.5 12750 $12,750,000,000
Circle line 27.2 13600 $13,600,000,000
Jubilee line 36.2 18100 $18,100,000,000
Northern line 58 29000 $29,000,000,000
District line 64 32000 $32,000,000,000
Metropolitan line 66.7 33350 $33,350,000,000
Piccadilly line 71 35500 $35,500,000,000
Central line 74 37000 $37,000,000,000
Total 469.3 234650 $234,650,000,000

Full table.

Assuming 1990’s London costs per/km of subway ($500mm p/km), even the 2.5 km Waterloo & City line would cost an estimated $1.25 billion to rebuild — maybe at that cost it would open on Sundays?

In total, it would cost an estimated $235 billion to build the London Underground today.

The London Underground carries about 1.4 billion passengers a year. If every journey cost a passenger $168 (about 12 times the cost of a travel card, which is already expensive!) the costs to build would pay for themselves in a year.

Built at Swiss prices ($120 million /km), it would be 75% cheaper at about $56 billion — a bargain… when compared to New York costs (@$1.5 billion per/km = $705 billion total).

Comparing to HS2 (UK)

HS2 vs London Underground construction costs per km

Download chart.

For those outside the UK, HS2 stands for high-speed 2, a planned high-speed rail network between London, the West Midlands, Manchester and Leeds.

It’s controversial, like many major infrastructure project, though the ยฃ307 million / $398 million USD per mile (ยฃ190.8 / $247.3 million /ย  per km) it is expected to cost (today) has been widely reported by the press.

Comparing this to the per kilometre cost of rebuilding the London Tube at 1990s prices ($500 million / km), HS2 doesn’t sound as expensive, though you don’t get as many tunnels for your $247.3 million!


I’ve taken aggregated prices from the presentation that have already been manipulated by the author. To get a better insight into build costs and where they were sources from would dramatically improve the quality of my reporting.


In total, it would cost an estimated $235 billion to build the London Underground today.ย 


  1. Data sources + data used in this post.
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