Update 2017/7/1: this is the most linked-to post of mine about construction costs, even though the dataset here is relatively small. You can see links to more posts, with more datapoints, on my static construction cost page. The long and the short of it is that in non-English-speaking developed countries, the typical range for urban subways is $100-300 million per km, with a few outliers in both directions.
This is a placeholder post, in which I’m just going to summarize the costs of projects in the US and the rest of the world. I will focus on subway tunnels, but also put some above-ground rail for comparison. No average is included – all I’m doing at this stage is eyeballing numbers. As far as possible, numbers are inflated or deflated from the midpoint of construction to 2010, and exclude rolling stock. The PPP exchange rate is €1 = $1.25, $1 = ¥100. For now, only dense infill subways are included.
East Side Access: $8.4 billion; excluding preexisting tunnels, this consists of 2 km of new tunnel in Manhattan and a new connection in Queens. So this is about $4 billion per km. Update 2011/6/21: the link here stopped working. Here‘s a slightly older link, saying the cost is $8.1 billion.
Second Avenue Subway Phase 1: $4.9-5.7 billion in 2007-17 for about 3 km of new tunnel. This is $1.7 billion per km.
7 Extension: $2.1 billion in 2007-12 for 1.6 km of new tunnel. Note that this has only one station, an unusually sparse spacing for a dense urban area. This is $1.3 billion per km.
Crossrail: £15 billion in 2008-18 for a line of more than 100 km, of which the primary component is 22 km of new tunnel under Central London and Heathrow Airport. Due to the extensiveness of the London Underground network, this is the most complex project on the list. The cost per unit of tunnel is about $1 billion per km, making this the only outside New York to cross the 1 billion line.
Central Subway: $1.58 billion in 2010-6 for 2.7 km of light rail tunnel. This project is only on this list because it has to cross under the double-decked subway (Muni and BART) under Market; the standards, including station size, are for light rail. This is about $500 million per km.
Jubilee Line Extension: £3.5 billion in 1993-9 for 15.9 km of route, of which about 80% is underground. The line went over budget by 66%, crosses under the entire London Underground network, and crosses under the Thames four times. This is about $450 million per km.
Amsterdam North-South Line: €3.1 billion in 2009 money for 9.5 km of new tunnel. The project has run over budget by a factor of more than two, leading to accusations of boondoggle and remarks that the project should not have been built. This is $410 million per km.
Toei Oedo Line: ¥1.4 trillion (Japan has no inflation, so year of construction does not matter) for 40.7 km of new tunnel. While the stations are normal subway stations, the subway tunnels are of smaller than normal diameter due to the use of linear induction technology. This is $350 million per km. A short subway extension of the Mita Line cost nearly $500 million per km, but the information about it is on a Toei factsheet that’s been scrubbed from the net.
Tokyo Metro Fukutoshin Line: ¥250 billion for 8.9 km of new track. This is $280 million per km. Tokyo Metro has claimed future lines will be $500 million per km as a reason to not build future extensions.
Berlin U55: €320 million for 1.8 km of tunnel in 1996-2009. While this line does not cross or connect to any older subway, it is in the center of the city, and thus qualifies as urban infill. This is $250 million per km.
Paris Metro Line 14: €1.13 billion in 1998-2003 for 9 km. This line crosses under the Seine and had construction problems due to catacombs. This is $230 million per km.
Circle MRT Line: S$10 billion for 35.7 km, to be opened in full next year. This includes a 50% cost overrun, and a substantial delay coming from a highway collapse in 2004 that killed four workers. Because the exchange rate, including PPP, has changed considerably in the last ten years, I’m not inflating, and instead using the present rate, making this the least certain conversion on the list. This is $220 million per km.
Copenhagen Circle Line: DKK21.3 billion in 2010 for 15.5 km. At today’s exchange rate, this is $4 billion and $260 million per km in exchange rate, but the Danish currency is severely overvalued, and in PPP (judging by the ratio of PPP to exchange rate GDP per capita) this is $170 million per km.
Durchmesserlinie: CHF1.82 billion in 2007-13 for 9.6 km of new commuter tunnel under the city, relieving the existing tunnel. This is $215 million per km in exchange rate, but the Swiss franc is severely overvalued, and the PPP value is only $136 million per km.
Barcelona L9/10: €6.5 billion in 2006-14 for 47.8 km. This line is fully automated and is nearly 100% underground, and has gone over budget by a factor of more than three. This is $170 million per km.
Naples Metro Line 6: €533 million in 2007-12 for 5 km of fully underground metro. This is $130 million per km.
Milan Metro Line 5: €500 million for 5.6 km of fully underground driverless metro. This is about $110 million per km.
Seoul AREX: 4.2 trillion won ($4.2 billion) for 61 km of line, about 60% underground, linking Seoul with Incheon Airport. This is a combined commuter and express line, and even all-stop trains only make 10 stations, by far the sparsest spacing on this list. This is about $110 million per km of tunnel – realistically a little less since the above-ground segments are greenfield.
Seoul in general gives its tunneling construction cost as $100 million per km in context of a proposal of an extension of the Sin Bundang Line that assumes a much lower budget, only $40 million/km.
Madrid gives the construction costs of its 1999-2003 expansion as €42 million/km, including rolling stock; translated to today’s dollars, this is $65 million per km. But those projects were not all infill and not all fully underground.
Observe from the low costs of Italian subways that corruption alone cannot explain high American and British costs. High Japanese costs can be explained by strong property rights protections and a process that favors NIMBYism; Paul Barter‘s thesis quotes sources arguing that the high costs of land acquisition in Japan are a reason why its cities never engaged in American-style urban renewal or massive freeway building.
Observe also that developing countries’ PPP costs aren’t very low: Beijing’s subway extensions cost about $150 million per km – see e.g. here and apply a PPP exchange rate of about $1 = 3.8RMB. The labor costs in developing countries are lower, but so is labor productivity.
Observe finally that Bent Flyvbjerg, known primarily for his work on megaproject construction cost overruns and strategic misrepresentation, wrote a paper on comparative US and European construction costs, which understated the conclusion that American costs are higher. The reason for his understating the conclusion is that the American projects examined are quite old, from the 1980s, and many have large above-ground parts.
Although the US projects included are only in New York and San Francisco, both high-cost cities, similarly high costs occur in other cities, just the projects are above ground. Portland’s light rail Milwaukie extension and Washington’s predominantly above ground Silver Line both have cost ranges of about $100-150 million per km, enough for a full subway in many European cities. Los Angeles’s Subway to the Sea is budgeted at $6 billion for the full Wilshire route to Santa Monica, i.e. $300 million per km; this is not really infill since it extends the subway out, but the neighborhoods served are quite dense, so it might qualify.
For some links of outward extensions abroad, see Brussels ($60 million/km) the future plans in Paris ($100-200 million, with one line at $50 million) and Seoul’s upgraded Gyeongchun Line ($33 million).