Tokyo Subway Construction Costs Deconstructed (PedestrianObservations)

Here is a list of Japanese subways and their construction costs, courtesy of Borners, who has been working on this as well as on a deep dive about London construction costs. I’d been looking for this data for years; someone in comments posted a link to a different sheet summarizing the same data years ago but I couldn’t find it.

Unfortunately, the list isn’t quite good enough to be used for all subway lines. The problem is that the numbers are given in nominal yen for the costs of constructing entire lines, including ones that opened in phases over many years during which inflation was significant. The table of lines and their construction costs in units of 100 million yen/km is as follows, with my best attempt at deflating to 2023 prices, still in units of 100 million yen/km; to convert to millions of dollars per km, the 2022 PPP rate is $1 = ¥94.93, so add 5.3% to all numbers in the penultimate column.

The confidence level is a combination of the length of time it took to build the line and the inflation rate over that period. The Oedo and Namboku Lines opened in stages over a decade, but during that decade Japan had no inflation, and as a result price level adjustments are easy. In contrast, inflation in the 1960s was high but the Hibiya and Tozai Lines were built quickly, so that the uncertainty based on picking a year to deflate to is maybe 10%. The in between lines – Mita, Chiyoda, Yurakucho, Hanzomon – all opened in stages over a long period of time with significant inflation. This makes it hard to use them to answer the question, what was Tokyo’s cost history?

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