$250mm per km in paris and berlin. $145mm per km in Sao Paolo. $130mm per km in singapore. $58mm per km in madrid. https://www.citylab.com/transportation/201

$250mm per km in paris and berlin. $145mm per km in Sao Paolo. $130mm per km in singapore. $58mm per km in madrid. https://www.citylab.com/transportation/2011/11/1-billion-doesnt-buy-much-transit-infrastructure-anymore/456/ https://www.citylab.com/transportation/2011/11/1-billion-doe... $55mm per mile ($34mm per km) would be pretty cheap, but closer to what the rest of the world pays for subways than what NYC does. accounting for musk-math, expect it to cost more like $70mm per km, which would put it on the low end but not the bottom of international subway construction costs.