Tangentially, what's impressive about Shanghai's metro is how quickly it became the longest. It essentially went from nothing to the longest in 15 years. Compa

Tangentially, what's impressive about Shanghai's metro is how quickly it became the longest. It essentially went from nothing to the longest in 15 years. Compared to the 20 years it took the Big Dig, or my own home city which has been talking / debating / purchasing / cancelling / assessing / suing re mass-transit, it really is an impressive achievement.