June 30, 2016 7:59 AM EDT

Last July, high-voltage cables running through two 106-year-old rail tunnels under the Hudson River failed, choking train traffic from Boston to Washington, D.C., for four days. The entire Northeast depends on this very corroded artery. Luckily, the prudent course–investing at least $15 billion to build two new tunnels and make other infrastructure updates–has finally gained steam.

Meanwhile, if one or both of the existing tubes needs a shutdown, “it’s an existential threat to the economy of New York, the Northeast and by extension the whole country,” says Tom Wright, president of the Regional Plan Association think tank. So start digging.

Write to Sean Gregory at sean.gregory@time.com.

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