will connect the cities of Dalian and Yantai across the Bohai Sea, passing through two

deadly earthquake fault zones. At 76 miles long it will be longer than the current first

and second-ranked underwater tunnels combined, and at a cost of $42 billion, it will be extremely

expensive. But the Chinese calculate that it will be worth it.

For one, it will slash the eight hour drive between the two cities to under two hours.

It will also connect China’s isolated northern rustbelt with its wealthy east coast, adding

an additional $3.7 billion to the economy each year.

The experience could also establish the Chinese as the preeminent submarine diggers in the

world, and would be a serious practice run for far more ambitious potential future Mega-MEGA-projects

like connecting China to South Korea, or even Russia to the United States across the Bering

Strait--yes, that has actually been proposed.

This isn’t the first underwater tunnel project for Chinese engineers, either, who already

gained some experience by completing the 3.8 mile-long Jiaozhou Bay Tunnel in 2011. But

while the Bohai Sea is roughly the same depth as Jiaozhou Bay, the tunnel underneath it

will be 20 times longer.

When it comes to construction, if they’re lucky, the Chinese will encounter only soft

seabed, allowing them to use Tunnel-Boring Machines the whole way. But if they run into

harder rock, they’re going to have to use the “drill-and-blast” method embraced

by the Japanese during construction of the Seikhan Tunnel. Using tons of dynamite hundreds

of feet underwater is dangerous business, and it resulted in the unfortunate deaths

of four workers over the course of that project, and maaaany accidental leaks.

Reporter: “In 1976 the project hit its biggest crisis when 80 tons of seawater a minute began

leaking in. 1.5 km of tunnel flooded. It took five months to get back on track.”

Bryce: The Bohai Tunnel will also have to withstand magnitude 8.0 earthquakes. In 1976,

the deadliest earthquake in modern history -- a 7.8 -- killed a record 650,000 people

in Tangshan and surrounding areas. In 1969 a quake measuring 7.4 on the Richter scale

shook the Bohai Bay itself. And there doesn’t seem to be much the engineers can even do

about that threat besides simply reinforcing the strength of the tunnel walls. Of course,

they could simply not bore a long hole under a deep bay through two fault zones, but that

doesn’t really seem to be an option at this point.

Because officials throughout China are under enormous pressure to hit GDP economic growth

targets, and there aren’t many other options that could provide anywhere near as much economic

benefit as the Bohai Tunnel, which should break ground sometime in 2016.

For TDC, I’m Bryce Plank. Thanks for watching.