in 1968 channel 2 reporter charlton cordell told us about the b.a.r.t. tunnel. during the times, one of america's longest. reputed the only project ever to lose money. in san francisco water and mud 100 feet underneath the financial district made these one of the most difficult tunnels projects in history. described as the biggest story of engineering talent ever assembled, the crown was this, a tube under the bay. they built 57 binocular shaped sections each weighing 10 now tons and launched them like ships at the bethlehem yards. >> the first tube i will never forget it, sunk. >> reporter: someone left the hatches open on that first tube, it went straight to the bottom. >> it cost them $1 million to raise that tube. that was something. >> reporter: more careful after that the contractors used special barges to position the floating tubes in the bay. engineers sunk them with .1 of an inch precision. once the sections were joined under water, channel 2's cameras went down for a tour. >> it's designed to withstand with an earthquake with the magnitude of the 1902