During the construction of Interstate 40 in California, the Santa Fe Railway Company wanted to find a way to cut through the Bristol Mountains, as this would prevent the highway from having to swerve around them like the Santa Fe Railway and Route 66 did. That would, however, involve cutting through 4,000 feet of rock, which would've necessitated either a huge tunnel or 500-foot-deep cuts in the mountains, costing around $22 million . Far too expensive for the company.
This attracted the attention of the Atomic Energy Commission, who offered their own plan, called Project Carryall. This would've involved the use of 23 nuclear weapons, 22 to hollow out the path and the 1 for the runoff water, excavating a total of 68,000,000 cubic yards of land. All of this would cost only $13.8 million.
Of course, as with all of Operation Plowshare's proposals, none of them panned out. Carryall was scrapped in 1968 and Interstate 40 was instead carved out using conventional means.