There's always
a 3'9" gap.

When Boston undertook the Big Dig to bury its elevated Central Artery, the project also carried I-90 beneath Boston Harbor through the Ted Williams Tunnel. Its underwater section was assembled from twelve enormous steel tubes, prefabricated in Baltimore, towed to Boston and lowered into a trench on the harbour floor.

When the final section was lowered into place, the alignment came up three feet nine inches short of the South Boston connection. Engineers made up the difference by extending the land-side tunnel to meet it.

I saw the story in an episode of Megastructures while trying to think of a company name in 2010, and I couldn't get it out of my head. A gap nobody planned for, in a project run by experts with a huge budget, swiftly handled by engineers who just got on with it. The name chose itself.