Why did the ship hit the bridge? Math error

A ship carrying deck sections for the new Tacoma Narrows bridge hit the old bridge last week because engineers miscalculated the height of the underside of the old bridge, the state’s project manager says.

The ship had 16 deck sections stacked 135 feet above the water level. The bridge builders thought it would glide under the sidespan of the old bridge with 36 feet to spare. But temporary scaffolding on top of the deck sections hit the underside of the bridge and toppled over on Friday.