Last week, the ramps, each one about 1,500 feet long, were wired with a total of 944 bits of ordnance called line charges. The ground beneath them was piled with shock-absorbing sand.

On Sunday morning at the official viewing area on the Brooklyn side in Greenpoint, half a mile from the bridge, Gov. Andrew M. Cuomo recalled riding to visit his grandparents as his father, the former governor Mario M. Cuomo, drove like a crazy man to beat the traffic. “But it was impossible to get to the Kosciuszko before there was traffic.”

A couple of hundred civilians got to watch from the viewing area, too. “It’s kind of a once-in-a-lifetime opportunity,” said Joan Mulry, a retired New York City teacher from Long Island who crossed the bridge every school day for 23 years. “When are you going to see a bridge implosion?” She reflected on the untold hours she had spent stalled in 6 a.m. traffic at the top of the world. “Not too pleasant.”

Samantha Chtcherbinin-Reynoso, an 11-year-old who lives in Jackson Heights, Queens, and goes to school in Manhattan, recalled looking down and wondering if there were sharks in Newtown Creek.