Yesterday's crane collapse on the Tappan Zee Bridge snarled traffic for hours and left four people with minor injuries, but the crane didn't hit any of the many cars on the bridge and no one was killed, which Governor Cuomo said yesterday is "nothing short of a miracle." An investigation is now underway to determine the exact cause of the collapse.

The collapse occurred at about noon yesterday, and for nearly two hours, traffic on the bridge was at a total standstill. The crane was one of 28 installing pilings for the new Tappan Zee Bridge, a $3.9 billion project that Cuomo touted yesterday as the "largest infrastructure project in the United States of America." Construction on the bridge began in 2013, and though it has seen its share of terrifyingly large cranes, no bridge workers have died or sustained serious injuries so far. The new bridge, which is being built just north of the existing structure, is projected to be completed by 2018.

In March, a tugboat collided with a construction barge near the construction of new bridge, and three of the tugboat's crew members died.

The lack of serious injuries in yesterday's accident, Cuomo said, was "very, very lucky," as the collapse easily "could have been a really, really terrible tragedy." One lane of the bridge sustained what the governor called "significant but not extensive" damage, and he said that "when you see the actual crane and the damage and the damage to the roadway, it really is nothing short of a miracle that nobody was hurt" seriously or killed.

Three people were injured yesterday when two cars crashed while attempting to avoid the collapsing crane, and one bridge worker also sustained minor injuries. The crane operator was not injured.

Past bridge-building projects in this city have been deadly: as the New York Times notes, more than 20 people died during the construction of the Brooklyn Bridge in the late 19th century; three people lost their lives while raising the Verrazano-Narrows Bridge in the 1960s; and one worker died during the construction of the existing Tappan Zee Bridge in the 1950s. The existing bridge was built to last just 50 years, and is traversed by nearly 140,000 vehicles each weekday.

"It's a miracle that the boom fell across six lanes of traffic, cars that are doing 60 to 70 miles an hour, and not one car was hit by the boom," the business manager of the union that represents crane operators told the Times. The boom was apparently 256 feet long.

The investigation into what caused the crane's collapse is now underway, and investigators have already ruled out weather as a factor, according to ABC—winds were blowing at about 16 miles per hour at the time of the crash, compared to the 25 mph gusts at the time of February's fatal crane collapse in Lower Manhattan.

"It was either a problem with the crane, problem with the hammer or its operator," said Terry Towle, president of Tappan Zee Constructors, during a press briefing yesterday.

But Thomas Barth, a crane operator safety expert who frequently conducts investigations into crane accidents, but isn't investigating this particular one, told ABC that "it's not the crane's fault, it is human error." The crane was apparently equipped with a computer that was supposed to tell the operator if he was carrying too great a load, to reduce the likelihood of overload accidents.

As of this morning, six of the bridge's seven lanes were open—the southernmost lane sustained notable damage in the crane collapse, and could remain closed for days, Cuomo said yesterday. Officials are still urging commuters to take alternate routes, as they expect there to be some delays on the bridge.