Did the crew working on the crane that collapsed in New York City Feb. 5 act soon enough and have enough time to secure the equipment before strong winds blew?

In response to last week’s crawler crane collapse in lower Manhattan that killed a pedestrian, New York City Mayor Bill de Blasio announced new safety regulations Feb. 8 lowering the maximum wind speed at which the cranes must stop operating, to a sustained 20 mph or gusts of 30 mph. Previously, crane operation could continue until steady wind speeds hit 30 mph or gusts reached 40 mph.

侧重于风，一位起重机专家建议，在风很麻烦时确保起重机可以打开更多麻烦的大门。

另一位专家建议，起重机操作员可以轻松地犯错，同时将起重机臂和繁荣降低，适当平衡，以一种称为千斤顶的操纵。

"The main boom was not at the correct angle," speculated one crane expert after reviewing a video of the accident. "The main boom was too low to jack-knife."

"It's simple, but complex, a tricky procedure with that amount of boom," the expert claims. "Why was this not done the night before?"

As part of its crane safety procedures, New York City's Dept. of Buildings sends out emails to crane operators about potentially troublesome weather the following day. It isn't clear what if any information the city provided the crane operators.

Tricky Transitions in Securing Crane

另一位远离纽约市的专家证实，一旦风速降低了起重机的困难。

Aviad Shapira, professor of construction engineering and management at the Technion—Israel Institute of Technology in Haifa , says securing a crane under windy conditions may provoke trouble during the transition.

在那个时间the collapse early Feb. 5,起重机的操作员由于大风而降低了565英尺长的繁荣和臂臂。随着繁荣和吉布的下降，他们似乎迅速升高，直到他们撞到了沃思街的建筑物和汽车，这是一条狭窄，不拥挤的小街。

The falling boom struck David Wichs, 38, as he walked down the street, killing him instantly. Three others were injured, two seriously. Thomas O’Brien, 73, suffered a head injury as the crash trapped him in his car, while Dawn Kojima, 45, was struck in the head by falling debris on her way to work.

The crane was working on the renovation of 60 Hudson St. Galasso Rigging and Trucking, a New York City-based company with more than 60 years of experience, ran the crane.

Another longtime New York City-area company, Bay Crane, owned the equipment and employed operating engineers' union member Kevin Reilly, 56, as the operator. He apparently was uninjured.

理论比比皆是

所有起重机都必须使用within the manufacturer's or designer's rated loads用于使用条件。

事故发生后不久，一些人建议在降低臂和繁荣导致悲剧时制动故障或不当序列。起重机头痛球的照片（这是起重机钩子的一部分）的照片，该球显然坠入了现场附近的办公室，引发了更多的猜测。

起重机专家说，尽管风速是一个因素，但几个因素可能导致事故：天气，包括风，人为错误，管理错误或技术故障。

Shapira said a key is whether due precautions were taken during the snow and wind conditions.

“The question is, have due precautions been taken? If not, it is a typical management issue, combined with an environmental factor," he said. "If the snow was wet, it added significantly to the weight of the boom." He speculates also whether the issue of the extra weight was ignored, which could be "another management issue.”

Wind speed is greater the higher you go above grade, notes Bradley Closson, president at CRAFT Forensic Services. “This was a tall boom so the wind at the tip was probably more than what has been reported. Additionally, "buildings create a 'venturi effect' so that the wind funneling between the buildings can be much faster than that felt before entering that funnel,” he says.

The Feb. 5 accident occurred on the second attempt to secure the crane, after the first had been halted following gusts as high as 40 mph.

But lowering a crane boom and jib in high winds could bring on other possible problems.

“What might look as a necessary action to be taken in the face of the severe storm, namely, lowering the boom, could actually – under certain circumstances – work the other way around, worsening the situation,” says Shapira.

“起重机设计为在他们的“自然”state" of lifting and moving loads," says Shapira. "When you set up a crane or take it down, you put the crane in an 'unnatural' state. If during that time other factors surface such as wind and accumulating wet snow, the crane might be in jeopardy and the situation more hazardous."

The crane expert adds that in this case the crane was being secured under harsh conditions, "which also gives room [for] plenty of human errors.”

CORRECTION (2/10/16 11:16 A.M.): An earlier version of this story mentioned Gilbane Building Co. in error. Gilbane has no involvement in current 60 Hudson Street work. Project owner DataGryd announced last October that Nova Mission Critical is executing the buildout of the current phase of its 240,000-square-foot urban data center. A spokesman for that firm confirms it is working on site and that the accident is under investigation.