Zhenya & Ebbie -

Crane accidents aren't really much more common than other kinds of construction events, but when one comes down there's usually little warning and it's very difficult to get clear after the fact. As with any construction site operations, there are a lot of hazards for the workers that must be managed, but the sheer length of the cranes means that they can come down quite a long distance from the site. The likelihood of injury at any specific place in the "fall zone" is small, but it's a big zone.

Casual gawkers not only expose themselves to at least some risk any time they're in or near heavy construction work, especially if they ignore what's going on and don't recognize what's risky; but they also can distract and/or impede workers who are at much greater risk and must pay attention to what they - and everyone else working there - are doing.

You can easily search "crane accidents" to get an idea of how much actual risk is likely. The hazard is not usually limited to things that "fall on the buildings." Since a purpose of most such cranes is to move things onto and off of the building, they nearly always must have a reach that extends beyond the building, and they never "fall straight down." The primary hazard area can be estimated approximately from the height of the crane plus it's "reach" and anything in that zone can be hit by whatever falls.

Chicago and New York, within the past couple of years, have had widely published reports of a half dozen or so tower crane collapses that injured people on the streets below and in a couple of cases "crushed" adjacent buildings.

Crane designs and construction are generally "safe," but with some types the crane must rely on the integrity of the building it's working on and inspection and certification of the structures is frequently left to "municipal code inspection" or omitted altogether.

Erection of the cranes is a very technical job and strict licensing requirements for those who manage it are in place almost everywhere - but "shortcuts" that compromised safety are revealed in nearly every accident investigation.

The "capacity" of a given crane changes over time and most codes specify frequent recalculation of how much it's safe to lift, based on things like cable wear but often omitting allowance for the wear on the pulleys that the cable runs through - and frequent cases are found where the one responsible just "wrote down the result" that he was "pretty sure" would be there, or that was "what it had to be to get the job done."

If you're really concerned a couple of starting points:


Sample 1

Random Photos (including lots of small lifters)

tracking site ( I think there's an archive here.)

One in NYC 2008

Design News Article

For the construction workers, the most common risk is getting fired if (when?) you screw up the numbers or don't do them all. (The numbers aren't really all that simple, although they're "standardized.")

John