Valentine's Day was this past weekend, a popular day for marriage proposals. In the fall of 2014, a man in the Netherlands attempted an ill-advised but very memorable proposal involving a mobile crane.
For reasons we may not ever know, a man wanted to be lifted in a personnel basket using a crane over a row of houses to propose marriage to his girlfriend. The crane he was suspended from overturned, falling into the house; and when cranes were brought in to recover it, the rigging slipped and dropped the boom into the roof again, causing further damage. Thankfully no one was hurt (although there was significant property damage), but we should learn from their crane-related mistakes:
- The crane was not properly set up.
a. The right rear (street side) outrigger was fully extended, but the front right was not and there didn’t seem to be a reason (the street was already blocked off).
b. The left front outrigger was fully extended, but the left rear was not because a parked car was in the way.
- They had two cranes on site that could be used to upright the crane that had tipped.
a. Two cranes should be used to upright a crane: one to raise the boom side and the other to lower the other side.
b. It wasn’t clear from the video whether they were using the second crane, because there appeared to be a hesitation in hoisting the boom. That allowed the sling to loosen and slide up the boom.
c. This problem is typical of trying to upright a crane using only one crane. When the crane being lifted goes over center it will attempt to upright itself quickly and its boom would jerk up.
d. When the sling slid up the boom, the crane started to tip again; shock loading the sling and breaking it.
- In the United States, OSHA would not be required to respond to this incident because
a. They were not using the crane and basket for work, so it is regulated by the states as "entertainment" like carnival rides or bungee jumping from a crane basket.
b. Even if OSHA had jurisdiction, they would not investigate this incident because there was only property damage and no serious injury or death.
(Story from Vertikal.net and Heavy Lift News)
