Watching the awful tragedy caused by the earthquakes in Turkey, and in general, the biggest problem is obviously removing the rubble to rescue people, why do they not install a crane (2+ days) and use mobile ones in the meantime?
Cranes are great for moving large quantities of material quickly. But they are not very accurate and lots of stuff gets dropped. They are also very heavy and not at all gentle.
Imagine using a JCB to empty a ceramic flower pot whilst trying to keep your flower alive.
Imagine a big bowl full of M&Ms. You must grab a handful without looking at the bowl, this handful must have exactly two green ones. If it has any more or any less than two, someone dies.
That’s why. Cranes are not precise. Someone burried among the rubble can be injured by the crane itself, by the shifting of the rubble, etc.
You generally need a large flat stable surface to put a crane on these are not generally available where they would be needed and the area is likely to be prone to aftershocks which makes operating a crane exceedingly dangerous not only for the operator, but anyone underneath it.
Firstly there is not enough cranes in Turkey to cover all the affected areas. And secondly the rubble is all laying on top of each other and leaning on each other so you can not remove one piece of rubble without causing another to fall over. Typically the pockets where people survive is caused by two pieces of rubble leaning against each other, similar to how two sides of a roof leans on each other to create the living spaces of a house. If you remove of of the pieces of rubble there is nothing supporting the other piece and it will fall over and crush the people trapped under it. Obviously as time becomes more critical the rescue workers will start using more and more heavy equipment. The workers eventually have to chose between crushing some people who survived the earthquake or letting them die from the elements. But as far as possible they will search thrugh the rubble by hand and using dogs before they bring inn the heavy equipment to clear it out, and then start again once a few pieces have been removed. And when people are located they use as little equipment as possible to extract them in fear of collapsing the rubble on top of them, often having engineers conduct a full survey of the heap of rubble to figure out what they can and can’t do.
Logistics, most cranes have to either be trucked in or moved using their own power. Very few have anything but tires on them. It is much easier to maneuver an excavator over destroyed roads and fallen debris than it is a crane. Plus you have to think about weight rating, rubble often has the be cut up to be moved by crane, most building cranes only hoist up tiny parts of a building at a time and rarely (if ever) move large sections.
Lastly, cranes are much more rare than excavators. I know several people who personally own varying sizes of excavator. I only know two people with cranes