Infrastructure Projects - Construction Technology
A Practical Guide to Construction Techniques and Practice
There is an arm here. It's a little hard to make out these details. I believe what happens is this section is attached to this arm, this outstanding arm. Then the arm slides back in, drawing the tower section with it. In other words, the hook can only pick this piece up and bring it close to the crane. It can't get any closer. Now you need to kind of an outrigger to come out, grab onto the piece and slide it horizontally in place. I'm not sure you can make it out on your screen, but there is an ironworker here guiding the bottom of the tower to make sure it comes into this space cleanly.
Here's another photo, different crane different location and this crane to begin with. If we look at the crane for a minute, this has a luffing boom. It does not have that horizontal boom. This is a higher capacity crane. You can see this extension in place, and the crane is lifting a section of the tower. It's going to attach to that extension. By means of that extension, it will be drawn inside the open space.
I happened to be walking by this building while this process was taking place. You rarely see this happen, because the crane jumps on the weekend when it's out of service and not required for construction. That's when they usually make the jump. So I'm never around for that, but this happened to take place during the week. I happened to be there with a camera, with a video camera, and I got the video camera out of my bag, just in time to make a very shaky video, which I'm going to show you. I apologize. There was no time to get the camera up on a tripod and do it carefully, but you will get to see a minute or so of this activity.
I've explained to you how the upper part of the crane is wider than the tower. It telescopes over the tower, and it can ride up. Then when you're completed your construction, it can ride down. Having said all that, why isn't that evident in this photo? Why isn't the top section wider than the rest of the tower? Well, this, this crane does not climb. This crane has been assembled by another crane. Another crane has lifted it up there and lift it up the other pieces and assembled it in place. That's as high as this crane will ever go. You will pass many tower cranes that have this kind of a look. They are not climbing cranes at all. They've been assembled when the construction project is over. This big crane will come back again and disassemble them. Here's this very shaky video.