Cranes, drones and giant fans
Bill Price / director / WSP
Losing time due to wind is often about not being able to use a crane. It seems to me there are two issues: the safety of the operator as the crane moves in the wind, and the load on the end of the crane swinging about.
So I started thinking about stopping the crane from moving. On our Goldman Sachs HQ site in London, there are four cranes. Could there be a way of linking them together to stabilize them in high winds? In other words, using the cranes as a kind of triangulated grid. Then you could install a net or platform, or a very lightweight membrane above the jib to provide some protection from the rain.
A beam crane is a similar idea. We always tend to think of cranes as tall masts with a jib that swings around. But to build a ship or a nuclear power station, you build a giant crane and run a beam across the top to lift things. You wouldn’t do it for a high-rise building, but it would work for a more modest out-of-town residential block or business park. Then you can do everything from a much more stable platform.
When we stabilize super-tall buildings, we use tuned mass dampers, so when they try to sway in the wind, there is a passive or active device — a weight or a tank of water — that counteracts the movement. Could we invent a tuned mass damper for the crane?
Taking a more active approach, you could use large jet fans to counteract the wind. With today’s technology, it would be possible to work out exactly where the crane should be, and then the fans and other devices could work together to keep the crane in the same spot. At the moment you might have to stop using the crane when the wind reaches 20-30m/s, but you could push that up to 40-45m/s by actively managing and counteracting the effects. Or you could over-specify the cranes — for example, using cranes that are designed for very windy places like Scotland or the North Sea. Of course, you would still need to manage the load. It might be much more efficient to use tethered drones to pull the load into the right spot. The crane would still take most of the weight, but drone technology could compensate for the swinging. A bucket of concrete might be a bit heavy, but it might work with a piece of cladding or something else with less mass. Cameras have something called “lens stabilization”, which senses the movement of your shaky hand and makes micro adjustments to counteract it. Could we not scale that up?
Rain is trickier. It would take a massive amount of energy to vaporize it — if you consider that lightning is really just droplets of rain rubbing against each other, you can see the energy involved. Warehouses use what’s called an “air curtain”, which can be so powerful that a bird can’t fly through it. If there was a piece of kit that couldn’t get wet, could we blow air over it very fast so that the rain couldn’t land? That would be very expensive, but you might only switch it on occasionally — it’s not raining all the time.
Theoretically, it might be possible to charge up the rain particles electrically and then use a giant magnet to pull them out of the way. But the infrastructure to do that might cost more than the building itself. And then there’s the effect on all the metal and electrical objects in the vicinity. Credit cards would cease to work, the bricklayers’ trowels would be sucked onto the magnet, and their lighters would all fly through the air …