Tower crane with a cabin on ground level

Question

Pardon me for kind of a stupid question, but I keep wondering. Traditionally, tower cranes' cabins are located at the top of the tower. I can understand why it have been necessary up to ~1990s, when it was the only way for a human to get reliable real-time visuals of what's going on. But today, with the advent of camera and monitor technologies (when cameras and LCD monitors are dirt-cheap), what is the exact problem with moving the crane operator's cabin to the ground level and make all visuals using a system of cameras?

Searching the Internet for the answer, I've encountered quite a few of companies that produce camera systems for cranes, but it looks like that majority of them propose to use cameras as additional viewing aids (i.e. "view from the hook", "view from the pulley", etc), but not replacing the sky cabin.

From kind of delitant point of view, having a cabin up high actually poses a bunch of problems, i.e.:

• safety: fallen crane = very real chance of death or major injuries
• comfort: it's very hard to maintain proper air conditioning and temperatures up high
• time consumption: a way up to the work place takes 20 minutes for an operator, and takes lots of physical endurance to do so

Is it really feasible in modern world to continue using sky cabins on the tower cranes? Am I missing something obvious, or is it just very persistent tradition that nobody dares to break?

Answer 1

The crane operator at the top of the tower doesn't just have a view of the load being lifted. He/she can see the entire surrounding area and take account of any potential hazardous situations that might develop, for example other workers moving about who are not aware of what the crane is intending to do, vehicles being driven into potentially dangerous positions, etc.

In fact, the crane operator being able to see the actual load isn't necessary at all. Cranes are often driven by someone who can't see the load, by watching hand signals given by someone who can see it - and sometimes there may be a chain of two or three people signalling to each other to get a line of sight from the load to the crane driver.

A friend of mine was on the "receiving end" of a fairly extreme one-off example of that sort of operation. He wanted an expensive ($100,000) full size grand piano moving into a room on the second floor of his house, but there was no way to get it up the stairs. The solution was to use a mobile crane parked on the road, lifting the piano across the garden and over the roof of the house, and lowering it onto a second-floor balcony on the "blind side". The crane operators didn't think there was anything difficult or unusual about that operation - especially when they discovered that the legs could be removed from the piano (moving pianos was not their usual line of business!) making it much easier to handle than they thought it would be.

Of course you could argue that a global view could be provided by an array of cameras and a bank of monitors - but two eyes and one brain are a cheaper and more reliable solution.

Answer 2

It is not trivial to replace human vision with a camera in this sort of situation.

• it is difficult to reproduce good depth perception with cameras
• the human eye can change focus quickly and intuitively, in order to scan between near and distant objects you would need to be constantly refocusing the camera and potentially missing information out of the current depth of field this is one reason why cameras aren't a good replacement for rear view mirrors).
• humans have an innate sense of orientation and where they are looking in space. Trying to reproduce a wide field of view with multiple remote cameras can be very disorientating.

This isn't so much ab out the load itself and its path from its start point to end point but overall situational awareness and being able to pick up emerging hazards.

These sorts of systems are just about possible, the F35 warplane uses a panoramic camera system with a VR helmet display but is is extremely expensive to implement and has had a lot of problems.

To address your particular points.

• if a crane falls down this is very bad, whether or not someone is in the cab, as a result it should be very rare so having an operator in the cab is not a major safety concern.
• cranes need power anyway so laying on heating and air conditioning is not, in itself a big problem. Besides the people working on the ground on the rest of the site will be out in the weather anyway, that's just a fact of the construction industry.
• many construction jobs are physically demanding, but for a crane operator climbing up to the cab may be the only exertion they do all day. If its a real problem you can just fit an elevator to the crane.

So the short answer is that it would be technically very difficult to adequately replace a crane operator with a remote system and there is no compelling reason to do so. The main reason for putting the operator up there in the first place is that they have a very good field of view, which is difficult to reproduce with cameras.

Answer 3

From 1924 to 1932 Sydney Harbour Bridge was constructed. It used two creeper cranes on both sides of the arch during construction to hoist people & materials.

The crane operators couldn't see what they were hoisting, "they were given orders by telephone from officials working some 400 ft below". One of the pictures in the above link shows inside the control cabin of one of the cranes.

Had current camera technology existed when the bridge was being constructed, they most likely would have used it.

Enabling crane drivers to directly see what is being hoisted is ideal, but not necessary, provided correct safety measures are used. It all comes down to safety and risk mitigation.