Towering upwards13 January 2021
Tower cranes are ubiquitous; every city seems to have several on its skyline. But getting them erected to do their tasks—and dismantling them afterwards—calls for the help of all terrain cranes. Julian Champkin finds that owners of each type of crane need to talk.
“Every story is a different ask,” says Brian Tierney, co-director of M & M Crane Hire of Slough, UK. Their all terrains are frequently called upon to help tower crane companies to erect their cranes. It is never routine.
A tower-crane can perform far higher lifts than an all terrain; but without an all terrain to set it up it cannot perform any lifts at all. Clearly we have here cranes in a relationship. The tower crane needs the all terrain; but what sort of all terrain does it need?
The answer depends on many factors. “First, you must find out what the tower crane customer wants,” says Tierney. “Assess his needs: what is the size of tower crane that is going up at the site? That will largely determine what size all terrain crane you will need to erect it.”
Michael Klein is product marketing manager for all terrain cranes at Tadano Demag. “The crucial considerations for an all terrain for tower crane lifts is a mix of reach and capacity,” he says.
“But also the required and available footprint for the crane comes into it. Very often, space is a premium on the jobsite, so you would want a system with the ability to position the outriggers independently from each other while still with the maximum possible lifting capacity.
“And higher capacities are always wanted. So, for example, our Demag AC 300-6 with 15t lifting capacity on fully telescoped 80m main boom is ideal for tower crane erection, as is our brand new AC 450-7 with 25t capacity on the same length boom.”
Alan Farmer is operations manager of Stoddart Crane Hire, based in the Scottish highlands. “As we speak, we have an all terrain erecting a tower crane for Falcon at Bairds Malt in Inverness,” he says. Bairds is a company that malts barley for whisky distilleries of the Highlands, so many, both in Scotland and elsewhere, might consider it a task of prime importance. “We are using a 250t Grove for the job,” said Farmer. “It is a tall tower crane and this is a two day operation.
“It is about capacity and height. You put the column of the tower crane up first, of course, then the top platform; so you need to be sure that you have enough height on your all terrain for that. Logistics is a big part of it.”
Charlie Evans of UK mobile crane hire company Southern Cranes & Access has been lifting tower cranes for 35 years. “Ask the weight and the radius of the tower crane—that determines the size of the machine you will send,” he says. “Generally it will be an 80t all terrain or upwards. Occasionally a 60t capacity one might do the job, but 130t is the most popular.
We have Liebherr and Groves in the fleet. The Liebherr LTM 1130 is popular for tower erecting, and Southern Cranes have just bought a Grove GMK5250XL-1 with the extra-long boom. It’s the first in the UK, and another useful tool for tower lifts.
“You get to know the weights of the tower crane components for the differing crane manufactures. Once you know the radius that you must lift to, you send the most cost effective crane size that can do the job whilst maintaining an acceptable margin for safety.
That is because you want to give the customer value for money. Of course there may be other factors involved, such as access—you will want to be sure that you can get your crane to the site—or being near a Network Rail installation for example which imposes more restraints.
“And certainly the variable outrigger systems like VarioBase and Maxibase and VarioBallast are great advancements in crane technologies that are very useful in the planning of some jobs with access challenges.”
Bob Jones is with City Lifting, who have both all terrains and tower cranes in their fleet. “Every job is different,” he confirms, echoing Tierney at the start. “You might need a 400t all terrain, or a 100t machine might well be big enough. It depends on things like the radius of lift and how close you can get to the tower crane base, as well as the size and weight and dimensions of the tower components.”
With which Tierney agrees: “The tower crane owner will tell you what each component of the crane weighs,” he says. “So you can work out the furthest lift at the highest load that you will have to perform. A tower crane can call for a 50t all terrain or a 1,000t all terrain to erect it. It depends on access, on the size of tower crane, how close your crane can get to the base of the tower: a dozen factors go into that decision.”
Beginning Vs End
Those discussions happen at the pre-planning stage of the lift. “But at that pre-planning also you have to consider a harder problem: How you are going to take the crane down afterwards. That will be more difficult,” says Tierney. “The access laydown spaces that you had before construction are likely to be filled up with the newly-built structures. The tower crane might even be in the middle of the nearfinished construction, surrounded by the new building on all sides.
So you might well need longer reach or greater height on your all terrain to lift it out. The available footprint at the start is going to be very different from the footprint at the end. The lesson is: ‘At the first assessment of the job don’t just think about the beginning; think about the ending too.’”
Evans of Southern Cranes & Access makes the same point: “It can certainly happen that getting it down becomes a real problem. We have never left one behind yet, but if you don’t have a conversation with the tower crane owner at the beginning about getting it out at the end, you may have some difficult conversations with him six months later.”
And, from City Lifting’s Bob Jones: “For erection you may have a flat empty site because the crane is about the first thing to be installed. That can be quite different at the end of the project.” M and M’s Tierney gives a reallife, and current, example: “We have just erected a tower crane that is building a care home. Care homes are long and narrow rather than multi-storey, so they are putting 60m of boom on the tower crane to carry 2t at end of the boom—a tub of mortar, a pallet of bricks, and so on. We sent a 100t machine to put the tower crane up. But the tower is set in the middle of the building that is going up around it, so we shall need a 130t machine to take it down.
“It is natural on the part of the project owner to remove the tower crane as soon as possible. When the brickwork is done the care home people will want to lay out the pathways around it, do the garden planting; but of course we need those areas, for laydown space, for our all terrain and its outriggers, for the trucks to transport the crane segments.
So that’s why you have to talk to everyone involved, not just the tower crane owners. There is a lot of site visiting: perhaps two or three visits ahead of removing the crane. We will say to the care home people ‘Please don’t do your gardening yet!’ It’s not a message they want to hear, so you have to point out that if they do plant out they will only have to replant after we have been.
“Finding that laydown space at the end of the job is not easy: 60m of boom takes up a fair bit of room. Here of course is where the pre-planning helps. You can say ‘This is the area I will need to remove the crane’.”
Manitowoc, manufacturers of Grove all terrain cranes, of course are the manufacturers of Potain tower cranes; not surprisingly, they say that there is a synergy between the two. In early 2020 Manitowoc’s Didier Forest developed a new program for top-slewing tower crane erection. In an on-line guide he lists his ten steps to getting it right.
Coordinating the logistics is vital, he says. “Many city centres have limits on when roads can be closed, or heavy vehicles can drive downtown, and each truck might require its own permit with fees for diverting the road to traffic.
Both the tower and the mobile crane need to arrive on site at the right time in the smallest available convoy sizes to avoid waste and waiting. The erection team and the customer must prepare the transport sequence and installation in advance.”
Tierney confirms that need for planning: “There is a fair bit to it, and planning and talking is everything—talking to the site owner as well as to the tower crane company. Timing is important too: the tower crane guys will have laid their concrete base slab, but you have to wait for it to cure—you cannot put the crane onto green concrete. Then as soon as it is cured they will want to be at work, so precise availability of your all terrain can be an issue.”
“We have tower cranes from Comansa and others, and Liebherr and Demag all terrains which we can use for erecting them,” says Jones of City Lifting. Having both types in the same fleet does not necessarily mean instant availability: “Liaison is still a big part of it. We still have to book the erection cranes.”
Tierney again: “Typically the tower crane company will tell us what they want, and what they have worked out for the lift. We confirm their assessment, or we amend it as necessary, or we make suggestions as to the all terrain that will do the job best. We can say ‘Yes, that particular all terrain could do the job, but we have this new model that has longer reach and could do it from that different position instead, which might be better.’”
Once on-site, do as much as you can on the ground, says Evans: “The slew ring is generally the heaviest component; it can weigh anything from 7t to 13t. That has to be lifted to directly above the centre of the tower crane’s position. That will be the radius of lift that defines the job.
“The front jib sling points vary depending on jib length and mean that you lift it to a lesser radius than that, in most instances, to a position between the tower and your all terrain assuming you have your all terrain positioned right. But when you are lifting the jib, try to plan it so that you have a laydown area for it on the ground and assemble it there, then lift it as a single unit, even if it is 85m long.
“You do that to limit the number of higher risk activities in the air. With the flat top variants you can lift it in sections and assemble them in the air, of course, but that introduces additional activities in the air for the guys working high up, with all the potential hazards that involves. So do all the building you can on the floor. Sometimes you will not have room, but that is what you do if you can.”
Even a one-piece jib lift calls for a steady hand from the all terrain operator: “The gangs in the air find it really helpful if they know the crane driver,” says Evans.
“You need the crane movements to be smooth and precise. Here you have people anywhere up to 100m up trying to grab and get hold of the jib that you have dangling from the end of your crane. You are trying to deliver it literally into their hands, and you probably cannot see it and are being guided by radio by someone else. So you take no risks: no jerky movements, no surprises for anyone. It takes time. It’s not a job to be rushed.
It depends on preparation beforehand and on the guy on the levers knowing absolutely what he is doing. It is not a job for a rookie first-day-on-thejob all terrain guy. Let him get his experience on simpler jobs; leave this one to the experienced operators.”
It makes, say all our experts, for close relationships between the tower crane group and the all terrain operator: “Obviously we work closely with the tower crane people,” says M & M’s Tierney. “It is a niche market, and relationships develop. They have their favourite all terrain operators— not just their favourite companies but their favourite crane operator within that company. If the operator moves companies, they will follow. They know that there are crane drivers, who can move the levers all right, and crane operators, who have a real feel and knowledge for their crane and what it can do, and that there is a big difference between the two. Tower crane erectors are a unique bunch.”