The streets of London are generally narrow and buildings of all ages are nestled tightly together. There is not a lot of space in the city centre. This is why the crane of choice is predominantly the tower crane. Unusually, however, there is one large project that has chosen to use crawlers instead.
New Street Square is a massive office and retail development by property company Land Securities just off Fetter Lane, midway between the shopping and theatre district of the West End and the financial district of the City.
Four buildings ranging from five to 17 storeys high will provide 700,000 sq ft of office space and 30,000 sq ft of retail space.
First, however, seven ugly, old, life-expired office blocks are being pulled down to make way for the new development. The demolition contractor, Cantillon, started on site in September 2004 with an asbestos removal programme, and began demolition proper in January. By the beginning of July it had pulled down five of the buildings, and had handed half of the site over to main contractor Sir Robert McAlpine for piling to start.
For the first four buildings, Cantillon used a 90t class Hitachi Sumitomo SCX 900-2 crawler with a 48m lattice main boom and 15m of fly jib.
Unusually, there was room to set up and manoeuvre this machine because the site straddles a side street that has been closed off for the duration of the project. The first five buildings to be demolished were all 12 storeys high. It was reach that the contractor required rather than lifting capacity. The heaviest loads on the job are mini-excavators weighing 9t. These are fitted with nibblers, and are worked from on top of the building.
From ground level, a 65t Hitachi long reach excavator also nibbles away at the structures. The crane also takes out sections of beams and walls for breaking up on the ground. The amount of material being moved out is equivalent to 2,500 truck loads. The third role of the crane is transporting personnel vertically in purpose-designed cages.
For the sixth building to be demolished, which was 17 storeys, the reach of the 90 tonner was not quite enough. Therefore, from the beginning of May it was joined for two months by a Hitachi Sumitomo SCX 1000, a 100t class crawler, fitted with 50m of main boom and 44m of luffing jib. This was used to help reduce the highest building down to 12 storeys high, from which point the 90 tonner had the reach to take over and the 100 tonner left the site.
Both cranes were hired from Hitachi Sumitomo distributor NRC. “We’ve worked with them before,” says Cantillon commercial director Jim O’Sullivan. “They give a good service. With our work, if you don’t get a service, the costs of standing idle are higher than anything else.”
O’Sullivan says that it is rare for a demolition contractor to use a crawler on city centre demolition. “You don’t usually have the space for it – space and logistics is the reason – but there was space here.”
He adds: “We have never used a crawler crane with a luffing jib before. We have used luffers before on tower cranes but not on crawlers. They [NRC] had to convince me it was going to work, but I’m happy that we made the right decision. It is better than a tower because there are no electrics, and there is more manoeuvrability.”
The 90t crawler was able to travel between the various buildings (the 100 tonner was only needed in one location). O’Sullivan says: “A tower crane would have to be on rails to cover such an area, but on a demolition site, that’s restrictive.”
As well as supplying the cranes and back-up, NRC also trained the Cantillon operator, who had not used a luffer before. “NRC were particularly helpful providing training on such a big crane. They were here for two weeks training him,” O’Sullivan says.
Cantillon is on course to complete all demolition work right on schedule by the end of this month. A webcam at www.newstreetsquare.com is tracking progress.
â— On another project, NRC has used two identical 100t Sumitomo SC1000 hydraulic crawler cranes to move 75m roofing beams at the Millennium Dome site in London, UK.
Anschutz Entertainment Group is developing the vacant dome into a 26,000-seat arena and entertainment complex. The venue is expected to be erected for five years.
Two cranes were required because one could not handle the length of the beams. Both cranes were expected to be on site for six weeks.
