01 September 2002

Atlas Copco portable compressors are supplying vital air power for underground work on the latest extension to Istanbul's metro network.

Currently under construction, the extension to the underground metro network is a 10-km-long section between Taksim and Yenikapi.

Separated by the waters of the Golden Horn river, the two stations will be connected by a line which will include eight additional stations, and involve 5 km of tunnel boring, 3.7 km of tunnel drilling, cut and cover workings and 460 m of bridges.

A consortium comprising Yuksel Construction, Guris, Reha and Basyazicioglu is constructing this section. The consortium has sub-contracted all drilling, tunnelling and concreting work to local firm Ozgun Construction.

Ozgun has constructed the initial tunnels from Taksim station to the first stop Sishane, a distance of 3 km, and onwards towards the Golden Horn, a further 1.5 km.

This tunnel section of the metro has been drilled, as getting a TBM (tunnel boring machine) into the site would have proven impossible.

The area is a renowned historical neighbourhood with many narrow lanes, and tunnelling has had to be stopped many times to allow for inspections of building's foundations.

Getting equipment into the site has been problematical. Another problem Ozgun has had to overcome is the supply of air-power for pneumatic drilling machines and shotcreting units.

Because of a lack of ventilation shafts and the number of historical buildings above the tunnels, the company is using Atlas Copco portable compressors based above ground that supply air power via a network of pipes reaching a distance of 3.5 km.

According to a company spokesman, ...zgun wanted Atlas Copco compressors because of their reliability, even though these diesel-powered units would have to remain above ground.

Currently based at ground level near to one of the few entry shafts for the underground work in progress - near Sishane station - the contractor has two Atlas Copco portable compressors.

One XAHS285 unit working at 12bar is supplying air power for two pneumatic drilling rigs. With an actual free air delivery of 17 cu m/min, the unit has been working 24 hours a day as tunnelling progresses underground.

At Sishane, the station will be 32m underground while lift shafts and stairwells, as well as platforms and tunnels, amount to 2km of workings at this station alone.

All tunnels in this area are being shotcreted by one machine. This unit needs 14 cu m/min of air power and is being powered by an Atlas Copco XAMS295 portable compressor. This compressor working at 8.6 bar has an actual free air delivery of 17 cu m/min.

Ozgun also has two Atlas Copco electric compressors based at Sishane supplying on-site power for site offices and general maintenance yard machinery.

The units, a GA160 and a GA110, are far cheaper to run than using mains electricity, according to the contractor.

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