Compressors from Atlas Copco are playing a key role in the £500m upgrade of London’s Tottenham Court Road underground station.

The major upgrade project, which is being carried out for Transport for London (TfL) as a joint venture between Taylor Woodrow – Civil Engineering Division of Vinci Construction UK – and BAM Nuttall, will be complete in 2016 with an enlarged ticket hall six times the size of the present unit, new station entrances, additional access points to the Northern and Central Line platforms to reduce congestion plus 14 escalators and six new lifts to provide step-free access.

Two Atlas Copco compressors positioned on the site’s surface have had an important role to play below ground – providing compressed air for drilling and chipping tools but mainly being employed in the application of sprayed concrete tunnel linings.

The need for guaranteed quality air, total machine reliability, 24/7 availability and cost efficiency were amongst the key deciding factors in choosing equipment from Atlas Copco. As a result, the decision was taken to enter an agreement that provided two new stationary, Elektronikon controlled, fully weather-proofed and winterised Atlas Copco GA 132FF rotary crew compressors.

The Atlas Copco model GA132FF is a single stage, fully integrated rotary screw compressor that delivers 7bar oil-free dry air at the rate of 400l/s via a built-in refrigerant dryer, a three stage air/oil separator and oil filters housed within the compressor canopy.

High quality air is essential to the successful delivery of uncontaminated, fibre-reinforced liquid concrete to vertical and curved overhead surfaces through the shotcrete process. Compressed air is introduced at the delivery nozzle to spray the concrete mixture onto the receiving surface. This wet gun procedure produces less rebound and waste with the advantage that larger volumes can be placed in shorter time.

By installing the compressors Taylor Woodrow BAM Nuttall benefited from being provided with two completely fit for purpose machines, incorporating all the drying and filtration equipment needed to provide the required level of oil-free air. As Ben Thomson, Taylor Woodrow BAM Nuttall tunneling engineer explained, “We felt it was the right decision to go with Atlas Copco who provided us with two new compressors and the reassurance of continuous, reliable performance which is vital to our below ground operations. Guaranteed air quality was the primary deciding factor – oil and concrete are not a good mix.”

Early phases of the Tottenham Court Road project saw utility diversions completed, buildings on the site purchased and demolished and, by 2010, the main excavation and construction work under way to create space for the upgraded station complex. This stage was followed by an eight month closure of the Northern Line platforms at Tottenham Court Road to allow tunnels to be reshaped to make room for new escalator and platform access. The current phase involves construction of new underground structures that include tunnels, the new ticket hall and an interchange ‘box’.

Once the current phase involving the shotcreting duties of the compressors is completed, the two units will be transferred for operation at the joint venture’s other major transport upgrade project at London’s Victoria Station. The first construction phase for the London Victoria station upgrade commenced in 2011 and the project is scheduled for completion by 2018.