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The building of the Corrib tunnel under Sruwaddacon Bay in north Mayo has been progressing steadily since January 2013. The tunnel, which will be 4.9kms long, is being excavated by a specially designed tunnel boring machine (TBM) called ‘Fionnuala’.  One of the key elements in the smooth operation of the TBM is the small locomotive train which transports personnel and materials in and out of the tunnel on a 24/7 basis.

As ‘Fionnuala’ moves forward, a series of 1.2m wide concrete rings made up of precast interlocking concrete segments are erected.  These concrete rings will eventually line the entire tunnel and have to be transported into the tunnel on a daily basis by train.  The concrete segments are loaded in the tunnel’s start shaft using a giant gantry crane.  Tools, equipment and other materials are also brought into the tunnel on the train for use by ‘Fionnuala’s’ machine operatives.  

At each shift change, a maximum of 12 people board a small personnel carrier which is fixed to the train.  The locomotive then transports the tunnelling team into the tunnel to where ‘Fionnuala’ is excavating.  Those tunnellers who have completed their shift on ‘Fionnuala’ are then transported back to the surface using the same carriage.

The diesel-operated train uses small tracks, which have been installed on the base of the tunnel.  As ‘Fionnuala’ progresses further into the tunnel, two passing sections of track will be installed to allow for a second locomotive to pass in the tunnel at the same time.

It is the train driver’s job to ensure that the people who work on ‘Fionnuala’ and the goods required inside the tunnel are transported in a safe and secure manner.  To achieve this, the driver is in constant communication with the team on ‘Fionnuala’ and with colleagues above ground on the Aughoose site who monitor all movements in and out of the tunnel, on CCTV cameras.

The Corrib locomotive:

  • Has one driver at a time, 3 in total working on rotation
  • Is powered using diesel fuel
  • Can transport a maximum of 12 people onboard a specially created carriage
  • Works 24/7 to ensure continuity of supply to ‘Fionnuala’