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Tunnelling Update - February 2014
Trains travel over 250km underwater daily
A pair of small locomotive trains is transporting materials and personnel over 250km under Sruwaddacon Bay in north Mayo on a daily basis. The trains are a key component in the building of the 4.9km long Corrib tunnel, which will carry the Corrib onshore gas pipeline from the landfall at Glengad to Aughoose, from where it continues overland to the Bellanaboy Bridge Gas Terminal.
The tunnel, which will be longer than the Dublin Port tunnel when completed, is being excavated using a specially designed tunnel boring machine (TBM) called ‘Fionnuala’. As the TBM has progressed passed the halfway mark (2.5km), a specially designed section of track known as a ‘California Switch’ was installed to enable two trains to operate within the tunnel at the same time.
The two small locomotives are covering a significant distance and this increases daily as the TBM gets closer to its final destination, the landfall site at Glengad. “The trains are essential for ensuring that the supply of personnel and materials remains uninterrupted” says Kieran White, a tunnel engineer with Shell E&P Ireland Limited (SEPIL).
Every hour approximately two trains leave Aughoose carrying their payload of the concrete ring segments that are used to build the tunnel as well as additional sections of railway track that are laid on the base of the tunnel as the TBM moves forward. Tools and other essentials including food and water for the TBM crew are also transported to the front end of the tunnel on a daily basis.
“A considerable amount of planning is required as safety is paramount in everything that we do” explains Kieran. “Installing the ‘California Switch’ is another milestone that has been achieved on what is one of the most challenging and interesting engineering projects in Ireland.”