Tunnel solution receives UK's top gong

Coffey Geotechnics has been awarded the prestigious Fleming Award by the British Geotechnical Association for its innovation on the €500-million-plus Limerick Tunnel in south west Ireland.

The award was bestowed on Webber Associates, which is an important part of the Coffey Geotechnics team in the United Kingdom, along with John Sisk and Son and MLM Consulting Engineers, for their work on the tunnel’s temporary works.

Director of Coffey Geotechnics’ UK business Marc Woodward said the project was particularly challenging and he was delighted senior principal Andrew Smith and his team received acknowledgement for their expertise.

“The construction of the tunnel required extensive and complex temporary works to combat deep soft sensitive soils, limestone bedrock and a six-metre tidal range.

“Our team worked in close co-operation with contractor and structural consultant to develop a solution for the approaches through which the tunnel elements had to pass to reach the river,” Marc said.

Coffey Geotechnics carried out complex analysis of the behaviour of all elements, including the walls and bulkheads. The solution adopted retained the excavations with combi-walls that were made up of 1.4-metre steel pipe piles that were alternated with pairs of sheet piles.

It was propped by struts at the top and partly by a concrete slab at the base of the excavation.

The team also responded to a major construction method change, when it was decided to excavate the northern approach in the dry rather than underwater.

“We were able to assess the implications of the proposed change to the construction method and recommend some necessary modifications to allow safe construction,” Marc explained.

The first tunnel element was floated out into the River Shannon on time in September 2008. The estimated completion date for the tunnel is 2010.

For more information contact:
Marc Woodward
44 0 142 387 8130
marc_woodward@coffey.com