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Tunnel Limerick, Ireland
Underwater tunnel in six-day cycles
As part of the M7 motorway development in the south-west of Ireland, the four-lane route crosses the Shannon near Limerick, a few kilometres before the river flows directly into the Atlantic. Centrepiece of the 10 km long ”Limerick Southern Ring Road” was the required tunnelling with a total length of 915 m. For this, two different customised PERI formwork solutions were used based on the requirements of the contractor as well as the construction sequence itself.
For the 28 concreting sections of the socalled immersed tunnel and the three adjacent construction phases in the north which were cast in-situ, a customized special formwork carriage was the most cost-effective solution. A total of five tunnel elements - each with a length of 100 m - were completely pre-fabricated in a dry dock positioned at the north portal, and then sealed off by means of bulkheads at the ends. After flooding the dock, the 100 x 25 x 8.50 metre reinforced concrete pre-cast segments, each weighing 20,000 tons, were floated out and then lowered into the exact position in a specially prepared channel on the river bed.
At the same time in the area of the south portal, an additional tunnel section was completed in six cycles. This took place using the cut-and-cover method. Due to the few concreting sections to be completed and the short rental period involved, the PERI VARIOKIT modular construction system was used because the use of mainly rentable standard elements meant less overall costs for the contractor.
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| PERI Systems In Use |
VARIOKIT System for Tunnel Construction
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Hannes Mauracher
Site Manager
“PERI provided us with the best technical concept and the most cost-effective solution. The results that we were able to achieve with the fomwork carriage were more than satisfactory. It allowed us to concrete each segment in a weekly cycle. What made our formwork partner all the more qualified was the technical support because we always received an appropriate solution to all of our detailed questions.”
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| Contractor: |
Limerick Southern Ring Road
DirectRoute (Limerick) Construction Ltd.
Strabag AG, John Sisk Son Ltd., Lagan Constr. Ltd.
Roadbridge Ltd. |
| Concreting and Shoring Work: |
Strabag International GmbH, Linz, Austria |
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Field Service:
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PERI GmbH, Deutschland
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PERI Press Release 06/2008
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