Tuesday 25 October 2016

Bridge too far as weather ravages vital links

Published 27/11/2015 | 02:30

Connemara’s Leenaun Bridge was devastated in 2007
Connemara’s Leenaun Bridge was devastated in 2007
Connemara’s Leenaun Bridge
Damage to Cloonbony Bridge in Co Clare

Key infrastructure including bridges, railway lines and water treatment plants are under increasing threat from climate change.

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Extreme weather, including torrential rainfall, is already having an impact - Transport Infrastructure Ireland (TII) has warned that drainage channels and culverts around older bridges may have to be replaced as they are unable to cope with increased volumes of water.

And Irish Rail has warned about flooding on the Wexford line, while Irish Water said that rainfall would hamper the ability of plants to provide clean and safe drinking water.

During threatened summer droughts, lower river flows would reduce the availability of water for abstraction, the company said.

Flooding could impact on raw water quality, making it more difficult to treat, and it was working on an adaptation policy to be published next year.

Ireland is expected to experience more extreme weather events as climate change takes hold, including violent winter storms and increased volumes of rainfall.

This can have serious implications - in 2007, the Leenaun Bridge in Connemara was washed away during a flood event, despite passing an inspection. Last month urgent repair works were needed at a bridge at Cloonbony in Clare, which had subsided after waters eroded the foundations during heavy rainfall and floods.

The works required the road to be closed for more than a month.

The head of structures at TII, John Iliff, said some 700 of the 3,000 road bridges were older, masonry structures.

"They would be our biggest concern," Mr Iliff said.

"The new bridges don't have problems, but in the west you have older structures, some 150 to 200 years old, and designed in the days of the horse and cart but now exposed to major loads like buses and HGVs. They're not designed for it, but are well able for it.

"I think we're seeing more instances (of issues) and a lot of work. The existing culverts or drainage channels may not be appropriate for now."

Each bridge across the network undergoes an annual inspection, and a more in-depth examination every six years, but despite passing an inspection, the Leenaun bridge was washed away during an extreme storm.

"With torrential downpours, and a landslide up the mountain, it brought rubbish including trees with it and they got caught up in the arch," Mr Iliff said. "When you have jets of water down the side, they can wash out the foundations. It could happen over three of four months, but in Leenaun it happened in a day."

Preventative works have been undertaken at bridges in Kerry, Limerick, Mayo, Donegal, Roscommon, Cork, Tipperary and Meath in recent years after scour - or erosion caused by water - was discovered. The works were carried out to prevent further damage, and no roads were closed.

Irish Rail has also raised concerns about the Wexford line, which is threatened by coastal erosion, and flooding which is impacting on the network with "increasing prevalence", a spokesman said.

"Climate change and its adverse impacts is something that is impacting now. Ultimately, the issues will come down to funding," he added.

Irish Independent

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