The south Dublin Dart line between Merrion Gates and Greystones will require reinforcement works to stop the tracks from falling into the sea, Irish Rail has said.
The infrastructure works will cost at least €230 million to complete, according to Iarnród Éireann’s assessment.
The East Coast Railway Infrastructure Protection Projects scheme is designed to defend the Dublin to Rosslare coastal rail line, which carries Dart and mainline services, from erosion and flooding for the next 50 to 100 years.
Irish Rail says that “track washout”, where the sea erodes the land under the rail line, and wave overtopping have increased in intensity over the past 20 years.
“These instances have had significant performance impacts and safety consequences as well as major losses of land and habitat,” it says.
Irish Rail infrastructure programme manager Aidan Bermingham says that the rail will be “at risk in certain sections within 10 years” if nothing is done.
“Our studies have identified that in the last 20 years there have been more storm event incidences than there have been in the last 100 years thus increasing and accelerating the erosion rates and the climate change impacts,” he says.
Some of the most vulnerable sections of the line are around Dalkey and Killiney, as well as sections between the Merion Gates and Dún Laoghaire Harbour, and Bray Head and Greystones.
Bermingham says that at several locations along the line, more extreme weather and increased rainfall has eroded the facade of the embankment “to bring it to a point where it needs to be remedied and solutions to be put in place to protect it for the future,” he said.
“Without this project we would just be fixing it all the time and that incurs problems, including getting access to land.
“There is a risk there would be a pockets where the embankment would become unstable, and we would never let it get to that stage.”
Irish Rail has awarded a contract to carry out an environmental assessment and draft a preliminary design of the works to Jacobs Engineering.
This will be done ahead of planning applications filed with An Bord Pleanála and the Maritime Area Regulatory Authority for the work.
Bermingham says the process will involve “working closely with local communities”, to ensure the most appropriate and environmentally sustainable solutions are planned for each location.
The project, which will be the largest coastal protection scheme in northern Europe, is expected to be completed in stages within seven years.