The collapse of the bridge in County Dublin on the Dublin-Belfast rail line will cause chaos for over 20,000 commuters now that Ireland’s transportation authority says the line will be shut down for months.

Iarnród Éireann has released details of its plans for Irish passengers following serious incident, in which a 20-meter portion of the viaduct over the Broadmeadow estuary between Malahide and Donabate fell into the sea.

The company is carrying out a full investigation into the collapse, and said on Saturday that the bridge would not reopen for at least three months.

Northern rail commuter services in Ireland, which is used by over 20,000 people every day, have been seriously disrupted.

Ireland’s Construction Industry Federation is calling for railway bridges across the country to be inspected.

The federation’s director, Don O’Sullivan, told RTE: “Most of these bridges were built in the nineteenth century. It’s the second sudden collapse that we’ve had in recent years.

“The bridges need to be thoroughly assessed. Where necessary, there needs to be a bridge-strengthening and reconstruction program undertaken.”

In the meantime, it was announced that limited shuttle service will operate between Drogheda and Skerries, while passengers traveling between Dublin and any station north of Malahide are being advised to travel by Dublin Bus or Bus Éireann.

What would have been Ireland’s worst rail disaster to date was averted around 6 p.m. Irish time on Friday thanks to train driver Keith Farrelly, 33, who spotted subsidence on the Dublin-Belfast line as he was crossing over the viaduct, quickly stopped his train and immediately reported it.

Farrelly described the experience to the Irish Independent, saying: "The first inkling I had that something was wrong was when I noticed water splashing up to a high level. In that location, it's not a normal thing to happen, so I looked at the northbound line and saw that the viaduct was giving way and that the track was hanging.

"The Dundalk train had just gone over the bridge – it was a very close call.

"I saw the bridge start to collapse as I was going over it, it was a scary situation, it was pretty hairy I tell you . . . it was surreal. I was just relieved that we got past. I couldn't believe what I was seeing, the waves were coming up over the side of it, I thought I was seeing things.”

The heroic driver added: “It was such an unreal sight, I started thinking to myself 'did I really see that', but when I walked back I saw it clearly, and my legs just went to jelly with the shock.

"I'm just glad that all of us on board walked away from it safely.”