Ireland plans to add two tracks to the 14 km corridor between Dublin Connolly and Malahide under the FourNorth railway expansion, a project expected to cost more than €1 billion.

A Class 22000 train standing beside the platform at Malahide railway station
A Class 22000 DMU at Malahide station; illustrative image, not current FourNorth works. Photo: Alessandro Ambrosetti / CC BY 2.0

FourNorth would rebuild ten stations

Iarnród Éireann is preparing a public consultation for later in 2026. The process will help determine the precise configuration of the two additional tracks before detailed design and authorisation work advances.

FourNorth would also require extensive modernisation at ten stations along the Northern Line. Some options could affect nearby gardens, land or other private property, although the operator will contact potentially affected owners only after more detailed plans are available.

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More capacity for four types of rail service

Enterprise, Northern Line commuter, DART and freight services currently share the same two tracks on one of Ireland’s most congested railway corridors. Even small timetable deviations can therefore create delays across several services.

The additional tracks are intended to support faster Dublin–Belfast Enterprise trains, improved commuter services, further DART expansion and fewer operational conflicts between passenger and freight trains.

The project is also included in Iarnród Éireann’s Rail2050 plan⁠, which identifies four-tracking between Connolly and Malahide as part of the planned development of Dublin’s urban rail network.

Design work is funded, but construction is not

An EU procurement notice⁠ records a €2.49 million multidisciplinary consultancy contract with Arup, concluded in December 2024. Its scope includes preliminary design studies and preparation of the preliminary business case.

The Connecting Europe Facility selection⁠ allocated a maximum EU contribution of €1.29 million for FourNorth studies. Ireland’s Department of Transport is also supporting the preliminary stages, but funding for the complete construction programme has not been secured.

An initial assessment places the total investment above €1 billion. The 2024 All-Island Strategic Rail Review previously estimated €700 million to €1 billion at 2021 prices for the Dublin–Clongriffin section alone, which represents approximately two-thirds of the corridor now under consideration.

Interim works will precede FourNorth

Before the additional tracks are built, authorities plan passing loops and turnback facilities at Mosney, Skerries, Malahide and Clongriffin. These measures are intended to provide greater timetable flexibility and limit the spread of delays.

Design, consultation and statutory approvals will require several years, while construction work is expected to continue into the early 2030s. The public consultation and preliminary business case will determine the preferred layout, refined cost and potential funding arrangements.

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