Diesel traction is the sole form of motive power in both the IÉ and NIR networks, apart from the electrified Howth/Malahide-Greystones (DART) suburban route in Dublin.

NIR and IÉ both run suburban services using diesel multiple units (DMUs) – these are termed railcars in Ireland (see rail terminology).

IÉ DMUs operate all InterCity services apart from Dublin to Cork and some Dublin to Belfast services[3] There are 234 22000 Class carriages in total, being formed into the following sets: Features of the InterCity railcar fleet include:[citation needed] The primary DMU classes in operation include the 22000, 29000, 2800, 2600, 3000, and 4000 series.

These units primarily operate on suburban routes in the Greater Dublin area, offering a seating capacity of 185 per set.

Initially deployed on regional services, these DMUs have been reassigned to various routes based on operational requirements, each set providing seating for 85 passengers.

Each set contains (in order): The Mark 4 trains have blue tinted windows, which help to create a cool journey for the passenger, electronic route maps showing train progress, electronic seat reservation displays and power points for laptops, or recharging tablets, MP3 players or mobile phones.

Citygold customers on this fleet have the added features of adjustable seating, greater room and comfort and in-seat audio entertainment.

The Dublin to Belfast 'Enterprise' service is operated jointly by IÉ and NIR with rolling stock from De Dietrich, commissioned in 1997.

[5] NIR also had a number of refurbished Class 488 carriages acquired from the Gatwick Express service and converted to run on the Irish 1,600 mm (5 ft 3 in) gauge.

Please note the following when examining routes: Stations served on this line are This was known as the 'Premier Line' of the Great Southern and Western Railway (GS&WR), being one of the longest routes in the country (266 km or 165 miles), built to a high standard and connecting to Galway, Limerick, Waterford and County Kerry, as well as to Cork.

[citation needed] A fourth track is planned between Park West-Cherry Orchard and Heuston which is also intended to further reduce journey times.

The 16:37 Dublin Connolly to Rosslare Europort Mondays to Fridays journey offers connectional opportunities into ships to Wales and France.

It involved the relaying of 58 km of track, rebuilding bridges, installation of signalling systems, level crossing upgrades and building the stations.

As a result of this study IÉ has committed to allocating additional rolling stock to the line as part of its ongoing fleet replacement programme.

[13] Three suburban routes run on 20-minute frequencies in and out of Belfast Grand Central, these routes then pass through Belfast Lanyon Place before continuing onto destinations at Bangor, Derry and Larne Stations served on this line are: The service to Derry has suffered from a lack of funding over recent decades.

the department has partly completed a plan in place for Regional Development, for relaying of the track between Derry and Coleraine by 2013, which includes a passing loop, and the introduction of two new train sets.

The InterCity route, despite being mostly high quality continuous welded rail, is shared with suburban services outside both Belfast and Dublin.

Unlike most other locomotive-hauled rolling stock in Ireland, generator vans were not part of the train – even the DVTs did not supply power.

[citation needed] Freight services no longer running include ammonia trains (from Shelton Abbey, Wicklow–Cork due to the closure of a fertiliser plant),[citation needed] nationwide bagged cement and beer keg freight,[citation needed] gypsum loads (Kingscourt–Dublin), and bulk cement (from cement factories at Platin near Drogheda and Castlemungret near Limerick to silos at Sligo, Athenry, Cabra, Cork, Waterford, Tullamore and Belfast).

[citation needed] Other losses included services carrying fertilisers, grain, tar, scrap metal, molasses and coal.

[citation needed] Remaining freight traffic is supported by an agreement with Coillte to increase timber trains from Ballina to Belview from three to four weekly.

There are a number of museums, most concerned with the 3 ft (914 mm) gauge, and restored railway stations around Ireland: A public consultation for a cross-border review of the inter-city railway network was launched jointly by the Irish Minister for Transport and Northern Irish Minister for Infrastructure in November 2021,[24] with over 8,000 responses to the consultation.

The section between Athenry and Claremorris is recommended to be opened under the All Island Strategic Rail Review, and has been proposed by the Government as part of the Trans-European Transport Network.

The reopening of the line is recommended to be opened under the All Island Strategic Rail Review,[25] and has been proposed by the Government as part of the Trans-European Transport Network.

Its route proposes mainly elevated tracks in the greater Swords area, with a tunnel running from north of Dublin Airport to Charlemont.

[40] In July 2020, during a North/South Ministerial Council meeting, it was proposed to undertake a feasibility study on a possible high-speed line between Belfast and Cork via Dublin.

[41] In February 2018 the Irish Independent reported that the National Transport Authority favoured building four new DART stations, three linked to a new DART operation from Heuston, including near Cross Guns Bridge in Cabra, within Glasnevin, and at a Docklands location, along with a new station north of Bray, at Woodbrook.

[46] In 2017, increasing demand led Iarnród Éireann to issue tenders for the refurbishment of 10 2700 class sets, which had been held in storage for 6 years with the intention of planned use around Limerick from early 2019.

[47] As of early 2018, Iarnród Éireann announced plans to procure new DART trains capable of operating on both diesel and electric power.

In 2021, supported by the National Transport Authority, Iarnród Éireann partnered with Alstom to develop new electric and battery-electric trains, which are scheduled to enter service in 2026.