The Dublin Area Rapid Transit system (DART) is an electrified commuter rail railway network serving the coastline and city centre of Dublin. The service makes up the core of Dublin's suburban railway network, stretching from Greystones, County Wicklow, in the south to Howth and Malahide in north County Dublin. The DART serves 31 stations and consists of 53 kilometres of track, and carries in the region of 20 million passengers per year.

The DART system was established by Córas Iompair Éireann [CIE] in 1984 to replace an ageing fleet of diesel-powered locomotives.

Since 1987 the service is operated by Iarnród Éireann, Ireland's national rail operator. Contemporary rolling stock on the DART network is powered by 1500 V DC overhead lines and uses the Irish 1,600 mm gauge.

An extension and modernisation project branded as DART+, which is proposed to triple the electrified network in size, began design work in 2019.

The section of trackbed between Dún Laoghaire and Dublin City was originally laid out as part of the Dublin and Kingstown Railway, Ireland's first railway. This line was later connected with the Belfast mainline to the north and Wexford mainline to the south and joined the Harcourt Street line at Shanganagh Junction. The scenic views from the railway over Dublin Bay at this point have been favourably compared to those on the Gulf of Naples and have resulted in trips to Killiney Hill and Greystones along the line becoming popular tourist attractions.

Prior to electrification in 1984, the line was operated using 1950s era CIÉ 2600 Class rail cars which had been converted in the early 1970s to push-pull operation. These diesel-powered trains were powered by a CIE 201 Class locomotive with a driving trailer carriage on the other. This service was notoriously uncomfortable, unreliable and overcrowded. By the late 1970s, the need for an urgent upgrade to the system had become apparent as the 2600 Class railcars were in poor condition. Replacement parts had become increasingly difficult to obtain due to the age of the rolling stock and its conversion to push-pull operation, which had been intended as a temporary measure until a more permanent solution could be established, had come to the end of its serviceable life.

In advance of electrification, three new stations at Sandymount, Booterstown and Salthill and Monkstown were added to the network in 1984. Sandymount and Booterstown were each built at the sites of a previous station while Salthill and Monkstown were built near the site of the original Kingstown railway terminus, between Seapoint and Dún Laoghaire.

As electrification work was undertaken from 1981–1982, a spur which had served the ferry port at Dún Laoghaire was disconnected from the mainline as the installation of overhead power lines to service the harbour would have necessitated the lowering of the track which travelled through a portal south of Dún Laoghaire station.

Early DART services ran from the north-eastern suburb of Howth, through Connolly, Tara Street, and Pearse stations in the city centre and on to Bray which lies on the border between Dublin and Wicklow. This route remained unchanged for almost sixteen years at which point the line between Bray and Greystones was electrified. Further electrification of the line took place between Howth Junction & Donaghmede and Malahide, the northernmost DART station, on the Belfast mainline.
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