Dublin–Cork railway line
It is one of the longest in Ireland at 266 km. The line is utilised by both InterCity and Commuter services. Services to Waterford branch off at Cherryville Junction, after Kildare, and to Westport and Galway after Portarlington. Although there are some direct services to Limerick, most services require a change at either Limerick Junction or Ballybrophy traveling onward via the Limerick-Ballybrophy railway line. Services to Tralee via Killarney and Farranfore (for Kerry Airport) run from Mallow. Commuter services run on both the South Western Commuter line between Dublin and Kildare or Portlaoise, and Cork Commuter line between Mallow and Cobh.
Iarnród Éireann, the Irish state railway company, has invested heavily in improving the infrastructure and rolling stock. It has had both its track and signalling upgraded in the last few years thanks to funding from the government's National Development Plan - beginning in 1977, the line was upgraded to continuous welded rail, while the introduction of Centralised Traffic Control means that signalling is controlled from a single location at Dublin Connolly station.
In 2006, the first of 67 new Mark 4 coaches were introduced on the route as part of a €117 million upgrade of rolling stock. These seven new 8-car sets provide an hourly service frequency between Dublin and Cork.
Although Dublin Heuston is the terminus, the line connects to Dublin Connolly via the Phoenix Park Tunnel. This route is primarily used for freight services and rolling stock movements to the main Iarnród Éireann works at Inchicore, just south of Heuston. However, it is occasionally used for special passenger services to Dublin Connolly, usually for Gaelic games events at Croke Park.
Built by the Great Southern and Western Railway (GS&WR), it connects the largest and second largest cities in the country. It connects with lines to other destinations, including Galway, Waterford, Westport, Limerick and Tralee. Construction began in 1844, when the GS&WR built a line from Kingsbridge Station (now Heuston Station, Dublin) to Cashel in County Tipperary, later extended to Cork. Amalgamations between the GS&WR and other smaller railway companies in the south led to the line gaining connections to other population centres. A branch from Portarlington to Athlone was built to connect with the Midland Great Western Railway to Galway.
There are 14 daily services between Cork Kent - Dublin Heuston - Cork Kent (Monday - Saturday) Departing Hourly on the hour. There are 13 daily services between Dublin Heuston - Cork Kent - Cork Kent (Monday - Saturday) Departing Hourly on the half hour (plus other early morning services Monday to Friday) 
There are ten daily services between Cork Kent - Dublin Heuston - Cork Kent (Sunday)
The line has been getting a major upgrade, resulting in major disruption and cancellations on many weekends and speed restrictions affecting the punctuality of trains. The objective is to increase the sections of line capable for 100 mph operation and thus provide faster services to compete with the M8 motorway. The following is a summary of the main works involved:
- Awbeg River bridge renewal: The railway crosses the Awbeg river near Charleville, Co. Cork. The line is currently subject to a 25 mph speed restriction over this bridge. The bridge will have to be replaced, resulting in the temporary diversion of the Awbeg River and other site preparatory works in 2011. The renewal will take place over the October Bank Holiday Weekend. It will result in the line being closed and bus transfers in place. The project will require use of two of the largest cranes in the country and a new access road had to be built to accommodate such cranes. The project will cost an estimated €1 million.
- Kildare Route Project: This involved increasing the number of tracks from 2 to 4 between Cherry Orchard & Hazelhatch. It also included The renewing of the two old tracks. There is now a Down Fast, Down Slow, Up Slow & Up Fast lines. This section was cleared for 100 mph in November 2010. Project completed in March 2011.
- Limerick Junction Reconfiguration: Currently there is a 25 mph limit through Limerick Junction. This project involves the provision of new signalling and new track layout in the Limerick Junction area. It also includes the automation of Emly gates where there is a limit of 80 mph in a 100 mph section. These will be lifted so to increase speed to 60 and 100 mph respectively through these areas. Completed January 2011.
- Relaying with 60 kg rail: All relaying on the Dublin/Cork line in the future will involve using the 60 kg rail. It is a much heavier rail giving a smoother ride in trains. The section between Portarlington and Portlaoise has been relayed with the 60 kg rail. Most of this section has now been cleared for 100 mph operation. 60 kg rail is being laid on many other smaller sections on the line and this is continuing. Relaying commenced in 2011 Starting from Sallins and working back towards Hazelhatch and Celbridge. There is currently many speed restrictions in this area as a result. There is little disruption as work is done by nighttime & this can be seen by the halogen lights placed along the line in this section.
- Rehabilitation works: Rehabilitation works are being undertaken on some existing sections of track. This includes excavation, renewing drainage, installing a geo-textile membrane, replacing broken sleepers and renewing side worn rails. This was carried out on the 25-mile section between Newbridge and Portlaoise. Speeds have been restored to 80/90/100 mph. These works are ongoing in other areas.
- Lisduff Area Renewal: Where the line passes through Lisduff Co.Tipperary there is the quarry used for ballast for the railway. There are railway sidings leading off the main line into it. The turnouts and crossover in this area have severe curvature & are life expired. There has been a 50 mph limit through this area for a long time. As part of the lines upgrading, these turnouts and points will be completely renewed. Speed limit will then be increased to 90 mph. The new points & turnouts have been constructed, They are currently placed alongside the line, awaiting installation later in 2011. This will require the line to be closed for a period. Completion due late 2011.
- Other Works: Other works done or ongoing are: Renewal of Track layout Sallins (2009); Renewal of Points & provision of faster turnouts, Cherryville (2010); Portarlington Rebuilding to increase line speed here from 30 mph to 80 mph (2008), Renewal of Signalling & Track, Portlaoise (2010) & Excavtion of boggy area, Pile driving and track renewal, Ballybrophy (2009)
In September 2011, Iarnród Éireann received government funding of €1 million to continue the improvements on the Dublin – Portarlington section of this line later in 2011.
In September 2011, Iarnród Éireann announced a €175 million major investment programme, designed to further accelerate upgrading works on Intercity Routes, In particular the Dublin - Cork line. From 2012 upgrading will intensify to include the following:
- Sallins - Cherryville Realigments: Currently in this section, in particular around the Curragh, there is much curvature in the line, resulting in an 80 mph limit in these areas. This project will see the Railway realigned through these areas to remove the curves & increase the speed limit to 100 mph. There will also be relaying of track in this section.
- Portlaoise - Limerick Junction Relaying: This long section of line currently has a maximum speed of 90 mph, with slightly lower limits in spots. The majority of this section will have works to the trackbed & Relaying to increase the speed to 100 mph. There will also be an elimination of level crossings & upgrading of points nearer Limerick Junction.
- Irish Rail Dublin Hesuton Station Website
- Irish Rail Cork kent Station Website
- Rail Vision 2030
- Irish Rail Investment and Projects
- http://www.irishrail.ie/index.jsp?p=123&n=209 Irish Rail Intercity Fleet
- http://www.irishrail.ie/index.jsp?p=119&n=147 Latest Irish Rail Printable Timetables