In the 19th century, as a part of the British Empire, Ireland was an early adopter of railways. The country's first line, built in 1834 between Dublin and Dun Laoghaire, then separate cities, was also one of the world's first commuter railways. It ferried passengers up and down the short ten kilometre hop between the two settlements. In 1844, the line was extended to Dalkey using "Atmospheric" technology, which meant that the train was propelled by a vacuum tube. This operated until 1854 when it was converted to a normal type and incorporated into the rest of the line, followed soon by an extension to Bray.
Over the next few decades, the rest of the railway lines in Dublin were constructed, and as the 20th century dawned, reached their height of popularity. Many were constructed as narrow gauge light railways with half-size locomotives. This had the advantage of allowing much more twisting and turning of the track, as well as steeper gradients.
The reputation of the railways was greatly tarnished during the Second World War as they had to convert to peat due to coal no longer being available, and journey times soared. After the war, they entered a long period of decline.
One by one, lines were closed, particularly in the 1950s and 60s. All the narrow gauge and light railways went, as did many heavy rail connections like Athlone to Mullingar and Limerick to Galway. Controversially, a rail line entering Dublin from Bray and terminating in Harcourt Street in the inner city got the chop too in the 1950s. This line had been a commuting artery, though a little-used one by that time. This at least would make a comeback in the 21st century.
It was assumed, as elsewhere, that car travel was the replacement for rail services and that railways would soon disappear, with only basic services retained for social reasons.
In the 1970s, policy changed and it was recognised that Dublin would benefit from reopened and rejuvenated rail services. The government prepared a plan for railway investment in Dublin in 1975 called the DRRTS (Dublin Rapid Rail Transport Study). This recommended the building of a network of electrified railway lines throughout the city, including one following the present Luas Red Line path down to Tallaght, together with a certain number of light rail lines, including one to the working class suburb of Ballymun. The bulk of new rail services would be achieved by electrifying existing lines.
A stripped down version of these plans was underway by the end of the decade and in 1984, the DART opened, an electrified rail service between Howth and Portmarnock in the north, and Bray in the south. Although derided as a white elephant at a time, upon launch the service was instantly popular, and passenger levels slowly grew over the years. Extension and capacity increase did not keep pace however, and it was not until 1999 that the DART was extended to Malahide in the north, and Greystones in the south.
With the Celtic Tiger economic boom having been in full swing for several years, in 2000 the government unveiled a document called A Platform For Change (PFC). It set out the medium to long term plans for public transport development in Dublin. It envisaged a dense network of metro lines, light rail lines, and heavy rail upgrades to create a unified, well integrated network of public transport lines for Dublin. It incorporated much of the lines identified in the DRRTS, but in modified form. For example, the DART line to Tallaght was now a light rail line. The plan's timeline ran from 2000 to 2016. Crucially, it also included for the first time, a rail connection to Dublin Airport.
In the early 2000s work began on two light rail lines for the city, and in 2004, the Red and Green lines opened. Titled "Luas", Irish for speed, one used the old Harcourt St railway alignment heading south out of the centre, protected since its closure, while the other used an alignment reserved in the 1970s for a DART down to Tallaght.
Sadly, by 2005, it was becoming very clear that the PFC plan would not be achieved by the target date of 2016, and that in fact very little progress had been made by this time. In response to this, the Government reorganised and reannounced the plan to invest in rail infrastructure and put out the Transport21 (T21) plan. (The website used be at www.transport21.ie but as of 2024 the domain has been taken over.) This was a 10-year plan covering the years up to 2015 and incorporated the main elements of the PFC, including the already constructed Luas lines. Unfortunately, the remaining parts were pushed out to an as yet unspecified second phase. The plan ran from 2005 to 2015 - in other words, it aimed to do a lot less than PFC in the same amount of time.
On the other hand, the projects that were included were all of high utility and the resulting network, though smaller than originally envisaged, would nonetheless solve many of the eternal traffic congestion problems that Dublin has long suffered from.
The two largest projects under T21 were a plan to connect Heuston Station and the area north of Connolly Station with an underground tunnel known as the Interconnector, and the underground metro line to the airport and onwards to the northern suburb of Swords known as Metro North. Both of these large tunnel projects were due to commence construction in 2010. The Interconnector would allow a large scale reorganisation of the heavy rail lines in the capital, creating a 2-line DART network. Creating a huge increase in DART capacity, it would allow lines to be extended far out into the city's outlying towns as well as the creation of a new line serving the large outlying town of Navan.
Slow progress was made. A ramp-up from low construction activity to high was never achieved.
Projects were announced multiple times by politicians, taking years to move from preparation to build.
When T21 was announced, the implementation dates were listed as part of the documentation.
Small scale projects would be completed by 2008, with large-scale coming in from 2012-2015.
In the event, things did not come to pass as envisaged. The project pipeline was dogged by inexplicable delays, reports on reports, litigation and cost rises.
By 2008, virtually nothing had been achieved. It was now clear that the small scale projects would be completed during 2009-2011 with the large ones in 2015-2016.
However, the 2008 economic crisis hit Ireland particularly hard. The government bailed out the banking system and had to be bailed out itself by a troika of the EU, the IMF, and the World Bank.
Many years of austerity followed, with capital budgets wiped out.
In 2011, work was due to begin on Metro North in 2012, with a start date for DART Interconnector uncertain.
In 2013, Metro North had no defined start date, though the government were still committed to it in principle. The Interconnector was also uncertain.
It was not until 2015 that a new properly funded investment programme was launched. Details of this are documented on the Current Rail Programme page.