The Phoenix Park Rail Tunnel, a railway tunnel in Dublin funded by the National Transport Authority, reopens to regular passenger traffic on November 21, 2016, improving services for rail commuters in Kildare and Dublin.

The tunnel is built in 1877 and begins at the Liffey Railway Bridge near Heuston Station, running underneath the Phoenix Park for 690 metres before re-emerging close to the junction of the Infirmary Road and North Circular Road. It joins with the Dublin-Sligo railway line near Glasnevin, before continuing to Dublin Connolly station.

The tunnel is originally built by the Great Southern and Western Railway company to connect Kingsbridge station (now Heuston Station) to the Dublin Docklands and is primarily used for freight. Historically the line has not been used for regular passenger trains, with most traffic through the tunnel being freight or carriages and engines shunted between Connolly and Heuston for maintenance. It has occasionally been used for special passenger services, including traffic for major Gaelic Athletic Association fixtures.

The tunnel reopens to regular passenger traffic on November 21, 2016. As of late 2018, this traffic is predominantly weekday services.

(Pictured: Southern end of the Phoenix Park Tunnel, Dublin, Ireland)