The Belfast-Derry railway line (called Derry ~ Londonderry line with NI Railways  ) runs from Belfast to Londonderry Derry in Northern Ireland.This line consists mainly of single track from just under Mossley West station up to Londonderry Waterside station with venues in Antrim, Ballymena, Ballymoney, Coleraine and Castle.
Services on Derry ~ Londonerry line runs on an alternating pattern to and from Belfast. The trains will change every hour between services from Great Victoria Street Londonderry Waterside (and vice versa), and a service from Great Victoria Street Coleraine, which then continues to Portrush via Coleraine-Portrush railway.
On weekdays, stations between Great Victoria Street, Coleraine every hour in both directions, with each outgoing trains alternating between a service to Londonderry Waterside, and a service to Portrush, except for some rush hour trains that stop at Coleraine. In the other direction, all the trains run every hour to Great Victoria Street, with the exception of a few late night and peak time services, that ends at Belfast Central. Stations between Coleraine and Londonderry Waterside served every hour in each direction.
On Saturdays, the service is still very much the same throughout the line during the week, except for a reduction in peak-time services.
On Sundays, all trains running between Great Victoria Street, Londonderry Waterside, except for the first and last service of the day, starting from or ending in Coleraine. Only seven trains go each way on Derry ~ Londonderry line on Sundays. 
All passengers traveling to Portrush on the Derry-based services, or to Derry at Portrush-bound services, must change Coleraine Station.
Before 2001 and the resumption of the Bleach Green Line, services operated via Crumlin, Glenavy, Ballinderry and Lisburn. The resumption of Bleach Green Line resulted in shorter travel between Belfast and Londonderry. A skeleton service continued on the Lisburn-Antrim line until 2003, when the line and its stations were closed. This section of railway is now used exclusively for driver training, for emergency diversions needed.
Recent history and future
In August 2011 it was planned to reduce services in Coleraine to Londonderry section to five services in each direction on weekdays, to facilitate safety improvement works in 2012. A reconstruction of the line was due to commence in April 2012, but the £ 75 million it was to be sold, was not tillgänglig.Detta resulted in opposition from supporters of the section who feared that the line would be permanently shut down. 
In October 2011, after years of uncertainty, DRD Minister Danny Kennedy moved funds from the A5 dual development project upgrade railway projects, allowing for a three Phase upgrade, which began in July 2012.
Phase 1 saw the line near the 9 months to completely relay two sections (Coleraine Castle and Eglinton Londonderry) of the stretch, extend the life of the remaining portion by converting the current hit track continuous welded rail, eliminating the wet spots and essential bridge repairs. This ended March 24, 2013 and the new timetable changes have resulted in a morning train to reach Derry before 9:00 for the first time since Northern Ireland Railways took control of the network in the 1960s.
Phase 2 was due to begin in 2014/15, but is currently delayed, consisting of the introduction of a passing track and resignalling route. It will see the signal cabins Castle and Londonderry turn, centralize signaling in Coleraine, and deliver every hour between Derry and Belfast. 
Phase 3 will include the entire relay tracks between Castle and Eglinton 2021 deliver half-hour services. 
Other future plans for Londonderry line includes a reinstatement of the double line of Antrim Ballymena, doubling the track from Monkstown Templepatrick, and any transfers of the route terminal in Londonderry.
Railway Technology function
Coleraine is a bascule bridge for railway over navigable river Bann.  Shortly after Castle station are two tunnels created during an event called the Big Blast in October 1845. Castle tunnel is 668 yards long and is the longest operating railway tunnel in Northern Ireland . After passing through a short opening train passes the shorter Downhill tunnel is 301 yards in length. 
The signal on the line from Great Victoria Street to slaught level crossing (just south of Ballymena station) is controlled by the Belfast Central control terminal. From Ballymena, are signaling and level crossings controlled by Coleraine signal cabin. After trains depart Coleraine an electric train crew system works between Coleraine and Castle. This is when the driver receives a token to access the portion of the line. Castle has its own signal cabin, which controls the signaling from up to Ballykelly, where the driver hand symbol to the signal controller and allowed another to make it possible for trains to move on to Londonderry. Londonderry also has a signal control terminal that controls the signaling from Eglinton.De most of Belfast to Londonderry line is controlled by color light signals, but Castle station still has semaphore signals from the somersault-type typical of the NCC functions.
After a full withdrawal of NIR NIR Class 80 and Class 450 trains, the line is now served by a combination of NIR NIR Class 3000 and Class 4000 diesel units.
- Jump up ^ “NI Railways Timetable – Derry Line, Winter 2012” (PDF).Translink. Be checked out three January 2013.
- Jump up ^ Northern Ireland Railways (March 2013). “NIR Service 3 Timetable”. Translink. Retrieved 19 March 2013.
- Jump up ^ “Kennedy calls for more money for Londonderry rail link.”BBC News. August 25, 2011.
- Jump up ^ “Londonderry Line” Andy Milne Rail Staff May 2012.
- Jump up ^ “Derry railway upgrade on the right track.” Retrieved July 11, 2013.
- Jump up ^ http://www.movablebridges.org.uk/BridgePage.asp?BridgeNumber=1100
- Jump up ^http://www.coastlinecastlerock.org/history/therailway02.php