Butetown Branch Line

The Butetown Branch Line, also known as the Cardiff Bay Line, is a commuter railway line in Cardiff, Wales from Cardiff Bay and Cardiff Queen Street. The service pattern used to comprise a mixture of shuttle services along the branch and through trains along the Rhymney Line to Caerphilly, or the Coryton Line to Coryton, but since December 2005 is a shuttle service from Queen Street station.

Originally a portion of the Taff Vale Railway's main line to Cardiff's Bute Docks, in 1922, it was absorbed, along with the neighbouring Rhymney Railway, into the enlarged Great Western Railway. With the decline of coal traffic and the closure of the Bute Docks, it now sees only passenger services, and is regarded as a branch from the line through to Cardiff Central.

At privatisation in 1995, services were operated by the Cardiff Railway Company, which traded as Valley Lines. This was subsumed by the new Wales and Borders franchise in 2001, which was subsequently awarded to Arriva in December 2003 and operates as Arriva Trains Wales. The December 2005 timetable introduced a further increase in services to 4 trains per hour 18 hours a day, and even a Sunday service for the first time (further improved in June 2006 to offer the same 4 trains per hour service from 11am to 4pm). In December 2005, Arriva employed a single car Class 153 to "shuttle" along the Butetown Line, upgrading from the 2 car Class 143 'Pacers' used for the service. Since then, the service frequency has been increased even more - there are now 5 trains per hour on the line every day of the week, which equates to one train every 12 minutes.

In July 2006 the service was due to be provided by a 1950s British Rail Class 121 "Bubble car" DMU. The unit finally entered service in 17 August 2006, only to be withdrawn for repairs two days later. The unit then re-entered service on 14 September 2006.

Passenger volume
Below is the passenger volume from the year beginning April 2002 to the year beginning April 2010. Comparing the two years, Cardiff Queen Street's usage has increased by 30% whilst Cardiff Bay has increased 323%.

Electrification of the Line
On 16th July 2012 plans to electrify the line were announced by the Government as part of a £9.4bn package of investment of the railways in England and Wales.

The announcement was made as an extension of the electrification of the South Wales Main Line from Cardiff to Swansea and the electrification of the south Wales Valley Lines at a total cost of £350 million. The investment will require new trains and should result in reduced journeys times and a cheaper to maintain network. It is thought to start between 2014 and 2019.