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.