The service frequency is approximately one train per hour in each direction, every day.
During weekday rush hours, day time and early evenings, average service frequency is 5-7 minutes.
This forms a service frequency of approximately 2.5 minutes through central London, with 21 trains per hour.
Originally, the system routes, prices and service frequency remained the same.
In December 2009, service frequency was increased to half hourly at peak times.
The service frequency was increased to 4 trains per hour in January 2011.
During day time ferry service frequency is 45 minutes apart.
This measure remained in effect until the service frequency had sufficiently increased.
Adjust service frequency on Sundays to operate every 20 minutes.
Three 8-car sets (21871 to 21873) were introduced from 25 March 1997 to cope with an increased service frequency.