Rail operator SMRT and the Land Transport Authority (LTA) will accelerate a programme to replace timber sleepers on the ageing North-South and East-West lines to improve the resilience of the rail network here.

SMRT aims to change out all 188,000 sleepers on the North South Line by 2015, and on the East West Line by 2016. This may result in extended work hours, said SMRT and LTA during a joint briefing on Tuesday.

The two organisations are also firming up details of a plan to replace the entire third rail system.

A joint team from both organizations provided an update on measures taken nearly one year after a high-profile Committee of Inquiry (COI). Various measures recommended by the COI have been implemented, including new sensors to monitor the condition of the power-supplying third rail in real time.

They said the number of trains withdrawn from service on the North-South and East-West MRT lines has decreased from a monthly average of 59 withdrawals in the first four months of last year to 37 in the same period this year.

Said LTA chief executive Chew Hock Yong: "In the short term, LTA worked with SMRT to take some immediate steps to improve rail reliability... As these measures are progressively rolled out in the coming years, we hope to see further improvements so that we can serve commuters better."