four aspects: the rate of change of the acceleration and deceleration of trains the welding of components' mounting brackets the profile of the track and train wheels suspension system Since the full introduction of automatic train operation (ATO) on the East Rail system in 2003, the rate of change of acceleration and deceleration resulting from ATO driving added stress to the underframe components. To allow a root cause investigation to be carried out, the use of the ATO system was suspended on 15 January 2006, leaving the operation of trains back in the hands of the train drivers, the safety of train operation under the control of the automatic train protection system. This resulted in a decreased frequency (from 24 to 23 trains per hour) and lengthened trip time (increase by 90 seconds to 42.5 minutes). KCRC also temporarily transferred some staff from West Rail to cope with recent maintenance of trains. The Environment, Transport and Works Bureau reprimanded the KCRC for not immediately notifying the Government when it found problems with its East Rail trains in 2005. Secretary for the Bureau Dr. Sarah Liao said she had ordered the KCRC to inspect all its trains, and did not rule out suspending services if there were safety doubts. Dr. Liao ordered the chairman to review the corporation's operations, including its management and overall system, and submit a report. KCRC chairman Michael Tien accepted responsibility for the corporation's poor judgement in not sharing the information with the public in a timely matter. On 21 January 2006, Michael Tien stated that the safety problems of East Rail had been controlled, and the train service was expected to operate as usual, including train service in the Chinese New Year. KCRC East Rail trains reverted to the ATO operation on 6 August 2006, after the investigation confirmed that the ATO system was not a direct cause of the cracking. Platform gaps The wide platform gap at several stations (namely Lo Wu, Tai Wo, University, Kowloon Tong, and Mong Kok East) is a safety concern. The KCRC has visually marked the "Gap Black Spots" on the platforms of those stations and stated that plates will be installed in the gap between the train and station. The platform gap is mainly caused by the curvature of the station and how the train enters the station area. A mechanical gap filler system, which extends the platform edge