MRT rail claws are still being dislodged despite being secured with cable ties last December, a Committee of Inquiry (COI) heard on Thursday.
This was revealed by SMRT line manager Loke Kwok Hoong, who took the stand on Day 13 of the public inquiry into the two major train disruptions last December.
Claws form part of a support assembly that holds up the third rail, which in turn supplies power to trains.
Following those incidents, operator SMRT secured all claws on the North-South and East-West lines with cable ties in a bid to prevent them from dropping off.
Committee member Lim Mong King asked Mr Loke if he knew of any claws dropping even after being bound by cable ties last December.
Mr Loke said claws were still dropping.
He added that he was unsure if the cable ties used were capable of holding the claws in place.
'You are using the normal industrial cable tie, not the special type of cable tie,' he said, but did not elaborate.
Mr Loke, 57, was one of five SMRT staff who took the stand on Thursday as the inquiry's focus remained on maintenance issues.
This ranged from how SMRT patrolmen conducted their inspections to the circumstances surrounding a mirror on a multi-function vehicle (MFV) that cracked.
An MFV is used to measure if the third rail is properly aligned and to check the rail structure for internal flaws.
The committee also heard how SMRT has tweaked some of its maintenance procedures and is improving others.
Assistant engineer Hashmy Ridzwan, 51, said the caps covering the third rail claw assembly have been left open since the December incidents. This allows employees to visually check if the claws are loose.
Previously, claws were obscured by caps. This meant staff had to rely on signs of damage or misalignment to the third rail covers.
Mr Wong Then Sin, 51, senior manager of SMRT's Engineering Trains Branch, added that the operator will buy a new MFV that can pinpoint the locations of third rail assemblies with far greater accuracy than its existing one.
SMRT will also transfer its newer Circle Line MFV to service the North-South and East-West lines so staff can use it to gauge the accuracy of the older MFV, he said.
Mr Wong was on the stand for about four hours - the longest any witness has been questioned so far.
State counsel Fu Qi Jing queried him extensively on the MFV and what happened on the early morning of Dec 17 when staff reported that its side mirror had cracked.
Mr Fu noted that there were several occasions before the Dec 17 incident where MFV readings had exceeded the safety tolerance limits between Newton and Orchard stations. On Dec 17, a portion of the third rail had sagged between those two stations. He asked Mr Wong if he was aware of this 'problem area'.
Mr Wong said maintenance staff had been notified, and that his department had conducted a trend analysis study and flagged this area as a problematic one.
This was revealed by SMRT line manager Loke Kwok Hoong, who took the stand on Day 13 of the public inquiry into the two major train disruptions last December.
Claws form part of a support assembly that holds up the third rail, which in turn supplies power to trains.
Following those incidents, operator SMRT secured all claws on the North-South and East-West lines with cable ties in a bid to prevent them from dropping off.
Committee member Lim Mong King asked Mr Loke if he knew of any claws dropping even after being bound by cable ties last December.
Mr Loke said claws were still dropping.
He added that he was unsure if the cable ties used were capable of holding the claws in place.
'You are using the normal industrial cable tie, not the special type of cable tie,' he said, but did not elaborate.
Mr Loke, 57, was one of five SMRT staff who took the stand on Thursday as the inquiry's focus remained on maintenance issues.
This ranged from how SMRT patrolmen conducted their inspections to the circumstances surrounding a mirror on a multi-function vehicle (MFV) that cracked.
An MFV is used to measure if the third rail is properly aligned and to check the rail structure for internal flaws.
The committee also heard how SMRT has tweaked some of its maintenance procedures and is improving others.
Assistant engineer Hashmy Ridzwan, 51, said the caps covering the third rail claw assembly have been left open since the December incidents. This allows employees to visually check if the claws are loose.
Previously, claws were obscured by caps. This meant staff had to rely on signs of damage or misalignment to the third rail covers.
Mr Wong Then Sin, 51, senior manager of SMRT's Engineering Trains Branch, added that the operator will buy a new MFV that can pinpoint the locations of third rail assemblies with far greater accuracy than its existing one.
SMRT will also transfer its newer Circle Line MFV to service the North-South and East-West lines so staff can use it to gauge the accuracy of the older MFV, he said.
Mr Wong was on the stand for about four hours - the longest any witness has been questioned so far.
State counsel Fu Qi Jing queried him extensively on the MFV and what happened on the early morning of Dec 17 when staff reported that its side mirror had cracked.
Mr Fu noted that there were several occasions before the Dec 17 incident where MFV readings had exceeded the safety tolerance limits between Newton and Orchard stations. On Dec 17, a portion of the third rail had sagged between those two stations. He asked Mr Wong if he was aware of this 'problem area'.
Mr Wong said maintenance staff had been notified, and that his department had conducted a trend analysis study and flagged this area as a problematic one.
