SMRT investigating root cause of recent rail crack incidents

SMRT investigating root cause of recent rail crack incidents
    POSTED: 20 May 2013 5:44 PM
 
SMRT will carry out a full investigation to determine the root cause of the two rail crack incidents that occurred on the North-South Line on April 29 and May 18 this year.

SINGAPORE: SMRT will carry out a full investigation to determine the root cause of the two rail crack incidents that occurred on the North-South Line on April 29 and May 18 this year.

The incidents caused delays for commuters.

SMRT said its preliminary findings revealed that both incidents bore several similarities.

Both rail cracks occurred at rail joints that were welded between old and new rails located on high rails of a curve track.

Both incidents happened on concrete tracks, at locations that were close to the tail wall of the underground stations.

The tail wall refers to the end of the station where the train pulls in.

Both affected rail joints had been welded by the same contractor in June last year and February this year.

SMRT said it will focus on the material, workmanship, stress factors, and welding process in its investigation.

It will send materials used for welding of the two cracked rails for full laboratory tests to determine their content, quality, and condition.

As for workmanship, SMRT will identify, inspect and conduct tests on all rail joints in the system that were welded by the same contractor. This is to determine the integrity of the rail joints.

SMRT will also study the possible stress factors that may have contributed to the rail cracks.

One possible stress could have resulted from a height difference formed between the welded rails.

Additional stress to the rail joints may have been caused by braking forces of passing trains at the tail wall tracks of underground stations.

To ensure that similar incidents do not occur again, SMRT said it will conduct a thorough inspection of all suspected rail joints on the entire network (North-South Line and East-West Line) and will take appropriate remedial actions.

It said this is in addition to its regular patrols and tests carried out on all its tracks to detect rail flaws in order to ensure rail integrity.

SMRT added that train services would not have been allowed to continue if it was assessed that passenger safety may be compromised in any way.

- CNA/fa

- wong chee tat :)