SINGAPORE: A joint team of experts from the Land Transport Authority (LTA) and operator SBS Transit will look at more ways to strengthen the overall North East Line (NEL), following recent disruptions.
The cause of the two major breakdowns on the North East Line in August last year and this January were due to corrosion of the bolts supporting the power line.
A joint team of experts from LTA and SBS Transit revealed the findings on Friday during a visit by Transport Minister Lui Tuck Yew to the Sengkang depot.
Plans are underway to make the line more robust by the middle of next year.
Trains on the North East Line receive power from the overhead power line. Components such as U—bolts and Balance Weight Anchor wires help to keep the power line taut and in place.
The power supply gets disrupted should any of the components fail.
And that was what happened in March and August last year as well as January this year —— when either of the components failed.
One common cause of all three incidents was corrosive agents found between the HarbourFront and Outram Park stations.
The March incident was due to chloride from tunnel water seepage which contributed to the failure of the wires, while chloramines were the corrosive agents that caused the failure of the U—bolts in the August and January incidents.
Preliminary tests concluded that chlorine and traces of ammonia were found at the stretch of the tunnel. Further tests will be conducted to locate the source of these corrosive agents.
The joint team, however, believes there is no indication to suggest that this is a system—wide problem.
There are plans to replace the material used for the components —— for example, the bolts within the NEL system will be replaced, and Mr Lui said the type of bolts will be decided on by the end of the year.
Mr Lui stressed: "You want to be able to have more graceful degradation, you want to have time to be able to pick it up, stop the service, do a quick repair so that you can bring up the service safely and as quickly as possible.
"We hope to be able to make a decision on this before the end of the year, on what is the most suitable material, given the environment that we have because you don’t want to change it to something else that will give you different problems.
"So you need to have a proper consultancy, a much deeper understanding of the methodological plus gaseous interactions and then make a decision on what is the most appropriate step or measures that we need to take."
In the meantime, the operator will continue maintaining the system with the old bolts.
SBS Transit has started replacing all the 1,600 U—bolts along the stretch of the tunnel between HarbourFront and Outram Park stations. Half of the bolts have been changed out, while the remaining 800 will be replaced by mid—April this year.
All the Balance Weight Anchor wires within the system will also be replaced with a new material, once the study for this is completed in May this year. The replacement programme will be completed by mid—2014. SBS Transit has been paying for all the replacement work so far.
An independent consultant will also be engaged to conduct a comprehensive review to enhance the maintenance and recovery procedures. The study is also slated for completion by the middle of next year.
Mr Lui said SBS Transit will also work at reducing the number of faulty trains pulled out of service.
To facilitate this, the rail operator will bring in 25 per cent more staff to work on the operations and maintenance of the North East Line and Light Rail Transit, by the end of the year.
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