SMRT disruption – Commuters are so lucky

After the biggest train disruption in the history of SMRT, the original suspicion on the root cause of the problem was an ageing train system. And there were recommendations that it was time to replace the train system with a new system and have a fresh new start. A brand new system would likely to be free from breakdowns for the first 20 years. The present system is starting to breakdown after 30 years.

Thankfully  or not thankfully, the team of experts have found the root cause of the disruption. I quote from Business Times, 

‘LTA, SMRT and five overseas experts carried out comprehensive system-wide checks across more than 200 km of train track and components such as the third rail, power cables and the signalling system to identify the root cause of the disruption. They also checked all 141 trains and analysed train logs from the day of the incident.

Their conclusion: a confluence of factors triggered the incident.

In the tunnel between Tanjong Pagar and Raffles Place, water was found dripping onto the third-rail cover near an insulator. Tests on a sample on the cover and on water collected from the tunnel leak found mineral deposits with a high chloride content. The presence of chloride on the insulator, coupled with a wet environment, would have significantly reduced the effectiveness of the insulator.’

Let me put it simply, rain water dripped on the third rail cover near an insulator, or was it over an insulator, and the water contained high level of chloride that caused a power leakage, reducing the effectiveness of the insulator.  And the solution,

‘To minimise the possibility of a similar recurrence, it has started replacing third-rail insulators, starting with those showing signs of electrical resistance weakness. The remaining insulators will be changed under a planned renewal of the third-rail system, to be completed by the first quarter of 2017.’

I confess that I am not an engineer and find it difficult to rationalise the solution to the cause of the problem. There was water seepage, which means either the cover was not covering properly or there was a hole somewhere for water to seep through. If this was an isolated incident, not all the covers were affected, and there was no other seepage of water elsewhere, would it be sufficient to just replace the cover or ensure that the cover is covering the insulator properly to prevent a seepage, or to make sure rain water did not leak into the insulator. Also, how come rain water contained so much chloride or salt equivalent? Normal, natural?

What I don’t understand is that why were there so much salt in the rain water just after a rain? Could it be someone or animal urinated on it? How many pieces were affected? Why not replace the cover at fault? Why the need to change all the insulators if it was the cover that was giving problem? Wasn’t the root cause due to water that contained too much chloride, and if no chloride, even the water would not affect the insulators? Why was it necessary to change all the insulators if the insulators were functioning well without chloride? I heard some comments about weak resistance of the insulators. Are these insulators meant for heavy duty works? A little water or chloride can cause severe system breakdowns?

What is the problem, cover not covering properly, water or chloride and where did the chloride came from? Or was it the insulator that was giving problem? Would it be effective if the source of water is removed or the source of chloride is removed or prevented from contacting the insulators?

Why the need to change all the insulators? I am just asking layman questions. When a switch in the house does not work, you don’t have to change all the switches. If someone spilled water on the switch, you don’t have to change all the switches. I think like a layman and using a layman’s logic. If I want to use power logic or the logic of having a lot of OPM, I can change all the trains too because of some water found with high content of chloride that seeped through a bad cover.