Human Error The Reason For SMRT Train Leaving AMK Station With Door Open

If you are late to the show train, we’ve got your back, for there has since been an update on “MRT Station Manager Suspended After MRT Leave AMK Station With One Door Open”.

Lest you are unaware, a packed train had moved off from Ang Mo Kio MRT with one of its cabin door open, on Monday, 11 March.

Was on the train and this happened,luckily nobody was hurt,do something about this @SMRT_Singapore pic.twitter.com/QrvHGR9C6n

— Hady Matynn (@Hady_Matynn) March 11, 2019

Reports indicated that a station manager was onboard the packed train attending to a door fault.

Preliminary Findings

The preliminary investigation revealed that the station manager “had “made an error” that allowed the train to move with a door still open”, and he was swiftly suspended from work on Monday while the train was immediately pulled from service.

My colleague, BH, was understandably upset at what he perceived to be a finger-pointing culture.

But being the cool-headed writer of us two, I managed to get him to stay his pen until there is further news on the saga.

And there are.

An Update: Confirm Plus Chop Human Error

Jumping swiftly onto the bandwagon train, ST reported a follow-up piece on the incident yesterday, 14 March.

What might have been suspicions previously had become a a cold-hard fact for SMRT Trains chief executive Lee Ling Wee, in response to ST query, said:

“The station manager made an error in bypassing the train door interlocking system before the train door was closed. This allowed the train to move off. We are strengthening our procedures to prevent a reoccurrence of such nature. Safety is our top priority.”

According to the report, “MRT trains are designed in such a way that when any one door is not closed properly, the train cannot move off.”

“This is because the electrical circuitry of the doors is interlocked with an electrical system that controls the train propulsion system. But if a door’s electrical circuitry is isolated from the train propulsion system, the train can move when the door is open. Technical faults or human error can also lead to a train moving when a carriage door is open, as it did on Monday.”

One former veteran SMRT operations stuff member was quoted as saying: ” “When there’s a problem with one of the doors, the train will not be able to move. Someone will need to activate a door bypass switch and withdraw the train from service.”

All of which brings me to…

Human Error, Procedural Lapse, or Both

—being slightly confused.

In assessing the technicalities, some conclusions were observed.

1: Trains are not supposed to move when a door is open.

2: This is due to the fact that the “electrical circuitry of the doors is interlocked with an electrical system that controls the train propulsion system”.

3: Essentially a fail-safe, right?

But, because there’s always a but.

4: When there’s a door error, someone -and in the case, the station manager- will need to activate a door bypass switch and withdraw the train from service.

Which technically means that the fail-safe has a bypass, for to withdraw a train from service would mean that it has to move, no?

It seems to be that while there was a “human error” involved, the procedures involved might not have been robust or comprehensive enough to ensure that the bypass was also fool-proof.

Should Not But Did Happen

As Singapore Institute of Technology Associate Professor Andrew Ng said: ” Based on the interlocking principles, the train should not (emphasis mine) move until all doors are closed and locked. However, the operator can intervene and override the interlocking, causing the train to move.”

And coming straight for the horse’s mouth for which SMRT Trains chief executive Lee Ling Wee said: “We are strengthening our procedures to prevent a reoccurrence of such nature”, it does seem to me that there’s more at play than just human error.

If part of the station’s manager job was to override interlocking, should there not have been a fail-safe, system-wise, to that ensure that interlocking can only take place if the train’s propulsion system was disengaged or something along the likes?

Then again, I’m no engineer nor even a train expert (I take buses); I’m just a lowly Goody Feed minion writer.