SINGAPORE - An 86-year-old woman who died in November 2014 after she was struck by a school bus in Marsiling Lane had been collecting recyclable items such as cardboard and cans as "a pastime" and "exercise", a coroner's court heard on Friday.

Madam Ching Guan Eng was pushing her trolley across the road towards the parked bus, when she probably encroached onto its path just as it was moving off.

And the driver might have been unaware that she was in his blind spot on the front right side of his bus, State Coroner Marvin Bay said.

Madam Ching was trapped underneath the vehicle and dragged for a short distance. She died on the spot shortly after the accident.

The coroner found her death to be the result of "a most unfortunate traffic misadventure".

The inquiry heard that bus driver Oh Chin Chai, 59, had parked his vehicle, used to ferry school children and factory workers, along the left lane of the two-lane road on the morning of Nov 12, 2014.

Before driving off at about 8.40am, he had checked his side mirrors and the blind spot mirror.

But as he started to drive off, he felt an impact from under his bus, and sensed it vibrating.

A passer-by shouted at him to stop, and he did.

Getting out, he saw the trolley trapped under the front tyres.

He was shocked to see Madam Ching lying motionless, pinned under the rear right tyre.

She was pronounced dead at about 9.20am, after being extricated by rescue officers.

A forensic scientist who conducted a scene reconstruction, to determine the fields of view and blind zones of the bus, found a blind zone spanning a section of the front right side of the bus.

If Madam Ching, who was 1.47m tall, was within that zone, the driver was unlikely to have seen her. And if she had been close to the bus, at a distance of between 44cm and 93cm from the front, the driver would not have been able to see her from his seat, even through the mirrors.

Police investigation officer Nor Affendy Jaffar told the court Madam Ching's family said she had been collecting items as "exercise" for about three years. One of her sons had also told the inquiry that she was in good health, not in any financial difficulty, and had taken to collecting recyclables as a pastime.

Oh had been charged with causing death by negligence, but was granted a discharge not amounting to an acquittal last year.

His lawyer, Mr Kalidass Murugaiyan, who sat in at the inquiry, said he would be asking for the charge to be dropped, in light of the coroner's findings.

His client's driving licence he added, is still with the Traffic Police, and he has been unemployed since the accident.