The former bus driver who negligently caused the death of the wife of a university professor was on Monday jailed for three weeks and banned from driving for five years.

Chan Mun Hing, 48, failed to give way to Madam Zhang Huirui, 42, when turning his bus left at the junction of Clementi Avenue 3 and Commonwealth Avenue West on the morning of April 23 last year. The traffic lights for both parties were green at the time.

The wife of National University of Singapore Associate Professor Gong Jiangbin was pinned under the front wheel of the SBS double-decker bus and dragged 10.2m before it came to a stop.

She suffered severe injuries, including skeletal fractures, and was pronounced dead at the scene.

In deciding on Chan's punishment, District Judge Wong Choon Ning considered video footage from the bus that showed Chan had started to make the turn even though pedestrians could still be seen crossing from the other side.

This, the judge said, contradicted defence lawyer Lim Hin Chye's argument that Chan had only started to move the bus when he saw the coast was clear.

The lawyer had asked for a jail term of shorter than a week, saying that Chan was supposed to have a day off that day, but opted to work to supplement his income and that could have resulted in his lack of concentration.

Calling for a term of at least two weeks, Deputy Public Prosecutor Allison Phua maintained that Chan was driving a heavy vehicle and the accident occured when the housewife had the right of way.

She added that the video footage showed Madam Zhang had crossed a significant portion of the road before being hit.

The maximum penalty for causing death by a negligent act is a jail term of two years and a fine.