SINGAPORE - A police officer was driving a police van last year when he fell asleep and crashed the vehicle into a concrete barrier along an expressway.

The impact threw his fellow officer in the rear cabin onto the road, resulting in serious injuries.

For causing grievous hurt through negligent driving, Senior Staff Sergeant Yap Choon Lye, 42, was jailed for three weeks on Friday (Oct 5) and disqualified from driving for three years.

Deputy Public Prosecutor Jotham Tay told the court that Yap was driving the police van along the Ayer Rajah Expressway (AYE), in the direction of the Marina Coastal Expressway, when the accident happened on Feb 23 last year.

With him were civilian officer Siti Aishah Abdul Alim in the front passenger seat, and full-time national serviceman Oh Wen Bin in the back.

The trio had been tasked to deliver some items from the Special Operations Command base in Queensway to the Tuas Incineration Plant. They made two trips there, with Yap driving on both occasions.

After they had delivered the items to the plant, they had lunch nearby before leaving at about 3pm.

Yap felt sleepy during the journey and wound down the driver's window to help him stay awake.

Around the Clementi Road exit on the AYE, he closed his eyes for a while, and failed to maintain proper control of the van.

It veered towards the right and collided into the concrete barriers that separated the expressway traffic from some roadworks.

When he realised what was happening, Yap regained control of the vehicle and stopped it on the outermost lane on the right.

Ms Siti, who managed to stop herself from being flung out of the van, hit her head and body on the dashboard, and was taken to the National University Hospital (NUH) for medical attention.

Mr Oh was thrown out of the back cabin and landed on the road. He was taken to NUH semi-comatose, with injuries including traumatic brain injury as well as skull and facial fractures.

In mitigation, defence counsel Nicholas Ngoh said that Yap had felt drowsy at the time of the accident as the air-conditioner in the van was not working properly.

He also said that Yap did not set out to be negligent in his driving, and had been following the speed limit at the time.

"It is also unfortunate that Oh was not wearing a safety belt at the time of the accident, as the police van was not equipped with safety belts for rear passengers," the defence counsel added.

For causing grievous hurt through a negligent act, Yap could have been jailed for up to two years and fined up to $5,000.

A police spokesman said that following Yap's conviction, the Singapore Police Force will commence disciplinary proceedings against him.