Eight children suffered life-threatening injuries, with two students needing to have arms and hands amputated. 

Mr Stanley was also hospitalised with a broken ankle. 

Gleeson, 50, was charged with 11 offences including four counts of dangerous driving causing serious injury.

He faced Melbourne Magistrates Court on Monday for the start of a two-day committal hearing.

Mr Stanley gave more than two hours of evidence, telling the court he had his indicator on for about 150 metres before the crash site.

The bus driver also said he was either stopped or "inching" when he reached the intersection of Exford and Murphys roads. 

But David Woods, another motorist who was two cars behind Mr Gleeson's truck, told the court he did not see the bus' brakes or indicator lights on. 

Mr Woods said he had a clear view ahead of him and the bus did not slow down before it suddenly took a sharp right-hand turn.

When questioned by Gleeson's barrister James Anderson, Mr Stanley maintained he did indicate and slow down before reaching the intersection. 

He told the court he didn't hear Gleeson's truck braking but the school students were talking loudly and singing inside the bus. 

Mr Stanley also maintained he was wearing a seatbelt before the crash and he believed all of the children had been as well. 

Gleeson, who is on bail, told police he hit the brakes as soon as he saw the bus' brake lights on but he didn't have enough time to avoid the collision. 

He said he noticed flashes of sunlight coming through the trees on his right-hand side in the lead-up to the crash. 

The hearing continues.