Jurors were shown footage of a cyclist’s final seconds before a crash which led to his death in hospital several days later.
They were shown CCTV footage taken from inside the bus driven by Andrew Blyth, who is accused of killing Robert Don, 53, by driving his coach carelessly.
Mr Don was cycling home from visiting his sister when he was briefly filmed by the in-coach CCTV system as Blyth approached and passed him on the A9.
The footage did not show a collision but Blyth told the trial there was “a bang” and he stopped the Parks of Hamilton coach a short distance further down the road.
Footage of the scene taken after Mr Don was removed to hospital showed his bicycle lying at the side of the road and a pool of blood and a single glove nearby.
Blyth told police during an interview after the incident that he had not seen the cyclist who was not wearing a helmet and did not have any high- visibility clothing on.
Police Scotland accident investigator Steve Whittet told the trial: “The driver of the bus could have easily taken evasive action to avoid the pedal cyclist if seen, and reacted to the pedal cyclist in the time available to him.”
However, defence expert Jim Brunton, 58, of the Transport Research Laboratory, told the jury that Mr Don was only visible on the CCTV footage for 1.4 seconds.
“From the first point of possible perception, to disappearing down the side of the bus was 1.4 seconds, which is less than the two seconds reaction time,” Mr Brunton said.
“He would have to see something first to react to it. There is no way of determining reaction time in the given period, but we allow drivers a reaction time of two seconds.”
He told the court that the brake lights on the bus came on 0.4 seconds after the bike disappears out of shot.
The jury was earlier told that Mr Don was found to have sustained a head injury and died in hospital more than a week later.
During his police interview, Blyth said: “I stopped just because of the bang. I did not see him whatsoever.”
The jury was told in an agreed statement that Mr Don had not been wearing a helmet and was not wearing any high visibility clothing. He was wearing a black jacket and blue jeans.
The jury also heard that he had been visiting his sister in Luncarty, and was cycling home to Amulree Court in Perth when he was injured on December 30 2013. He died on January 8 2014.
They heard that the cycle path which runs alongside the A9 Inverness to Perth road was flooded and impassable at the time of the incident.
The trial was told that the bike was found on the pavement at the side of the road along with blood. The coach was being driven at 53mph.
Blyth, of Abbotsford Road, Hamilton, denies causing Robert Don’s death by driving his coach carelessly on the A9 near Inveralmond roundabout on December 30 2013.
The Crown closed its case on Tuesday and the trial, before Sheriff William Wood, continues.