A POLICE traffic officer from Stourbridge reacted at lightning-fast 0.84 seconds when he suddenly saw the student he knocked down on a pelican crossing, a court heard.

But even that did not give Pc Vaughan Lowe chance to avoid hitting Birmingham City University student Zhang Xuan Wei who was thrown in the air and later died from his injuries, a jury at Warwick Crown Court was told.

Accident investigator Kevin Sweeney, described by the prosecutor as a collision expert, said he had studied the recording from the on-board camera in Pc Lowe's unmarked BMW.

Checking that frame by frame, he established that from the moment 24-year-old Wei could be seen on the crossing on the A34 New Town Row, Birmingham, to the officer trying to take avoiding action was just 0.84 seconds.

Mr Sweeney said the normal reaction time for a driver was one to 1.5 seconds.

And he commented: “I’m not surprised Mr Lowe has responded quicker, but I would not have expected him to have reacted that quick.”

Despite the officer’s fast reaction time, Mr Sweeney said he had calculated the BMW was doing 48 to 50mph when it struck Wei who had dashed onto the crossing as the 'green man' was flashing at around 7pm on April 4 2012.

At the start of the case Mr Reeds told the jury the prosecution’s collision expert had calculated that at that point ‘a crash could not have been avoided at any speed over 26mph'.

But Mr Sweeney did not give that figure in his evidence – and asked by Brian Dean, defending, why he had not done so, Mr Sweeney replied: “There’s a mistake in the distance calculated.”

Mr Dean commented: “A massive mistake."

He put to Mr Sweeney that the speed at which a collision could have been avoided at that point was ‘more likely closer to ten miles an hour'.

And Mr Sweeney accepted: “If that is the calculation your expert has reached.”

Pc Lowe, a traffic officer based at the West Midlands Police traffic unit in Aston, has pleaded not guilty to causing Wei’s death by careless driving.

The trial continues.