The road where a police officer was dragged to his death behind a car was a "very narrow country lane" with limited visibility, a court has heard.
Andrew Harper suffered "catastrophic" injuries as he was pulled along near Sulhamstead, Berkshire, in August.
Collision reconstruction expert Simon Hall told the Old Bailey the lane was a "minor country road" made up of granite chippings.
Henry Long, 18, and two 17-year-old boys deny murder.
The court has heard how PC Harper, who was from Wallingford, Oxfordshire, responded to a report of a stolen quad bike on 15 August last year.
A strap trailing behind a Seat Toledo got "lassoed" around his ankles as it accelerated away and he was dragged for about a mile.
Mr Hall told the court the road was about 3.4m (11.2ft) wide.
He said: “It is a very narrow country lane.”
Brian Altman QC, prosecuting, asked him whether it was possible to drive at the 60mph speed limit, to which Mr Hall replied: "You could drive it, but I wouldn’t advise it."
He added: "Certainly on the bendy sections, it would be very difficult.
"On the corners you couldn’t see if anything was coming the other way."
On Thursday two jurors in the trial were discharged because they were self-isolating.
One of them developed a fever and another was self-isolating because her son was showing coronavirus symptoms.
Mr Long, from Mortimer, has admitted manslaughter and conspiracy to steal a quad bike.
The two 17-year-olds, who cannot be named due to their age, pleaded guilty to conspiracy to steal a quad bike. The pair also deny manslaughter.
The trial continues.