Work has begun on upgrading a dangerous stretch of road on the A75 between Dumfries and Annan.
Campaigners have been calling for road improvements for years, following a number of fatal accidents.
In one of those accidents a three-week-old baby boy was killed.
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Sandy Murray, of Police Scotland, was was giving evidence at the trial of a bus driver who denies killing Ryan Baird by dangerous driving.
34-year-old Christopher Peck was involved in a head-on crash with a drunk driver. His funeral has taken place in his hometown, Workington.
The arrests come weeks after a much-publicised series of appeals to mark the 30th anniversary of the 18-year-old's death.