Crash investigators are at the scene and Dumfries and Galloway Police estimate that the road will remain closed until after midday while they attempt to determine exactly what caused the collision.
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Calmer conditions - for now.
The 12.5 hour walkout by 63 GMB members got under way at 6am this morning and will continue until 6.30pm this evening.
37-year-old Graeme Haddon pleaded guilty to the offence which happened in his home village of Lamancha near West Linton at the weekend.