Traffic is being diverted onto the B721 road at times until Monday to allow the work to take place on a 7km stretch between Kirtle Water overbridge and a lay-by near Rigg and additional patching to the north and west of Annan.
Long queues of traffic, more than a mile long at times, built up on the B721 to the west of Annan on Saturday morning as repair work began at the western end of the by-pass.
Scotland TranServ was carrying out the works on behalf of Transport Scotland, and contract director Gordon Wilson said: “This essential maintenance scheme is vital to ensuring we prolong the lifespan of the road surface benefiting road users using the A75.”
He added: “We are doing everything we can do minimise disruption by carrying these works out over the weekend however we would advise motorists to plan ahead and leave plenty of time for their journeys.”
Road signs on the western approach to Annan have been warning of the work for some time.
And to ensure the safety of motorists and roadworkers alike, Scotland TranServ say the the works will be carried out with closures continuing until the road reopens at 6 am on Monday.
The diversionary route saw most traffic from west leave the A75 just before Annan, go onto the B721, and then rejoin the A75 just after Rigg and likewise westbound traffic leave the by-pass just west of Gretna.
Access for local traffic is allowed on the A75 on either side of the stretches which are closed for resurfacing.