Due to Dorset county council and whoever else is involved regarding getting the traffic through to the Olympic sailing in Weymouth in 2012 they are in their wisdom going to dismantle the major six exit Roundabout at Canford bottom Wimborne, the one at the end of the bypass just before Merley.
We have been warned that work starts in April just in time for the holiday rush so that they can cause major disruption right through the summer. They are intending to replace the six exit roundabout with traffic lights on every junction, doesnt bear thinking about does it. Normal summers queued up on the A31 in our area, especially on fridays and saturdays and to a lesser extent every other day must bring horrible memories back to people who love to come to dorset for weekends and holidays. We have to live and work and negotiate all this so we have no choice, Im dreading it.
Still they have to ensure that the Olympics two weeks goes off without problems, stuff the natives.
Do yourselves a favour if your travelling from the smoke or indeed anywhere up north this summer approach Bournemouth and Poole from a different angle and forget the M3, M27, A31. There are lots of ways to do it by just studying the map of a quiet evening it will save you bundles of bad temperedness on the day.
From the London area hit out across the A303 or A30 and head for Andover and Salisbury and then on to say Shaftesbury and then head south using Blandford. Lovely countryside on the way and you'll end up crossing over the A31 and into Poole the back way away from everybody else.
If your coming down from up north come down the M5 after Brum and head off towards Warminster or Bath and then down through Sherborne or Yeovil and in the back way once again. Easy peasy and you'll see countryside you never knew existed plus you wont tick off the locals who have to work through it all. Enjoy your holidays
So you can see what a pig this summer is going to be. We're going to have to get up in the middle of the night if we want to go anywhere. Its a crying shame the Council hadnt built a flyover instead of that roundabout when they had the chance and also built the dual carriageway ( possibly M27 ext) that they once intended all the way from Ringwood to Dorchester. They got as far as Bere Regis with the dual section only to run out of money. All the Poole, Dorchester and Wemouth traffic converges at wimborne suddenly up one carriageway. 
all the way down as far as Woodhenge. It joins on to the road just north of the Amesbury roundabout with the A303. Turn right onto A303. Turn right as if you're going to the Stones (Devizes) and then left past them to get back to the roundabout with the A303 again (misses out a lot of the single carriageway traffic). Go straight over the roundabout towards Salisbury & Wilton, turning right when signposted for Wilton. At Wilton roundabout, turn left and then right towards the Salisbury Racecourse. At junction turn left and at end of road right onto the Blandford Road. At roundabout after the dual-carriageway turn left towards ? Oh this is getting too complicated. I know the route like the back of my hand. Lovely B roads and not too much traffic except when you hit the A roads, mainly the A303. You come in to Wimborne Minster from the north. If you follow the road into Wimborne, rather than following the signs around the edge of the town) and use the flyover you should be able to come back down to the Merley roundabout without touching the A31. 