There will be delays and for quite a long time.

But if all goes well the months of delays caused by work at Junction 15 on the M4 will be worth it - as traffic should then find the junction much easier to negotiate.

Work by contractors will begin at the roundabout linking the M4, the A419 and the Marlborough Road in September.

And the £9.5m project will take between 15 to 18 months.

Coun Gary Sumner is the council's cabinet member for strategic planning.

He said: "We are trying to future-proof the junction and increase it's capacity and make it easier for those who use it."

One key part of the scheme is to create a protected left turn lane for those cars heading south on the A419 and then onto the eastbound carriageway of the M4 to London.

Coun Sumner said: "All those cars heading towards London will just be able to carry on, safely, and won't have to get involved with the rest of the roundabout.

"That's one of the major pinch points, if you listen to BBC Wiltshire in the morning it says it's a 10 minute queue, or a 15minute queue.

It's rarely at a standstill, it's always moving, just incredibly slowly - and that's just caused by the sheer weight of traffic heading onto the motorway, and being slowed up by trying to get onto the roundabout."

With London bound traffic safely in a third lane and able to avoid stopping, that should also allow more capacity for traffic from the dual carriageway heading south or west.

There should also be improvements for traffic heading north from the direction of Marlborough.

Coun Sumner said: "Often there are long delays backing up towards Chiseldon. When this is complete, with partial signalisation, Highways England will be able to hold traffic coming off the motorway at the line, and allow the traffic form the south more time to clear.

"We'll be taking measures to prevent people checking their satnav and seeing there's a route though Badbury or Liddington and making the lives of residents more painful during the period of the works."

The upgrade to the junction is a condition of the permission for the Badbury Park developments - the money comes from a £5m grant from central government and £4.5m in Section 106 contributions from the developers of Badbury Park.

Coun Sumner said: "We're not spending any our our council tax on this - there will be delays but I hope people see there will be benefits in the end."