SWINDON Council is to negotiate with the Government for more than £100m to pay for an “essential” extension to Thamesdown Drive to ensure the town’s road network does not grind to a halt.

The Purton -Iffley Relief Road, estimated at between £100m and £120m, would start where Thamesdown Drive ends at Purton Road and would cross the railway to join up to the Barnfield Roundabout, not far from B&Q.

Swindon Council originally secured £17m towards the work through contributions from developers behind Priory Vale , but the previous Government could not commit the rest of the funds. The agreement was re-negotiated in about 2007/8 and £14.5m was agreed instead for other works, including on the Bruce Street Bridges.

Now, as the planned Tadpole Farm and Ridgeway Farm developments threaten to put even more cars on Swindon’s roads, the council has passed a motion to start negotiations with the Department for Transport for the shortfall.

Coun Keith Williams , Swindon Council’s cabinet member for leisure and strategic transport, said: “It’s a case of going back to the department and saying this is a road that’s really important for Swindon.

“It’s a major arterial route that is strategically key and what we need is some commitment or discussion as to how we can actually put this important road link in from the north of Swindon through to the other arterial dual carriageways we have in the town.

“Mead Way is not built for the amount of traffic it’s taking. If we get to the stage – and it’s not far off – where we have to do major road repairs on Mead Way, it’s going to cause a big, big problem for the traffic network in Swindon. The roads start to grind to a halt.

“Across the borough, all councillors of all parties agree this is something that’s quite essential. With a further expansion to the north of Swindon, this is really quite fundamental.”

Coun Williams said despite the importance of the road, it would not appear in the Core Strategy because this key strategic planning document had to be “deliverable”. The relief road was not currently possible because it lacked financial backing.

He said the council would have to look at whether it could commit any money itself – possibly from the remnants of the re-allocated developer contributions, or even developer cash from the Tadpole Farm estate. Coun Rod Bluh , the council leader, said the authority would have to make a strong business case to Government, adding that about £10m was left of the £14.5m re-negotiated from developers.

“We have, as a council, to explore possibilities with Government, recognising that huge sums of money are difficult to find in the current climate and it’s about making sure we present the best business case possible,” he said.

Coun Jim Grant, the Labour group leader, said: “If Tadpole Farm is going to be sustainable as a development then it must have the right infrastructure. The northern relief road and a link to the A419 are essential to both Tadpole Farm and the future economic success of Swindon.”