An archaeological dig to investigate a medieval causeway before Oxford's £120m flood channel is built will close a key commuter route for up to six weeks.

A section of Old Abingdon Road will be closed for up to six weeks from October 24, with traffic management, to allow archaeological investigations to take place as part of the Oxford Flood Alleviation Scheme.

And Kennington Road, near the junction with Old Abingdon Road, will have traffic lights in place for two days from October 17 to allow the Environment Agency to identify underground service pipelines.

Joanna Larmour, Oxford Flood Alleviation Scheme Director, said: "We know this will cause some minor disruption in the short term.

"We hope people travelling in Oxford will be understanding and see the wider benefits that the Oxford Flood Alleviation Scheme will have for the city in the future."

Part of the Old Abingdon Road is thought to be a continuation of the Grandpont, the route of a medieval causeway with Anglo-Saxon origins.

Environment Agency bosses say the causeway represents an important element in understanding the topography and development of medieval Oxford.

The Grandpont and the culverts under Old Abingdon Road have protected status due to their rarity value.

Part of the Oxford Flood Alleviation Scheme includes building new culverts underneath the road to reduce the current pinch point at Old Abingdon Road, while avoiding a known scheduled ancient monument.

However, it is possible that there are additional medieval culverts and parts of causeway surviving within the structure of the road.

 The EA said it was essential to carry out an archaeological evaluation now to understand whether there are archaeological risks in this location.

This will help to avoid disruption and delay to this area later in the scheme.

Trenches will be dug in the road to locate evidence of the medieval causeway and explore the extent of any remains.

This will take place by peeling away layers of the ground mechanically. Any archaeological features found within the trenches will then be excavated by hand by a specialist.

In August a different section of the Old Abingdon Road was closed by the Oxfordshire County Council to strengthen the highway embankment that supports the A423 Southern Bypass eastbound near the junction with Old Abingdon Road.

The Environment Agency and Oxfordshire County Council were unable to complete the work at the same time as access to Redbridge Hollow would have been blocked.