Preparation work is due to start in September on a key part of Abingdon's new town centre transport strategy (Abits) - converting Stratton Way into a two-way route and turning Stert Street and the High Street into single lanes.

But monitoring of air quality in the town has shown that the new scheme will not bring about the improvements that had been expected.

The county hopes to put new entry points in the Vineyard, Stert Street and Stratton Way. Also included in the first phase will be new entry points and traffic lights at Ock Street and in Bridge Street, near the Crown and Thistle hotel.

Senior transport engineer for Oxfordshire County Council Andy Warren said: "We're aiming for these three elements to be completed by the beginning of December so we can be in and out before the Christmas period, then we can start the main Stratton Way works in early January.

"Our work is still dependent on land negotiations being completed in time to enable us to do the works at the Vineyard- Stert Street-Stratton Way entry point."

The main aim of Abits is to improve the flow of traffic by removing some through-traffic that will travel along a new two-way Stratton Way.

Widening the pavements in parts of Stert Street and High Street and reducing traffic speeds to 20mph is designed to make the town centre more pedestrian-friendly.

There will be eight additional crossing points, new bus waiting areas away from the High Street, seven new disabled parking spaces within 200 metres of the main shopping area, three new taxi bays and delivery bays in Stert Street and High Street.

Abingdon town and district councillor and member of the transport strategy's steering group Roz Smith said: "An autumn start on preliminary work is good news because at last we will be seeing some progress on the key central area scheme. When the major work gets underway early next year there will be some disruption and we must liaise closely with the Chamber of Commerce to help traders."

District and Abingdon town councillor Monica Lovatt said: "The numerous pedestrian crossings will slow traffic still further. I am unhappy at the loss of free parking spaces which enable people to stop for a short time. There are outstanding issues to be resolved -- the traffic flow in lower Bath Street, the exits from the multi-storey car park and yet another set of traffic lights in Stratton Way."

Mrs Lovatt said the dualling of the Marcham Road from the A34 to Nuffield Way had been a great success. The second phase, from Nuffield Way to Colwell Drive, still needed to be done, as did work at the junction of Drayton Road, Ock Street and Marcham Road.

A parliamentary report says that traffic in the country is forecast to grow by 30 per cent over the next 10 years.