Car park charges at Oxford's park-and-ride centres are set to be scrapped as part of a radical package of measures to combat chronic congestion.

The five sites ringing Oxford will be enlarged and improved to try to persuade motorists not to drive cars into the city centre.

And a multi-million pound package of transport improvements will also include the use of variable message signs on the main approach routes to the Oxford ring road, see map, giving up-to-date information about roadworks, car parking and congestion.

They are also likely to be placed at key points on the A34, if the Highways Agency agrees.

The signs could be in use early as next year. More than half the £440,000 cost will be paid by the developers of the Westgate Shopping Centre extension.

The park-and-ride shake-up comes after visitors to the city said they were baffled by being charged to park at some sites but not at others.

At present, motorists must pay £1 to park at the Redbridge, Seacourt and Pear Tree sites, which are run by Oxford City Council, while those parking at Thornhill and Water Eaton, which are run by Oxfordshire County Council, do so for free.

Passengers must pay a bus fare into the city from all five sites.

The city council is preparing to hand over the running of its sites to County Hall, which will scrap parking fees.

Both projects are part of the county council's £80m Access to Oxford scheme, which was given the green light by the Government last year, and includes plans to expand Oxford railway station, with a new bay platform built on part of the station car park on the southern side of Botley Road. Network Rail hopes to carry out this work in 2010-11.

Money is also being made available to improve access to the city from the north and south, with bus lanes proposed on the Hinksey Hill slip road, to speed up buses between Oxford and Abingdon.

Ian Hudspeth, the county council's cabinet member for transport, said: "Our policy is for free parking at park-and-rides, to enable people to get out of cars on to buses, without them having to fiddle around looking for change.

"We want to encourage people to use buses. We're also conscious of complaints from visitors to the city who have ended up with fines for £100 for not realising there is a park-and-ride charge."