Yellow buses have already begun to be used by some UK education authorities

Education charity, the Sutton Trust, says a school bus network would save �450m by reducing traffic congestion.

The charity has been considering ways to offer an alternative to the extra traffic of the "school run".

It suggests that a safe, pupil-only service would be attractive to parents who now drive their children to school.

The Sutton Trust commissioned research which suggests that a subsidised school bus network would bring substantial financial benefits for the wider economy.

Traffic jams

It says that a subsidy of about �80m a year, with a charge to parents of 50p per trip, would generate savings that were worth two and a half times these costs.

These financial benefits, the survey says, would come through savings in time and running costs which would follow reducing traffic jams when children are being taken to and from school.

There have also been claims that there would be wider social benefits from a school bus network, such as cutting truancy and providing safe access to schools across cities.

"To the Sutton Trust, which was set up to help non-privileged children, the most significant benefit is the effect that school bussing would have on social inclusion," said the trust's chairman, Sir Peter Lampl.

"Theoretically, all parents can choose where they want their children to go to school but in reality that's a myth.

Walking bus

"More affluent parents have a choice because they have the wherewithal to get their children to the school of their choice. Less affluent parents don't and school buses would also give them a choice," he said.

Reducing the number of pupils being driven to school has been a target for several local and national initiatives, with concerns that, apart from causing traffic congestion, the school run is damaging children's health.

In response there have been schemes to encourage children to walk to school, including "walking buses", where groups of supervised youngsters are taken to and from school.