Lights along the Avon Ring Road are set to be switched off in a trial aimed at saving money and cutting pollution.

South Gloucestershire Council leaders want to switch off many of the lights along the entire length of the A4174 within its boundary from Filton to the border with Bath and North East Somerset.

Only lights approaching roundabouts and junctions would remain on for safety reasons.

The ring road runs for about 10 miles from the Bristol north fringe to the A4 at Hicks Gate, near Keynsham.

Details of the proposal are still being worked up but it is proposed to turn off a large number of the lights at night, which will slash power bills and carbon dioxide emissions.

South Gloucestershire emitted 1.98 million tonnes of CO2 during 2007 – the most up-to-date figures available.

Heather Goddard, the council's executive member for communities, said: "We have set ourselves ambitious targets to reduce our carbon footprint by three per cent year on year and street lighting energy is a significant contributor to our overall carbon footprint.

"Given that energy prices are projected to keep on rising, we also want to make sure that we keep the cost to the council taxpayer as low as possible.

"It is important to stress that not all lights on the ring road will be switched off. Those on the approaches to major junctions, bends and roundabouts will be left on throughout the night.

"As always, road safety remains a top priority for us so additional inspections will be carried out."

The pilot comes after about two-thirds of street lights were turned off in one South Gloucestershire village as a trial for the district.

Charfield Parish Council agreed more than 170 street lamps could be switched off during the night to save energy and money.

The trial started in the summer, with lights currently going off at about 12.30am and coming back on at 5am.

Latest figures show the electricity bill for the year will be cut by £1,862 a year at current prices, with a saving of 11.5 tonnes of carbon dioxide.

Parish councillor Mike Cheskin said the pilot had been well received generally.

He said: "There appears to be no increase in crime or road accidents as a result of the lights going off so we will carry on."

Mrs Goddard said, depending on the success of the scheme, the authority hoped to roll out the switch-off more widely subject to consultation.