It has received complaints by the thousands over the years. Now an online petition demanding the upgrading of one of Scotland's most dangerous roads, the A82, has attracted the largest number of signatures ever received since the process was formally launched by the Scottish Parliament.

A total of 5277 people have supported the campaign since it went live less than three weeks ago and it is already the largest e-petition submitted since the system began in 2004.

Campaigners are concerned about the safety of the road, which is the main transport artery linking Glasgow with the west Highlands and islands. Between January 2005 and the end of last year, there were 22 fatal road accidents and more than 450 people were injured in crashes on the road between Tarbet, Fort William and Inverness.

On Monday, there was another to addition to the statistics when two vehicles collided near South Laggan, north-east of Spean Bridge. The occupants of the two cars both suffered serious injuries and were taken to hospital in Fort William.

Brian Murphy, the Highland councillor who chairs the A82 campaign group, said: "The overwhelming support for our petition sends a very clear message to the parliament about the strength of feeling that exists among the people of the west Highlands and islands on the importance of upgrading the A82. They are not prepared to put up with this sub-standard road any longer."

It took five months in 2006 for 4187 people to sign an e-petition calling on ministers to reconsider the Aberdeen West Peripheral Route. The A82 e-petition, which went live on March 6, is part of a new campaign backed by Highlands and Islands Enterprise, Highland Council, Northern Constabulary, the Chamber of Commerce and community representatives.

After Monday's accident, the road was closed to traffic while investigations were carried out and campaigners say that such instances highlight concerns about the economic impact of the A82's safety record.

It has been calculated that if the A82 is not brought up to standard it could cost the Highlands and islands' economy almost £500m a year in the future.

Stewart Stevenson, the Transport Minister, has agreed to meet the A82 campaign group early in May, but is unlikely to give an immediate commitment to upgrading the entire 133 miles to Inverness.

However, campaigners want planned improvements of four crucial sections to be accelerated. It is estimated that it will take £90m to: improve the northern stretch on Loch Lomondside including the removal of the notorious "temporary" traffic lights at Pulpit Rock; build a Crianlarich bypass; build a new road with climbing lane on the Achallader Brae to Loch Tulla stretch and widen the road between Corran and Fort William.

Transport Scotland has said it is already conducting studies on Loch Lomond and Crianlarich and work could start on both in 2010-11, but campaigners want work to begin earlier.

Support for the campaign has poured in from across the world with signatories from as far afield as Russia, Japan, Canada, Australia and New Zealand.

One said: "Having just spent three years in Spain, travelling on their magnificent EU-funded highways, it sickens me to hear of further loss of life and to see the state of the A82.

"Tourists must surely think they have taken a wrong turn when they turn on to the twisty section of the Loch Lomond road, in disbelief that this can be an A-road."