Campaigners fighting to preserve a 4,000-year-old archaeological find in Herefordshire say they are facing a race against time.
Experts have said the newly-uncovered Rotherwas Ribbon could be as important as Stonehenge.
Herefordshire Council said a protective shield will be built over the site to save it for future generations and the road will then be built over it.
English Heritage inspectors visited the site, also known as the Dinedor Serpent, on Monday.
They said the site was "very fragile". If they decide the 197ft-long (60m) ribbon of stones is worthy of ancient monument status, it could prevent the road being built.
The £12.5m road was controversial even before the historic trail was discovered.
Nearby residents claimed it was unnecessary and would only cause extra congestion.
The government declined to fund the road, which will link the A49 from Hereford to Ross-on-Wye to an industrial estate at Rotherwas, on three occasions.
The work, which started in April, is now being paid for by a combination of money from regional development agency Advantage West Midlands and housing developers.
Ward councillor Gerald Dawe, who is fighting to save the Ribbon, said: "What we're going to have is a road which no-one wants, going over a part of our history which has a lot of public support.
"This would be a good excuse for the council to stop work on an unpopular road."
Campaigner Rob Hattersley said the site could be turned into a heritage site, attracting tourists to the area.
'Tourism potential'
Mr Hattersley, who runs the campaign's website, said: "Even something like a model of what it would have looked like and an explanation of what it was would be fascinating.
"We've been contacted by historical experts in Salisbury with the experience of having Stonehenge who say that Herefordshire Council needs to listen to the great tourism potential this could bring."
Council chiefs have said the English Heritage inspectors are "completely satisfied" with how they have been handling the situation so far.
However, local campaigners have said recent downpours have led to part of the trail being washed away and say the feature needs more permanent protection before it is too late.
The council's highways and transport spokesman Councillor Brian Wilcox said the road was essential for Herefordshire's economic growth.
He added that he had been contacted by businesses threatening to pull out of the area unless the plans went ahead.
He said: "It is an essential provision. We need it to guarantee extra economic development in this area, and we have the backing of major bodies like Advantage West Midlands who can see how vital it is."
The council is producing a CD-Rom of the site to show the feature from all angles so it can be kept on record and to show future generations in case the road-building work goes ahead.
It is also offering escorted trips around the site next week.
'Money back'
BBC Radio Hereford and Worcester have said the topic has prompted the biggest ever response to a local story.
More than 200 people have contacted the area's BBC Where I Live site to give their views on what should happen to the relic.
A petition calling on Prime Minister Gordon Brown to help save the Rotherwas Ribbon also received more than 210 signatures within its first day.
Does that level of interest show that the Ribbon could be a successful tourist attraction?
Not according to Councillor Wilcox.
"I think they would be asking for their money back," he said.
"We want people to come and have a look for themselves to see the site.
"Often they hear comparisons with Stonehenge and expect it's going to be something similar."
The English Heritage inspectors are expected to deliver their verdicts over the next few weeks.
http://news.bbc.co.uk/2/hi/uk_news/england/hereford/worcs/6289240.stm
Something is not right. This message is just to keep things from messing up down the road