Lisa Feeney is taking the dramatic form of protest at Rath Lugh in County Meath, where a motorway connecting the county with Dublin is being constructed.
Building was suspended yesterday amid fears that machinery would collapse soil on top of Ms Feeney and into the tunnel that was burrowed by a group of around 20 protestors.
‘Squeak’, as her friends call her, has chained herself to a car jack holding up the tunnel, meaning that it will collapse on top of her and kill her if any attempts are made to rescue her.
Supporter Debbie Reilly said: “Squeak is chained to a car jack which is supporting the roof of the tunnel above her head.”
The area is ventilated by a wind-powered fan and protesters claim Ms Feeney has enough food and water to sustain her for several weeks.
Campaigners want the M3 motorway rerouted around the Rath Lugh monument — an ancient fort beside the 2,000-year-old Hill of Tara.
But the National Roads Authority (NRA) claimed the protesters may be damaging the protected area by digging deep tunnels into the ground.
“The contractor is well within his right to take responsibility for safety in the area and to request the protesters to calmly leave,” said spokesman Sean O’Neill.
NRA officials brought in satellite technology to pinpoint exactly where the lone protester is located.
Local independent councillor Philip Cantwell said more attention should be paid to the woman’s safety.
“There is a young woman down a tunnel and I have been asking gardaí, where is there a doctor? I’ve been told, no, there’s two safety people there. The two safety people walked away when I asked could I check their qualifications.”
He added: “Bearing in mind the first items in the rescue of a young person would be a stretcher, breathing equipment, oxygen and so on, there’s no sign of that here. I am seriously concerned how this young girl can be protected in the event of a collapse of this tunnel. It seems to me they’re more intent on removal of the protestors rather than the safety of the protestors. I’m seriously concerned about this and the gardaí have turned their back on me when I ask those questions.”
Up to 30 protesters have been living on the site for several months in six tents with wind-powered electricity and shower facilities.
On Thursday Rath Lugh Direct Action Camp failed in its bid to seek a High Court injunction to stop the works by the NRA on the M3 in the vicinity of Rath Lugh.