Earth movers have arrived to start work on a £50m bypass but protesters chained to a machine are holding up operations.
Protesters have pledged to lie down in front of the bulldozers
About 10 demonstrators gathered on Wednesday at Linslade, Beds, to protest against the five-mile route from Stoke Hammond, Bucks.
Specialist protest removal officer, PC Steve Lock examined the chains attached to the women's necks while officers decided on the action to take.
Some residents say the road is essential for the safety of the area.
On Wednesday, the anti-bypass group, which feature supporters of Friends of the Earth and newly founded anti-road alliance Road Block, said they feared more housing will be built in the area as a result of the road being constructed.
At about 1030 GMT, a team of 10 workers arrived to fell trees at the site.
They were met by protesters brandishing banners, who blocked their way by linking arms across the track.
A digger parked at the site was also started up but in a bid to stop it moving, one protester climbed on board while another stood in front of it.
One of them, Victoria Harvey, of South Bedfordshire Friends of the Earth, said: "I have no desire to get arrested but to do this is just criminal."
Protesters say that the proposed bypass will not solve local congestion and will endanger wildlife, such as bats.
But Mel D'Agostino, a mother from Stoke Hammond, criticised protesters trying to hamper the development of a major new bypass.
She said her village had gradually been turned into a motorway to Milton Keynes and two years ago, her son was knocked down by a car on the busy stretch.