Work on a temporary road as part of the high-speed rail HS2 project has been delayed because of "interesting" archaeological finds, according to contractors.
The route is being built near Great Missenden, Buckinghamshire, to try to keep construction traffic off smaller local roads.
Work was due to get under way last month but will now start in early 2019.
HS2 has said the finds could be prehistoric.
The road will connect the A413 Great Missenden roundabout in Buckinghamshire to the north portal of the Chiltern Tunnel.
Widening of two roundabouts on the A413 by Link Road and Frith Hill will also start in January, according to the Local Democracy Reporting Service.
Charlotte Hughes, from engineering contractor, Fusion, said further archaeological works would be carried out to establish if there were any other historic objects.
"We have been putting in trenches - very long, quite shallow pits - to have a look at what might be of interest," she said.
"We have actually come up with some interesting finds.
"We can't yet talk about the nature of what we have found there, as it has got to be researched and investigated by the archaeologists."
A spokesman for HS2 said they will update the community on what has been found, once a study has been completed, but he believed they are prehistoric.
"Archaeological finds such as this are factored into HS2's construction timetable and do not affect delivery of the programme," he said.
Over 200 archaeologists and specialists are working on another HS2 site beside Euston Station in London to remove 45,000 skeletons from a burial site to make way for construction.
A 15.8km (10mile) tunnel will be dug through the Chilterns in 2020, with work expected to be completed by 2023.
It will start just inside the M25 south of junction 17 and come out northwest of South Heath.
The first phase of the £56bn railway is due to open in December 2026, with trains to travel at high speed between London and Birmingham before continuing on the existing West Coast Main Line.