The clearing of trees to build the controversial Riederwald Tunnel in Frankfurt is possible in certain areas, according to the federal Autobahn GmbH, although protected beetles have been discovered on site.
An expert report has shown that the spread of the protected Heldbock beetle "is to be expected with reasonable certainty", the federal authority announced on Friday.
However, the places where the beetle can occur can be localized.
Outside of this there is an area that can be cleared without conflict, as the authority explained.
The location of the construction roads will be changed so that they only run there.
This can rule out the possibility that the beetle occurrence would be damaged.
The environmental association BUND and other initiatives had called for the construction of the motorway to stop after specimens of the protected beetle were found in the forest intended for clearing.
The controversial clearing work for the tunnel had already been postponed several times.
The continued construction of the A66 and its connection to the A661 with the planned tunnel have been among the long-running political issues in Frankfurt since the mid-1980s.
At the same time, the authority announced further investigations.
It is said to be about trees that have been identified as suitable for the beetles.
The felling of these trees will not take place in the current period, explained Autobahn GmbH.