One of the main roads out of Lyttelton closed since the February earthquake is so dangerous it may never be reopened.
With each aftershock, large boulders have fallen onto to the Lyttelton side of Evans Pass on Sumner Road - an important link for trucks coming from the port.
Port chief executive Peter Davie says about 150 trucks with oversized or explosive goods need to use the road daily.
Since February, some trucks have gone through the Lyttelton Tunnel which has to be shut off to traffic.
Mr Davie says if Evans Pass does not reopen, the port will need to look at alternatives such as Dyers or Gebbies passes which would take twice as long and be much more costly.
The Christchurch City Council is looking at feasible ways to make the road safe, but say while there is seismic activity it is likely to remain closed.