Rail network manager Ontrack is urging sightseers wanting to catch a glimpse of the recreation of historic steam train journey the Parliamentary Special to stay clear of the tracks.
The train, which left Wellington on Wednesday morning, is marking the 100th anniversary of the first train journey along the North Island's main trunk line.
Ontrack chief executive William Peet says he understands the train is attracting enormous interest, but it is illegal to trespass on to tracks and he is urging people to use safe vantage points.
The train is scheduled to arrive at Britomart station in Auckland on Friday afternoon.
The 1908 Parliament Special steamed out of the Wellington Railway Station on 7 August carrying 200 passengers, including 44 parliamentarians.
The 2008 Parliamentary Special left Wellington Railway Station carrying 180 passengers. Only a few are politicians.
While the original trip took 20 hours, the centenary trip will take three days as the steam locomotive and four wooden carriages stop at towns along the way.