Drivers of long buses and trucks are being advised to carry National Train Control's Centre emergency number on them.
It follows a collision between a train and long bus at a level crossing at Paekakariki north of Wellington.
The bus had stopped and the crossing - but it was so long part of it remained over two of the three lines of tracks.
The driver and were six passengers got out moments before the collision with a freight train.
The Transport Accident Investigation Commission says there are at least 251 other rail crossings with similar size issues.