KiwiRail says it fears for the safety of children if they continue to jump off both moving trains and from a rail bridge into the Waikato River at Ngaruawahia.
The concerns come after footage emerged on Facebook showing a young boy jumping off a moving train and into the river on Sunday.
David Gordon, KiwiRail general manager of asset management, says he worries about the consequences for the children if their antics go wrong.
"You've got a group of kids who are going to be daredevils," Mr Gordon told Fairfax.
"They are not really considering what the implications are for them, and I think more for their families than anything, if one of them gets hurt."
Mr Gordon says the river jumping issue is an "intractable problem".
"We've talked to the council about what you can do and we've talked to the police about it. It is just seemingly an intractable problem."
Children blocking bridge
Hamilton man Simon Howe, who travelled to Ngaruawahia for a swim on Sunday, recorded the boy jumping off a train moving across the bridge that runs parallel to Great South Road.
He told 1 NEWS the train in the video was the fourth that day to cross the Ngaruawahia rail bridge, which is notorious for people jumping off and into the river.
Mr Howe said the train had to stop before moving onto the bridge because more than 10 kids were on it, waiting to jump off.
The train then started moving at a slow pace.
He posted the video it to the Kiwi Az Bro Facebook page. He then posted another video, of police officers arriving at the bridge looking for people jumping off it.
In the video, one boy is seen lying dead-still on the train bridge's railing, as two police officers walk across the bridge beneath him.
Police confirmed to 1 NEWS NOW they were called to the bridge on Sunday over a group of kids "stopping trains and throwing rocks at trains".
The children were moved along but no one was arrested.