Eight children fell through gaps between trains and train platforms in Perth last year, an unexplained spike in such incidents that has led to new precautions.

The number of such incidents normally hovers at zero or one, to a maximum of three per year, so Transperth, baffled by the spike, has launched its Mind the Gap awareness campaign.

Spokesman David Hynes said the children had somehow managed it despite Perth's network having some of the smallest gaps between train and platform of any system worldwide.

"This number of incidents is a lot for us, but compared to the eastern states where they have nowhere near the same quality in terms of controlling the gap it's small," he said.