The speed bump stayed there for about six hours - until police moved it at 11.30am.
Police said the speed bump was "unauthorised" and the matter was referred to Whanganui District Council.
The suburban street neighbours Castlecliff Domain, where children often play unattended at the playground.
Residents say kids cross the road at the curb closest to the playground, which sits in a dip in the road. At points the dip is not visible to motorists traveling in both directions.
Another resident told the Chronicle that cars drove down the road at 90-100km/h "every bloody night."
The speed limit on the street is 50km/h.
Derek Payne, a resident on the street for the last three years, says he has approached the council multiple times during his time on the street.
"It's only a matter of time before someone gets bowled here," he said.
Whanganui District Council was contacted for comment.