Motorists using the Whanganui River Rd should have noticed an 80km/h speed restriction now in place.
It used to carry the open road 100km/h limit but Whanganui District Council and its iwi liaison committee believe that was too fast for this type of road.
The change has been driven by a number of things, including growing tourist traffic volumes as well as more cyclists completing the Mountains to the Sea cycleway.
The River Rd is generally narrow for much it its length as it winds its way along the banks of the Whanganui River from State Highway 4 north of the city to Pipiriki.
Reducing the speed limit was first raised late last year but at that stage council was talking about a district-wide 80km/h limit on all rural roads. That suggestion has now been deferred at the request of the New Zealand Transport Agency.