Yellow no parking lines have been painted on a section of London St to address safety issues caused by parked cars.
The parking ban has been put in place on either side of the road near the BP petrol station.
"It was a safety issue as cars were parking either side of and across from a petrol station which made site visibility and entering and exiting the service station difficult," NZ Transport Agency (NZTA) regional transport systems manager Ross I'Anson said.
"We were planning to require the installation of the no-stopping lines due to the proposed subdivision of the land behind the BP for housing, as the traffic volumes at the accesses would become quite high."
Whanganui District Council and residents had also raised the issue with NZTA.