The speed limits on 68 St Saviour roads have been reduced to provide safer routes to school for children and young families.
It follows a public consultation in July 2019, which asked islanders for their feedback on parish speed limits as part of a Road Action Safety Plan.
40 of the roads are down to 30mph and the other 28 are now 20mph zones.
Infrastructure Minister Deputy Kevin Lewis signed a Ministerial Decision to bring the new speed limits into effect.
"Our ongoing review emphasises road safety, with particular focus on reducing speeds within school vicinities, this will help to provide safer routes to school for children and young families. Elsewhere, lower speed limits are intended to enhance the environment for those living nearby.
"I appreciate such changes may take time to get used to, I ask motorists and road users to observe the new signs and familiarise themselves with the changes."
Greve d'Azette (from Harve des Pas to Beach Road) will be reduced from 40 to 20mph.
A full list of the changes can be found here.
The Constable of St Saviour, Sadie Le Sueur-Rennard, hopes this will make islanders feel safer when walking.
"Ensuring the safety of Parishioners and schoolchildren in our community within St Saviour is important to me, that is why I am committed to delivering the Speed Limit Review which primarily focuses on reducing the Speed limit in School areas, precisely 43% of the speed limit changes on Parish roads are within vicinities of schools, Community centres and nurseries.
"The Road Committee’s aim is to encourage parishioners and children to walk to school, promoting a safer environment and a more attractive walking route for children and to make roads safer within schools and urban areas. Reducing speed limits in such areas will help keep children safe."