Motorists will have to go slower around town from tomorrow.
Speed limits on more than 100 roads in St Helier are being cut to 20mph.
They are also being lowered in Gorey Village and around Grouville School.
Infrastructure Minister Deputy Kevin Lewis agreed to lower the limits at the request of the parish constables.
The Town Hall says it will stop residents having to put up with people driving too fast down their streets and risking them serious injury.
Signs will be unveiled on Friday, and Honorary and States police officers will be enforcing the new limits.
In other changes, a 30mph limit will be introduced along the east coast road from the existing 20 zone at Ville es Renaud to the 30 sign at the parish boundary with St Clement.
All Jersey's speed limits will be reviewed by the end of this year to ensure consistency across all parishes.
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