Drivers in Plymouth are facing the lowest speed limit in the UK - 10mph.
The Department for Transport pilot scheme in the Morice Town area will be monitored and could be introduced elsewhere in the country.
The new speed limit, reduced from 30 mph, covers nine streets in the city's
Home Zone area, one of nine established nationally in 1998.
Warning signs mark the entrance to the zone, where kerbs have been removed, and chicanes and planted features introduced.
Plymouth City Council project manager Adrian Trim said: "Home Zones could be seen as turning the clock back 50 years to a time when the space outside our homes was considered to be safer, and was shared equally by all road users - a time when communities were more cohesive and neighbourly."
Mother Liz Welford said the traffic situation there was a "nightmare"
before the scheme came into being.
She said: "You had people zooming up and down the streets all hours of the day and night.
"You could not have let the children outside the front door - it was the
garden or nothing."
The streets covered by the 10mph zone are: Charlotte Street, Herbert Street, Balfour Terrace, Keat Street, Boscowan Place, Pentamar Street, Ross Street, Garden Street and Cross Hill.