New guidance issued to councils has urged the increased use of 20mph speed zones around schools
More 20mph speed limit zones should be set up around schools and built up areas, new guidance issued to councils in Wales suggests.
The assembly government guidance will also look at crash rates on rural roads to see if limits there should be cut.
Some road safety campaigners want ministers to go further and establish compulsory 20mph zones near schools.
But a group representing motorists said they devalued speed limits and claimed few people obeyed them.
Transport Minister Ieuan Wyn Jones said local speed limits were a "crucial tool" in improving road safety and reducing casualties.
The assembly government is responsible for determining speed limits on motorways and trunk roads, while local authorities set them on the minor road network.
Speed limits play a fundamental role in effective speed management to encourage, help and require road users to adopt appropriate and safe speeds
Transport Minister Ieuan Wyn Jones
"Speed limits play a fundamental role in effective speed management to encourage, help and require road users to adopt appropriate and safe speeds," said Mr Jones.
He said it was important councils and the police worked together in considering any changes to speed limits.
He said there should also be consistency, especially where roads crossed county boundaries.
Mr Jones said increasing the use of 20mph limits across Wales was a commitment in One Wales, the coalition agreement between Labour and Plaid Cymru.
Currently there are 481 20mph limits or zones in Wales which have risen steadily in the recent years after assembly government funding.
Mr Jones said: "Studies have shown that 20mph schemes can improve safety and we would encourage local authorities to consider implementing more of these where appropriate."
The guidelines are being published in advance of a new national road safety strategy.
This will incorporate casualty reduction targets for beyond 2010 and may be accompanied by additional speed management advice.
There's no point in having speed limits that nobody is going to obey - it's altogether nonsensical
Association of British Drivers
Andrew Farina-Childs, a founder of the S20S campaign which has called on the assembly government to force local authorities to establish 20mph limits around all schools, said such a zone was in the process of being established around his local school, Blackwood Comprehensive in Caerphilly county.
Mr Farina-Childs said there was no question that it had proved effective in slowing down traffic.
"It's far safer for the children and the traffic is adhering to the new speed limit," he said.
But the Association of British Drivers claimed 20mph zones "devalued" speed limits.
"There's no point in having speed limits that nobody is going to obey - it's altogether nonsensical," said a spokesman.
"We are adamant that we need to improve the safety of our roads but you don't do that by penalising people for driving above some number on a sign on the side of a road.
"We want to get away from what speed people are driving at and focus on how people are driving."
He said governments should fund more police patrols and introduce stiffer penalties for people driving under the influence of drink or drugs or without insurance.
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