The Welsh Government's Deputy Minister for Climate Change defended the policy while speaking with ITV's Sharp End.
Support for the new 20mph speed limit in built-up areas "will rise", the Welsh Government's Deputy Minister for Climate Change has claimed.
It comes as a poll for ITV Wales reveals almost two-thirds of people are against the change.
From 17 September, the default speed limit for most 30mph roads will be reduced to 20mph.
Lee Waters MS, who is responsible for transport in Wales, says evidence from other countries who have adopted the policy shows support lowers in the lead-up to the change, but then grows afterwards.
Speaking with ITV's Sharp End, Mr Waters said: "What we've expected to see is that the closer you get to implementation, the support drops.
"We've seen that in London with the congestion charge. That's pretty typical according to the academic research.
"Our tracking shows support is around 50%, so this poll may be an outlier, but we're pretty confident that, as people get used to it, support will rise."
The poll found just 31% support the reduction in speed limits while 66% oppose the policy.
The Welsh Government say that reduction will make the country a safer and greener place to live but opponents argue that the costs of the scheme greatly outweigh the benefits.
The 20mph limit will be in place on what are called 'restricted' roads. These are roads in built-up areas, where there is high pedestrian activity.
The Highway Code, states these types of roads will have streetlights spaced no more than 200 yards apart.
That means there won't necessarily be a 20mph road sign - you should assume a road that used to be 30mph is now 20mph.The policy has faced a large amount of criticism, including from Mr Waters' predecessor, former Welsh Government Economy and Transport Minister Ken Skates MS.
Mr Skates, who represents Clwyd South in the Senedd, stepped back from government in 2021.
He told Sharp End: "I think if there is a fault in the policy, it's that there hasn't been enough citizen involvement.
"All of the evidence shows that if you are to have successful 20mph areas, you have to have community buy-in and support.
"You have to have support. For me, that means community involvement in determining what roads are 20mph."
The Welsh Conservatives claim the government's own research shows the Welsh economy will be hit to the tune of £9 billion because of the policy.
The Senedd's official opposition is calling on the implementation of the policy to be scrapped and plan to force a vote in the Welsh Parliament this week.
Welsh Conservative Shadow Minister for Transport, Natasha Asghar MS, said: “Labour’s 20mph speed limits will have a detrimental impact on our economy, emergency services, and the livelihoods of the people in Wales.
"That’s why in the Senedd this week, the Welsh Conservatives are forcing a final vote on the issue, telling the Labour Government to not go ahead with this ludicrous and dangerous policy.
“Now is the time for Labour to put their extreme ideology and mass confusion to one side and scrap barmy blanket 20mph speed limits.”
Speaking at a press conference on Monday, First Minster Mark Drakeford said: “We will invest around £32m in one off expenditure. That’ll save £92m every year in the NHS.”
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