The company behind a new wind farm will transport the turbines and towers through Newtown, despite the new bypass likely to have been opened just weeks later.
Montgomeryshire AM, Russell George, has criticised the decision, saying they should wait until the bypass opens to avoid delays and more congestion.
The components will be taken to Hendy via the A483 and A489 through Newtown in mid-January, just a matter of weeks before the new Newtown Bypass is due to open.
Powys County Councillors rejected the planning application for a wind farm at Hendy in April 2017 amid objections about the visual impact and the threat to a protected public right of way. This decision was then upheld by the Planning Inspectorate earlier this year.
However, on October 25th, the Welsh Government's Cabinet Secretary for Energy, Planning and Rural Affairs, Lesley Griffiths AM, overruled the Planning Inspectorate, and gave it her approval on the grounds that the seven-turbine wind farm "outweighed negative possible impacts."
Responding to the news that abnormal heavy goods vehicles will be required to travel through the main trunk road in Newtown, Mr George said:
"It is important that you have community support when planning large-scale renewable energy projects so I fully respect the decisions taken by both Powys County Council in 2017 and the Planning Inspectorate for Wales in 2018 to reject this project.
"Despite the evidence and all of the credible opposition to the wind farm application at Hendy, the Welsh Government's Minister for Environment and Rural Affairs has ignored the potential impact to tourism in the area, the damaging effects on the setting of four Scheduled Ancient Monuments and the fact that four of the wind turbines will be built on a protected right of way.
"This is clearly unacceptable and it is a huge concern that bypassing democratic decisions and ignoring local communities is becoming the norm for the Welsh Government.
"For Newtown and the wider area, it would be totally unacceptable for what is an already heavily congested road to have further disruption from abnormal vehicles transporting wind turbine components and other equipment for this wind farm before the new Newtown Bypass is opened.
"This is a rushed effort to construct the wind farm before the end of January so that the developer can receive a financial advantage.
"We are also aware that the developer is not following planning conditions that have been set. It is deeply frustrating when developers and indeed Government think they can ride roughshod over communities."
He added: "I understand that the first turbine components are planned to come though Newtown in mid-January. I firmly believe that the Welsh Government should not be allowing them to use this route, as the new Newtown Bypass will be opened just a few weeks later.
"As it stands, the components will be transported via abnormal heavy goods vehicles along the A483, under Nantoer Bridge, a bridge under which numerous HGVs and large vehicles have got lodged previously. With the Newtown Bypass due to open imminently, you have to wonder why the transportation of these turbines isn't just put back by a few weeks.
"I have written to the Welsh Government requesting urgent clarification about the developer's traffic management plans in order to gain assurances that the people of Newtown will not be subjected to disruption; the transportation of this equipment will not delay the construction of the Newtown Bypass; and whether or not the Welsh Government believes that the transportation of this heavy equipment has been planned correctly.
"The developers and Welsh Government Ministers should not only be concerned about the wind turbine components getting to their destination ahead of time, but should also be aware of any significant congestion that may be caused behind these abnormal delivery vehicles and the wider effects which this will have on the Mid Wales economy."
