People living near a new wind farm say they fear the main road serving it will not be able to cope with large lorries needed during construction.
A public meeting is taking place in Cwmgors on the A474 near Ammanford on Monday to highlight concerns.
Construction of 15 turbines with a tip height of 110 metres (360ft) is due to start in the next few weeks.
Neath Port Talbot council said the road could cope, and the wind farm operator said safety was its top priority.
The Mynydd y Betws wind farm lies on the border between Carmarthenshire and Neath Port Talbot.
Carmarthenshire council dealt with the planning application for the wind farm and Neath Port Talbot with site access.
Lorries needed for earthworks and to deliver the turbines will access it via the A474 travelling from Pontardawe.
But residents in Cwmgors are urging the council to look again at the access plans.
‘No hope of passing’
Pastor Ron Williams said: “It’s of great concern because the road is very difficult under normal circumstances.
“The vehicles that are going to be coming here are 55 yards (50 metres) long.
“Vehicles, including the emergency services, have no hope of passing.
“It seems as tough that [the council] is not prepared to listen to our concerns or at least treat them seriously.”
Geoff Moore, one of the organisers of the public meeting at Cwmgors Rugby Club, said the aim was to raise awareness as work was due to start soon.
“This road is dangerous and it’s already got ample traffic on it,” he added.
According to the operator Cambrian Renewable Energy. the wind farm will generate enough electricity to power about 23,800 homes.
It said it would work with the council and police who will escort abnormal deliveries to ensure minimum disruption.
The construction process was expected to result in a temporary increase in traffic on the A474 of 2.5% on average from the existing levels.
“Safety is our top priority, and Cambrian Renewable Energy is committed to ensuring that the construction process occurs with minimum inconvenience to the local community,” a spokesperson said.
“Suitable traffic management measures will be put in place to achieve this.’
Neath Port Talbot Council said it raised concerns over the visual impact of the turbines but the plans were approved.
A spokesperson said: “In relation to the proposed access, the council have, in the determination of the planning application, considered the traffic issues in relation to the use of the access during both the constructional and operational phases.
“[Councillors] concluded that the traffic movements associated with the development would not have a detrimental effect on highway safety.”