Labour councillor Paulette Smith is leading the calls for the authorities to act urgently following another crash on the A4067 near Glais.
The plea for traffic calming measures, which is part of a cross party approach including Plaid Cymru councillors in Neath Port Talbot, comes after an 11-year-old boy was airlifted from the scene of a crash between six cars and an empty coach on June 4.
“This has become an unacceptable situation which needs very urgent action,” insisted Cllr Smith, the Labour member for the Clydach ward.
“There are incidents happening on that bypass on a weekly basis and there have been tragic fatalities in the past. This was a June morning not a dark day in November.
“It is high time that the Welsh Assembly and the local authorities did something urgently to eradicate the problems at this accident black spot.
“I have been touch with fellow councillors in the area and we are all of the same opinion that something needs to be done very quickly to avoid similar incidents.
“Motorists hit the Glais roundabout at excessive speeds and we need traffic calming measures such as rumble strips to slow people down.”
Cllr Smith’s stance has been backed up by a group of Plaid Cymru councillors – Linet Purcell and Anthony Richards (Pontardawe), Rebeca Phillips (Trebanos), Alun Llewelyn (Ystalyfera) and Ros Davies (Godre’r Graig)
They said in a statement: “As Plaid Cymru councillors representing wards in the Upper Swansea Valley we would be supportive of any attempts being made by Cllr Paulette Smith, in whose ward the accident black spot is located, to improve the safety of this very dangerous road,”
South Wales Police arrested a 75-year-old man in connection with the smash the smash on the A4067.
The road, between Glais and Pontardawe, was closed for investigations but later reopened.