Thousands of more vehicles will be diverted through Newtown after the Welsh Assembly Government confirmed the main road from Welshpool to Dolgellau will be closed from 8.30am-5.30pm for at least 11 days from January 10.
Emergency works are being carried out on the trunk road at Cwm Dugoed which means coast-bound motorists will reach Dolgellau by driving through Newtown to Caersws before joining the A470 north-west to Mallwyd.
It will divert more vehicles through the already congested Newtown centre which is close to bursting following the bridge damage at Aberbechan that cut off a popular side road into the town.
Campaigners face a worrying few months with the Welsh Assembly expected to make its decision soon on whether to include a bypass for Newtown in its spring budget.