Fears that traffic jams could disrupt the National Eisteddfod have led to calls for the Welsh assembly government to limit the problems.
Last year's eisteddfod was held in Newport
Organisers have voiced concerns ahead of the week-long event, which starts on 30 July at the Faenol Estate near Bangor.
Work to repaint the nearby Menai Bridge has added to congestion in the area.
The assembly confirmed work would continue but that talks about traffic problems were ongoing.
The work at Menai Bridge, which is one of only two bridges onto Anglesey, involves lane closures which mean that vehicles only can only travel in one direction at any time.
Richard Morris Jones, chair of eisteddfod's executive committee, said he was "extremely worried" that congestion "could have a detrimental effect on the eisteddfod in some form or other".
"Traffic on the Faenol roundabout and the bridges is extremely bad at times, especially during holiday times and, as we know, the middle of August is holiday time," he said.
"I do stress I appreciate the difficulties - we need a support package in place to make absolutely sure there is a firm and very precise traffic flow management for the whole of the week."
The assembly has said that they are actively looking at ways of alleviating possible traffic problems during the eisteddfod, including special trains and additional park and ride facilities.
The Menai Bridge has not been painted for 65 years
An assembly spokesman warned that stopping the painting for one week would cost a total of up to £750,000, as it would mean six weeks dismantling the scaffolding on the bridge, and six weeks reassembling it.
He added that it would mean work would also be delayed for six months, as contractors would have to stop in October and restart in the spring.
William Day, the engineer in charge of repainting the Menai Bridge, agreed that stopping the painting would not be easy.
"By stopping, they actually mean clear the bridge of all works going on at the moment - to put that in context, we have actually got 300 tonnes of scaffolding on this bridge," he said.
Discussions between the assembly, Gwynedd council, the police and Eisteddfod organisers are ongoing. Heather Lynne Jones, from Gwynedd council, said eisteddfod visitors should keep to specific routes and follow AA signs.
"There's no reason why traffic shouldn't flow easily during the week if drivers stick to the guidelines provided,' she said.