Hundreds of eisteddfod-goers were held up in traffic delays after an accident during the rush hour caused three mile tailbacks on the M4.
Traffic was slow moving following an accident
The accident, between a lorry and a car, happened just before 0900 BST on Monday near junction 28.
No-one was injured in the collision, but traffic built up causing delays.
Police said that motorists travelling to Newport from the west added to the delays by not following the signed route to the festival.
Some visitors to the National Eisteddfod complained of taking more than an hour to travel three miles because of the delays.
But police and organisers for the festival said that they would be taking steps to ease the build up of traffic for the remainder of the festival including opening more car parks.
Organisers asked people to be patient when travelling to the event and police said that they would be looking at ways in which to encourage motorists to follow the planned routes to prevent bottlenecking at junction 28.
Visitors faced long delays on the M4
Pc Dorian Evans from Gwent Police said: "We have had problems this morning.
"We expected it to be busy between 10 and 12 but unfortunately there was an accident on the M4.
"That was in addition to people travelling to work and it seems that people travelling from the west were going right up to junction 28 instead of using the A48 as signed."
He said that they would be looking at ways of getting people to use the correct routes in order to prevent similar problems for the rest of the event.
Meanwhile, organisers said they have been pleased with the response from the public to the event.
More than 31,000 people attended over the weekend.
Elfed Roberts, director of the eisteddfod said that many of the visitors were local to the area.
"Many of the people who came have been local people and we have been very happy with this," he said.
"We have been talking to people around the maes and they seem to be very happy with the arrangements we have put in place.
"It is very heartening," he added.