There are fears the 19-mile landslide could last for months.
BBCLandslides caused by Storm Darragh mean that what was a six-mile journey is now 25 miles.
The A487 has been closed between Corris and Minford, Gwynedd since Wednesday due to concerns about unstable ground above the road.
The Welsh Government said it hoped the case would be resolved soon but feared the case could remain closed for several months.
Builder Martin Jones, who was driving towards Dolgellau shortly after the landslide caused by Storm Darragh on Saturday, said: “If I had been there 10 minutes earlier, I could have been caught in the landslide and, you know, I would have been trapped. Would have been trapped or perhaps worse.”
Mr Jones, from Aberlefenni, said the closure was an inconvenience as his young daughter goes to a nursery in Brithdir and the journey “which usually takes a quarter of an hour” now takes 45 minutes each way.
martin jonesDennis Jones, of Corris, was stunned by the scale of the landslide.
He said: “The amount of ground, mud and trees that have fallen is incredible. Fortunately, they were cleared very quickly by a local contractor.”
“But since then, they’ve surveyed the actual land left on the slope, and apparently that’s very, very dangerous and still unstable.”
He said there is little information about when the road will reopen, “Some have said a few days, others have said 10 to 15 days. But this morning someone said it could take up to two or three months.” Could.”
The Welsh Government said the road has been closed for safety reasons and the North and Mid Wales Trunk Road Agent is trying to fix the road “as quickly as possible”.
