State Highway 43 has been closed since 15 October after a slip came down at Tunnel Hill, 23km west of Taumarunui, in September and subsequent land movement caused the road to move further.
A popular touring route, the Forgotten Highway links National Park to Taranaki via Taumarunui and Whangamomona before emerging at Stratford.
Sheep and beef farmer Murray Craig walked across the slip site, which has cut his farm in two, to talk to RNZ.
His shepherd Alex Gower saw the landslide.
"As it happened he was going home and he saw a crack on the side of the road and stopped and while he was watching a second crack appeared," said Mr Craig.
"He stayed there for about two hours. He rang Downers. And the whole road slipped out before his eyes."
Mr Craig said ultimately everyone was being hit in the pocket.
"I'm sure if I was to get fertiliser carted now it would cost $3 or $4 a tonne extra to go the long way.
"The meat companies cover the cost. They pay for the freight but you know what it does, it takes it off what we ultimately get or adds onto what you pay for it."
The one-hour detour starts north of Taumaraunui and has left Lauren's Lavender Farm and Cafe high and dry.
Owner Lorraine Gawith says visitor numbers have plummeted.
"The road here for me is tourism with foreigners. That's what keeps this little business ticking over so with the slip there's not a lot of people coming on the road.
"On that road we can get up 80 people through the day quite easily and it's dropped down. We maybe get 20 at the most, if that."
Ms Gawith said that was not sustainable long term.
"I'm hoping they get the road open because we really can't continue on the way it is. So, yes, I want that road to be fixed soon."
Omaka Lodge co-owner Scott McPherson said its bookings were mostly from overseas and holding up, but his guests were miffed they could not tour the Forgotten Highway as planned.
"Really, they can't believe in this day and age that a major tourist route could actually be closed as long as this and that until now there's been a lack of information from the relative authorities about what is happening to repair it and actually get it going."
Mr McPherson said communication from the Transport Agency had not been the best.
"We've been told it will possibly open to one-lane traffic in the next two to three weeks. That's not trucks just cars.
"But again, there's been no concrete date given to us so we just wish we could get a bit more clarity from NZTA about actually what the plan is for a) to clear the slip and b) to being proactive for future works."
Forgotten World Adventures co-owner Ian Balme said it was using the detour and it was business as usual.
He said disruption caused by the slip reinforced how important the Forgotten Highway was becoming.
"Look, State Highway 43 is a really important tourism route and there's the beginning of a realisation of just how important it is.
"And clearly if we can manage to get that last twelve kilometres sealed it will become a critical tourism route. It's already internationally recognised and it will only get better."
Meanwhile back at the slip, it appeared the message the road was closed was still not getting through to everyone.
Argentinean visitors Joanne and Ignacio blamed technology.
"We thought that the road closed signs were just because there were bridges. It wasn't super clear and plus Google Maps didn't tell us we couldn't come."
Transport Agency system manager Mark Owen trees had been felled and a digger was now operating at the Tunnel Hill slip site.
Mr Owen said it was hoped to have one lane open before Christmas.
"Our ability to this is dependent on the weather remaining fine and the stability of the hill face. Land is this area is highly unstable, so we need to work carefully to avoid causing further slips and to ensure the safety of the work team."
Mr Owen said options for a permanent repair were still being considered.