Waipu Chief Fire Officer, also a local tow truck driver, Trevor Vaile said he "knows for a fact" trucks had difficulty negotiating the narrow lanes between the road cones and the barrier during that work.
Rather than applaud the expensive road improvements as a likely life saver, Mr Vaile has concerns about associated new road hazards.
He said there had already been a significant reduction in serious injury crashes on that stretch of SH1 after the speed limit was reduced to 80km/h and roading police patrols increased.
"All this work that has been done was unnecessary. I have extreme concerns about the new road, where the viewing spot is located, the danger of traffic crossing the centre into it, and the impact of the barrier on residents living on the western side of the hill."
There were several safer places - with better views - where the site could have been created, Mr Vaile said.
During the planning stage of the project, Waipu Fire Brigade made a submission to New Zealand Transport Agency (NZTA) opposing the barrier.
Tangihua resident Wayne Deeming has also slated the site of the viewing stop.
"It defies belief that a right turn across two lanes of a divided highway is representative of a 'safe system' approach, as NZTA says it is," Mr Deeming said.
He said providing a "camera stop" was not a good enough reason to have a break in a wire rope barrier in a perceived high crash area.
A similar viewing stop could have been created on the other side as well, he said.
But Mr Bain said he did not share the concerns about traffic crossing lanes to get to the viewing site.
''I don't think it is as deadly as people are making out because there is good visibility on both sides of the road.''
However, as the matter had been raised, Mr Bain said he would ''sound it out'' at the next transport committee planning meeting.
Despite the better road, police are urging people to drive the Brynderwyn stretch sensibly and cautiously, especially as the wetter winter months loom.
Road policing Senior Sergeant Ian Row said improvements and wire barriers themselves do not reduce the biggest factor behind serious crashes, which is speeding and other unsafe driving behaviour.
"The major benefit will be in reducing the severity of those crashes."
Regarding the viewing site concerns, Mr Row said people should always drive to the conditions.
''Let's clarify, no one has to do anything. If it looks too busy or dangerous, then don't stop there.''