He said when the roundabout became operational he told his wife that a truck would roll because of the camber.
"Lo and behold only a few days afterwards that is exactly what happened.
"Since that time I have spoken to many drivers and operators within the industry and all agree that the camber is wrong."
He was aware that following the first incident the road alignment and camber was checked and deemed to be within standard and recognised design tolerances.
"That may well be the case and the camber at any one point in the route through the roundabout may well meet the criteria.
"The problem here almost certainly lies in the sudden change of camber part way through the roundabout."
He urged the Transport Agency to take the issue "seriously before someone is seriously hurt".
"Just imagine that a heavy vehicle was to transit the roundabout in the outside lane, and don't think for one minute that this doesn't happen, and that a family car with passengers and children was coming through on the inside.
"It's not too far fetched and it is preventable."
In the latest crash, a truck carrying 15 tonnes of MacDonalds fries crashed at the roundabout at about 1.30pm on Thursday.
Sergeant Mike George of Kapiti police said the northbound truck had gone around an outside lane and "for some reason, rolled over".
"We're getting video footage from the Transport Agency and the truck cam, and the GPS on the truck will give us some idea of the speed. It's too early to say what the cause is.
"From what we can gather, he's followed a petrol tanker around the corner, and didn't seem to be doing anything different to that vehicle."
The 35-year-old male driver, from Feilding, had a seatbelt on.
"If he didn't have a seatbelt on he would have been severely injured."