"And this was happening at the busiest time of the school day with parents dropping off kids at the school. If something wasn't done then the same thing would have been repeated in the afternoon," he said
He said state highway work is a NZTA responsibility but as it was not an emergency event, such as a traffic accident or road washout, users should have been notified.
"If council is doing this sort of work and roads will be closed temporarily then there are letterbox drops and other ways of warning locals what's going to be happening," he said.
David McGonigal, NZTA regional highways manager, told the Chronicle the closure happened because a faulty culvert had to be repaired.
"If faulty culverts are not repaired in a timely manner, it can undermine the road and cause it to collapse, hence the urgent nature of this work."
Mr McGonigal said closing SH3 was not planned because at first it was thought the work could be carried out without disrupting traffic movements.
"However, ground conditions proved to be worse than anticipated, meaning that to fix the culvert, we had to dig up the full width of the road. This resulted in the highway being closed at short notice."
He said NZTA strived to keep state highways open 24/7 but yesterday's closure was "an extremely rare event that resulted from exceptional and unforeseen circumstances".
"Under normal circumstances, we would inform locals, council and other affected parties well in advance of the work being carried out.
"We apologise to the public for this unexpected inconvenience, and we will be having a good think about what we might be able to learn for next time," Mr McGonigal said.
He said NZTA appreciated the closure was disruptive for the local community, and it was working to get the job done as quickly as possible.
It hoped to have SH3 reopened to one lane late yesterday.