Two people travelling in the campervan were also injured and taken to Thames Hospital.
Mrs Grace said while that crash had been a tragedy, roading improvements in Waikato had contributed to other potentially fatal crashes being avoided.
"While expressing our sympathies to the families affected we are also reflecting on a very close call on Sunday that saw a potential loss of live averted due to road engineering improvements.
"That incident involved an elderly woman travelling south on SH1 near Te Kauwhata about 1pm who became distracted and drifted into the centreline towards oncoming traffic."
Fortunately for the woman, and oncoming motorists, wire rope barriers have been installed along much of SH1 meaning the woman escaped injury or even worse, though her car was badly damaged, Mrs Grace said.
"Engineering, education and enforcement form the pyramid of road safety and in this case engineering enhancements saved at least one life."
A Waikato campaign asking people to dob in bad driving behaviour, Make it to Monday, saw 285 reports made during the long weekend, she said.
"Many calls involved people overtaking in inappropriate areas or crossing the centreline so these calls play an important part for us in terms of preventing road trauma.
Mrs Grace said during the weekend seven drivers were found to be driving while over the legal alcohol limit, with two in Te Kauwhata and five in Hamilton. "That's seven interventions by police that prevented potential fatalities," she said.
