Earlier Ms Genter told Mr Heath that 49.3 per cent of SH1 between Kaitaia and Warkworth would come into the category of 'dangerous,' and would therefore be subject to a lower speed limit, although that would not be inevitable. While speed reductions were possible, depending on the function of the road, engineering improvements that would make current speed limits safe would also be considered by the NZTA.
Almost 8 per cent of 6652km of other roads in Northland would fall into the'dangerous' category.
In response to a question regarding what work, if any, had been done to gauge the economic impact of reducing speeds on "dangerous" roads, Ms Genter said the NZTA had considered various reports and research, traversing safety benefits, travel time costs, vehicle operating costs, air pollution costs for cars, light commercial vehicles and heavy commercial vehicles travelling at different speeds, people's willingness to comply with lower speed limits, mean operating speeds across the road network, and those parts of the road network that would generate the greatest benefits in terms of reducing death and injury rates when speeds were reduced to a "safe and appropriate" level.
Mr Heath said the NZTA had already advised him, in response to an OIA request, that it did not have information about vehicle speeds at the time of crashes, however.
"How then does it justify its claim that reducing the speed limit to 80km on half of SH1 traversing Northland will reduce the number of crashes?" he asked.
"As I understand it, with SH1 in its current state — i.e. without any additional engineering undertaken by NZTA — half of Northland's main economic artery and principal road connection to the rest of the country would be subject to a lower maximum speed limit under the review already being conducted by the NZTA, along with an additional 513km of other roads in Northland."
He also wanted to know what proportion of the 165.8km of SH1 between Kaitaia and Warkworth that had been assessed by the NZTA as in the top 10 per cent of dangerous roads was 'fixable' via engineering work, and what proportion was likely to simply have a maximum limit of 80km/h "slapped on it."