Crash figures link drop in speeds to lives saved

Figures released under the Official Information Act suggest a lowered speed limit on an infamous stretch of State Highway 2 has brought early safety gains. Photo / Sarah Ivey

Crash data from a notorious piece of road popular with Auckland holidaymakers could hold clues on how to lower New Zealand's road toll.

Figures released under the Official Information Act suggest a lowered speed limit on an infamous stretch of State Highway 2 has brought early safety gains - reducing deaths and serious injuries by 27 per cent and cutting the crash rate by 26 per cent.

The data is from a 30km section of SH2, which links SH1 near Pokeno and SH25 near Maramarua, and is used by people travelling between Auckland and the Coromandel Peninsula - a hotspot route for family holidays.

When it comes to safety, that road corridor has previously been highlighted as one of the worst-performing sections of state highway in the Waikato and is subject to very high traffic volumes. New Zealand Transport Agency numbers say volume varies from 14,500 vehicles a day to up to 24,000 in peak holiday periods.

Work to tackle safety in the area, where 26 people were killed between 2002 and 2011, began with the NZTA looking at how to manage speed and on December 16, 2011, parts of the 100km/h speed limit were cut to 90km/h. An urban section of the road at Maramarua remained at 70km/h.

NZTA numbers show the crash total stayed at 13 in 2012 and deaths rose from two to three. But total crash numbers more than halved to five in 2013 and six in 2014. For the first time since 2006, no one died on the road in 2013 and only one died last year.

The NZTA says although speed is only one factor in accidents where other major issues such as drink-driving also exist, the SH2 numbers are proof of increased safety.

"As a result of the speed limit being [cut] from 100km/h to 90km/h there has been, on average, an 8-10km/h reduction in mean vehicle speeds and a 27 per cent reduction in road deaths and serious injuries," said NZTA highway manager Kaye Clark.

But not all are convinced the data is conclusive. Road safety campaigner Clive Matthew-Wilson, who edits car review website dogandlemon.com, says although it's reasonable to lower the speed limit in high-risk areas, the SH2 statistics are not reliable.

"These are not reliable figures, because there are always jumps and falls from one year to the next," he said.

"For example, in the year after the lowered speed zones were put in place, the number of fatalities actually increased substantially, from two to three. Similarly, there was one serious accident on this stretch in 2012 and three in 2013.

"It would be ridiculous to claim that the lowered speed limit had tripled the number of serious accidents. Any statistician will tell you, you can't use single-digit figures over a relatively short timeframe to try and prove or disprove the effectiveness of a campaign."

In response, the NZTA said the numbers should also be considered in the light of a spike in car numbers on Kiwi roads over the past year.

"The challenge which lies ahead is to continue that downward trend ... made even harder in light of a sharp increase in traffic volumes over the past 12 months," a spokeswoman said. "One of the most tragic aspects of serious road crashes is that nearly all of them are preventable."

The NZTA would keep working with police, the Automobile Association and others to create a safe system for all, she said.

There had been dozens of cases where speed limits on the state highway network had been reduced, either permanently or temporarily, and it reviewed limits across about 11,000km of highway nationwide.