Breakthrough Findings from the KiwiRAP Study
A groundbreaking report titled 'Have New Zealand’s Highest Risk Highways Improved?', released by the AA Research Foundation in collaboration with WSP, has delivered compelling evidence that targeted infrastructure investments are paying off on the country's most dangerous state highways. Launched as part of the KiwiRAP (New Zealand Road Assessment Programme) initiative, the study revisits 35 high-risk corridors identified back in 2008, revealing a remarkable 20.4% reduction in fatal and serious crashes compared to just 4.6% on the broader rural road network. This progress is even more impressive given that traffic volumes on these routes have surged by approximately 50% over the assessed period. The analysis equates to around 20 fewer fatal crashes annually across these highways, underscoring the life-saving impact of strategic upgrades.
KiwiRAP, established in 2008 through a partnership between the NZ Automobile Association, Ministry of Transport, NZ Transport Agency (NZTA or Waka Kotahi), ACC, and NZ Police, uses star ratings—similar to EuroRAP—to pinpoint sections where road design poses the greatest threat to users. Collective risk (crashes per kilometre) and personal risk (crashes per vehicle kilometre travelled) guide priorities, ensuring investments target areas with the highest potential for harm reduction under the Safe System philosophy. This approach accepts that human error is inevitable but designs roads to forgive mistakes, protecting users from severe outcomes.
Methodology: A Rigorous Longitudinal Assessment
The study's methodology provides a robust foundation for its conclusions. Researchers compared crash data from two five-year baseline periods: 2002–2006 (pre-KiwiRAP assessments) and 2017–2023 (excluding COVID-impacted 2020–2021 to avoid distortions). Data came from NZTA's Crash Analysis System (CAS), with vehicle kilometres travelled (VKT) back-calculated for consistency. Video footage from Argus Roadrunner surveys in 2008/09 and 2023/24 allowed visual confirmation of infrastructure changes.
Originally 32 corridors, the analysis expanded to 35 links by splitting complex sections (e.g., SH29/SH2 in Tauranga). Improvements were categorized as minor (e.g., signage), block (moderate), or major capital (e.g., bypasses lasting over 12 months). Risk metrics focused on fatal and serious injury crashes, aligning with Road to Zero—the government's 2020–2030 strategy aiming for a 40% reduction in deaths and serious injuries by 2030. This evidence-based method not only quantifies progress but highlights where further action is needed.
Overall Results: 20% Crash Drop Amid Rising Traffic
Across the 35 links, 827 fatal and serious crashes in the early period dropped to 658 in the later one—a 20.4% decline. This outpaces the national rural average, demonstrating KiwiRAP's role in directing NZTA investments effectively. Personal risk remained stable or decreased on most routes, though four saw upticks due to recent upgrades potentially encouraging higher speeds—a phenomenon to monitor.
Of the 26 links with significant interventions, reductions averaged 28.4%, while nine with minor work saw only 4.3%. Nine corridors achieved over 50% drops, saving countless lives. The full KiwiRAP 2025 report details these metrics, including appendix maps of upgrades.
Standout Success Stories: Highways Transformed
Several routes exemplify the power of bold infrastructure. State Highway 20B to Auckland Airport saw an 86% plunge in fatal/serious crashes after new road construction and transit lanes. SH2 from Bethlehem to Mount Maunganui dropped 78% thanks to a partial bypass around Tauranga city centre. SH1 from SH74 to SH73 in Christchurch achieved 64% reduction via major upgrades.
- SH20B Auckland Airport: 85.7% reduction – new alignment and lanes.
- SH2 Bethlehem-Mount Maunganui: 77.8% – partial bypass.
- SH1 Christchurch section: 63.6% – extensive safety enhancements.
- Napier-Hastings: 60% – significant works.
- Mount Maunganui-Paengaroa: 50% – bypass/partial bypass.
These cases highlight how bypassing high-risk urban sections and adding barriers mitigate head-on and run-off crashes, common killers on undivided highways.
Infrastructure That Delivers: Barriers, Bypasses, and More
The study attributes success to 'transformational' changes: full/partial bypasses, continuous median/roadside barriers, motorway extensions, and realignments. For instance, Mangatawhiri partial bypass on SH2 Pokeno-Mangatarata cut crashes 51.4%. Barriers prevent cross-median incursions, while bypasses eliminate congestion hotspots.
NZTA's implementation under Road to Zero has accelerated these, with median barriers now standard on high-risk open roads. Wide centrelines and rumble strips complement, but major projects yield outsized returns. Mark Newsome, WSP Technical Principal, notes: “Transformational improvements deliver transformational results... the returns in human and economic terms are substantial.”
| Improvement Type | Average Crash Reduction | Examples |
|---|---|---|
| Bypasses/Partial Bypasses | 50-86% | SH20B, SH2 Tauranga |
| Median/Roadside Barriers | 28.4% (group avg) | SH1 Christchurch |
| Motorway Extensions | High | SH20 Wiri-Mt Roskill |
| Minor/Signage | 4.3% | Various |
Challenges: Where Risks Persist or Worsen
Not all news is positive. Six corridors saw rises: SH1 Cambridge-Piarere (+75%), SH2 Katikati-Tauranga (+44%), SH1 Marsden Point-Whangarei (+23%), SH1 Auckland-Takanini (+13%). These lacked major upgrades, with traffic growth amplifying risks. Recent Cambridge bypass effects aren't yet in data (opened 2024).
Personal risk increased on four post-upgrade links (e.g., Orewa-Warkworth), possibly from speed creep. Dylan Thomsen, AA Safety Manager, urges: “We need to keep investing... in replacement highways or significant upgrades.” This highlights the need for ongoing monitoring and swift action.
Traffic Boom Meets Safety Gains
New Zealand's roads handled 50 billion VKT by Sept 2025, up significantly. Yet 2025 road toll hit 272 deaths—lowest since 1920s, down from 292 (2024), per NZTA. Road to Zero contributes, with infrastructure pivotal. Without KiwiRAP targeting, gains would lag.
Safe System—safer roads, speeds, vehicles, users—drives this. NZTA's $1.4b plan targets worst roads, aligning with GPS 2024-34.
Stakeholder Views: Praise for Evidence-Based Action
Experts applaud. AA's Dylan Thomsen: “Safety has improved dramatically... but invest where risks are highest now.” WSP's Mark Newsome: “Invest in the right infrastructure... hundreds of lives saved.” NZTA credits KiwiRAP for prioritizing. iRAP notes 20 fewer fatals/year.
Road to Zero oversight reports steady progress toward 40% DSI cut by 2030, with infrastructure key pillar.
Future Outlook: Sustaining Momentum
Recommendations: Sustain KiwiRAP, prioritize remaining high-risk links with major works, monitor post-upgrade speeds. NZTA's Speed & Infrastructure Programme targets open-road barriers, safer speeds. With 2025's record-low toll, continued $billion investments could achieve Zero vision.
Challenges: Funding, urban growth, climate risks. Opportunities: Tech like flexible barriers, data-driven audits.
Implications for Policy and Practice
This validates Safe System ROI: $4-12 saved per $1 invested in barriers/bypasses. Policymakers should accelerate RoNS (Roads of National Significance). Local councils aid rural high-risk roads via guides.
iRAP's analysis reinforces global best practice.
Photo by Nik Schmidt on Unsplash
Actionable Insights for Safer Roads Ahead
- Prioritize bypasses/barriers on high-risk SH.
- Use KiwiRAP star ratings for investment.
- Monitor speeds post-upgrade.
- Integrate with Road to Zero: safer speeds/vehicles.
- Engage communities for buy-in.
New Zealand's progress inspires; sustained effort can eliminate road trauma.