KiwiRAP Star Ratings Q&As
1.What is KiwiRAP?
KiwiRAP is part of an international family of Road Assessment Programmes (RAP), under the umbrella of the international Road Assessment Programme (iRAP). The RAP programme is a sister programme to the international New Car Assessment Programme (NCAP), known as ANCAP in New Zealand (the Australasian New Car Assessment Programme).
KiwiRAP is a partnership of the Ministry of Transport, NZ Automobile Association (NZAA), ACC, NZ Police, and NZ Transport Agency (NZTA) that was formed in 2006.
The first protocol, the Risk Maps which rated sections of state highways from low to high risk based upon crash history, were released in January 2008.
The second protocol (performance monitoring) periodically updates the risk maps.
The third protocol (which this document covers), is Star Ratings, which are derived by rating the level of risk associated with the physical attributes of rural state highways and how these influence the crash likelihood and severity for head-on, run-off road and intersection type crashes. KiwiRAP uses Star Ratings to classify rural state highways from 1star (least safe) to 5 stars (safest) based on a road’s inherent safety features.
2.Why has KiwiRAP been established?
By giving roads across New Zealand a safety rating, KiwiRAP will make the risk of death and injury on different roads more meaningful and stimulate public discussion — and action.
All roads are not equal. Motorists need to be aware that some roads are safer than others, so they can drive to the conditions and take care on higher risk roads. The Star Ratings will help road users understand how risk can vary according to changes in the road environment. Risk-aware road users will be more likely to adapt their driving to reduce their risk of a crash.
The star ratings will also provide the NZTA (who operate the State highway network) with vital benchmarking information to show them how particular roads perform compared with others. This will be used to help with their decisions on road improvements based on risk and needs.
3.Which roads have been given Star Ratings?
KiwiRAP has focused on star-rating rural sections of the State Highway Network. These are sections with speed limits of 80 km/h and over, which is generally in line with RAP models in similar developed countries such as Australia and western Europe.
KiwiRAP has assessed the safety performance of 10,187kms or 91% of New Zealand state highways. These are the sections with speed limits of 80km and above. KiwiRAP has provided star ratings for 10,002kms or 89% of these New Zealand state highways.
- How will people know if they’re driving on a 2, 3 or 4-star road?
All the KiwiRAP Star Rating maps and information can be viewed and downloaded at The KiwiRAP data analyses what sort of roadside conditions affect the Star Rating of a road. At this stage, we want to raise public awareness of the roadside environment so drivers understand and recognise what hazards can be eg, unprotected trees, embankments etc. They can then change their driving behaviour accordingly, as they do when they drive to the conditions.
Most drivers are able to recognise that when driving in treacherous terrain (they can recognise cliffs and water features) they would be on a low starred road and when they are driving on motorways/expressways they would be driving on a high starred road. However, many drivers would treat all other rural roads as the same (they cannot recognise roadside hazards like trees, ditches poles, narrow shoulders and culverts). Over time it would be good for drivers to recognise the difference between a 2 star road with severe roadside hazards, 3 star and 4 star roads, and change their driving behaviour accordingly.
The images in Appendix 1 give examples of what types of hazards drivers could possibly see on each level of starred road.
- How are Star Ratings determined?
The Star Ratings are derived by rating the level of risk associated with the physical attributes of the road and roadsides and how these influence the crash rates and severity for head-on, run-off road and intersection type crashes.
Specially equipped vehicles record digital video images of a road using an array of cameras, which log safety features when travelling along the road at almost highway speeds.
Highly-trained analysts then conduct a virtual drive-through of the road network using specially developed software to make accurate measurements of road elements. These elements include lane widths, shoulder widths and distance between road edge and fixed hazards, such as trees or poles. The relative risks in the road design features are combined in mathematical formulas to create a Road Protection Score (RPS) for every 100m of highway which are then averaged over 5km lengths to generate a Star Rating from one to five.
- What sorts of things affect a road’s safety rating?
There are many road design features that impact on the likelihood of a crash occurring and its severity – and therefore the road’s Star Rating. The main ones include:
- whether opposing traffic lanes are separated by a physical barrier or wide median (whether the road is divided or undivided)
- the safety of the roadside, including the presence of unprotected trees, poles and steep embankments
- lane width
- sealed shoulder width
- alignment (number and sharpness of curves)
- terrain (flat, rolling or mountainous)
- quality of line marking & signage
- overtaking provision
- intersection frequency & layouts.
- How well do New Zealand’s rural state highways fair in the KiwiRAP Star Rating report?
The results reveal five percent of rural state highways rated 4 stars, 56 percent 3 stars and 39 per cent were 2 stars. We have no 1 star or 5-star roads.
It is important to note that while only 5 percent of our roads are 4 star, 28 percent of New Zealand’s traffic occurs on our 4-star roads, 40 percent on our 3-star roads, and 33 percent on our 2-star roads.
Distribution of Star Ratings
% / Kms / * / ** / *** / **** / *****Northland / 656 / - / 36 / 64 / - / -
Auckland / 399 / - / 28 / 8 / 64 / -
Waikato / 1560 / - / 39 / 58 / 3 / -
BOP / 663 / - / 42 / 56 / 2 / -
Gisborne / 311 / - / 54 / 46 / - / -
Hawkes Bay / 452 / - / 43 / 57 / - / -
Taranaki / 749 / - / 59 / 40 / 1 / -
Mana-Wang / 445 / - / 49 / 51 / - / -
Wellington / 239 / - / 26 / 38 / 36 / -
Nelson/Tas / 353 / - / 43 / 54 / 3 / -
Marlborough / 241 / - / 47 / 53 / - / -
Canterbury / 1186 / - / 26 / 71 / 3 / -
West Coast / 818 / - / 50 / 51 / - / -
Otago / 1217 / - / 30 / 69 / 1 / -
Southland / 713 / - / 37 / 63 / - / -
NZ / 10,002 / 0% / 39% / 56% / 5% / 0%
Proportion of vehicle kilometres travelled for each Star Rating by region
% / VKTX108 / * / ** / *** / **** / *****
Northland / 7.73 / - / 35 / 65 / - / -
Auckland / 35.59 / - / 9 / 3 / 88 / -
Waikato / 25.19 / - / 38 / 55 / 7 / -
BOP / 10.91 / - / 51 / 45 / 5 / -
Gisborne / 1.42 / - / 57 / 43 / - / -
Hawkes Bay / 5.62 / - / 33 / 67 / - / -
Taranaki / 6.75 / - / 62 / 37 / 1 / -
Mana-Wang / 8.77 / - / 50 / 50 / - / -
Wellington / 13.24 / - / 16 / 31 / 53 / -
Nelson/Tas / 3.49 / - / 58 / 28 / 14 / -
Marlborough / 2.56 / - / 63 / 37 / - / -
Canterbury / 15.61 / - / 34 / 61 / 6 / -
West Coast / 3.48 / - / 54 / 46 / - / -
Otago / 9.92 / - / 38 / 56 / 6 / -
Southland / 4.48 / - / 44 / 56 / - / -
NZ / 154.76 / 0% / 33% / 40% / 28% / 0%
Key safety features
% / Length / Divided / GoodHorizontal
Alignment / Safe
Roadside / Wide Lanes / Good
Sealed
Shoulder
Width / Good /
Excellent
Delineation / Intersections
Northland / 683 / 0 / 63 / 16 / 90 / 10 / 95 / 1 every 2km
Auckland / 429 / 65 / 81 / 52 / 98 / 43 / 99 / 1 every 1km
Waikato / 1585 / 3 / 57 / 16 / 81 / 14 / 84 / 1 every 2km
BOP / 680 / 3 / 66 / 19 / 97 / 20 / 98 / 1 every 2km
Gisborne / 313 / 0 / 55 / 16 / 100 / 1 / 100 / 1 every 2km
Hawkes Bay / 475 / 2 / 69 / 21 / 100 / 7 / 95 / 1 every 2km
Taranaki / 766 / 0 / 67 / 14 / 99 / 8 / 79 / 1 every 2km
Mana-Wang / 450 / 0 / 82 / 25 / 100 / 24 / 97 / 1 every 1km
Wellington / 246 / 44 / 79 / 43 / 100 / 42 / 100 / 1 every 1km
Nelson/Tas / 356 / 2 / 62 / 19 / 100 / 12 / 97 / 1 every 2km
Marlborough / 241 / 0 / 76 / 20 / 100 / 14 / 99 / 1 every 2km
Canterbury / 1202 / 2 / 81 / 32 / 100 / 13 / 99 / 1 every 2km
West Coast / 826 / 0 / 66 / 8 / 100 / 2 / 94 / 1 every 4km
Otago / 1220 / 1 / 78 / 15 / 100 / 5 / 98 / 1 every 2km
Southland / 713 / 0 / 82 / 11 / 100 / 6 / 94 / 1 every 2km
NZ / 10187 / 5% / 72% / 20% / 98% / 13% / 96% / 1 every 2km
8.Why is a 5-star road safer than a 1-star road?
4 or 5-star roads are ones that provide a more ‘forgiving’ safety environment than 1 or 2-star roads.
1 star – The least safe roads. These are most likely to feature severe roadside conditions such as trees, power poles and ditches. Likely to be undivided, have narrow lanes and shoulders, include a high frequency of major intersections, and have poor alignment and mountainous terrain.
2 star - These roads will again be typically undivided and will have major deficiencies in road features such as poor roadside conditions and/or many minor deficiencies such as insufficient overtaking provision, narrow lanes, and/or poorly designed intersections at regular intervals. Any divided 2-star road would have major deficiencies such as poor alignment, poor roadside conditions and poorly designed intersections at regular intervals.
3 star - Typically 3-star roads will be undivided and have deficiencies in some road features such as alignment and roadsides and/or poorly designed intersections at regular intervals. A divided 3-star road would have deficiencies in some road features such as poorly designed intersections at regular intervals.
4 star - These roads are typically divided but have minor deficiencies in some road features such as shoulder width or roadside hazards. Divided 4-star roads are very safe roads with a good safety performance. Undivided 4-star roads are straight with good overtaking provision, feature good delineation and safe roadsides. Typically an undivided 4-star road will not have high traffic volumes.
5 star - The safest of roads. 5-star roads must be divided, have grade separated intersections, good alignment, wide road shoulders, safe roadsides and excellent delineation. Roads with any at-grade intersections, or those that are undivided, cannot achieve a 5-star rating.
- Why don’t we have any 5-star roads in New Zealand?
We presently don’t have any 5-star roads in New Zealand, but we have sections of 5-star roads. A 5-star road is the ultimate ideal. To achieve this, the road must have a higher degree of safety built-in.
Due to New Zealand’s terrain it is often difficult to have straight roads and roadsides completely trafficable and free of obstacles. We typically use roadside barriers to protect roadside hazards, which although are much safer than nothing, the barriers are themselves sometimes a slight hazard and hence prevent a 5-star rating. Cut barriers and at-grade intersections have a similar effect on reducing the Star Rating.
Australia also does not have any 5 kilometre sections of 5-star roads.
10.Will we be aiming for 5-star roads?
A 5-star road is straight with good line-marking, wide lanes and sealed shoulders, clear, trafficable roadsides and overpasses or underpasses at intersections. This is often difficult to achieve on many of our roads due to the terrain and in many cases would not be economic. Research has indicated that a very good 4-star road is nearly as safe as a 5-star road as it provides a good level of safety protection, and the extra cost to achieve a 5-star rating may not be cost effective, or a good use of money unless traffic volumes were very high.
Typically moving a 2-star road to a 3 or a 3 to a 4-star will have the biggest road safety benefit and reduction in crash rates – dependent on the nature of traffic on the route and the vehicle kilometres travelled. You can view the estimated crash rates of each star rating in the next graph (based on traffic volumes).
Expected Crash Rates Associated with Each Star Rating
11.Are roads that carry a lot of traffic more likely to get a poor Star Rating?
Not necessarily. Traffic volumes influence some aspects of the Star Ratings. For example, overtaking provision and head-on risk is broadly determined with the amount of traffic on a road — generally overtaking demand increases as traffic volumes increase. However, a road carrying lots of traffic without a median barrier is likely to only have a 2 or 3-star rating even if other safety features are of a good standard. Many other factors, like the influence of lane widths on crash risk, do not depend on traffic volumes.
12.What safety interventions could make roads safer?
The NZTA is always looking at improving the safety of state highways and is committed to implementing innovative and comprehensive safety solutions.
Examples of safety measures include:
•improved markings, signage and lighting
•greater use of rumble strips
•roadside hazard removal or protection
•greater median space or median barriers on high volume roads
•improved overtaking opportunities
•intersection improvements where possible.
- Does the star rating take into account the road's speed limit and volume of traffic?
The KiwiRAP model presently only rates roads and the roadside environment. The speed limit is used in conjunction with curvature and crossfall data to determine speed environment. Speed environment is then used to help determine how safe the horizontal alignment of a road is i.e. a well designed windy section of road (with a low speed environment) may be safer than a straight section of road followed by a sharp (unexpected) curve.
Traffic volume is used to reflect the fact that on undivided roads the proportion of head-on crashes increases with increasing traffic volume, and that intersections with high volume side roads have a greater risk associated with them than those with low volume side roads.
14.How important are the roads in road safety?
Safer Journeys: New Zealand’s road safety strategy 2010-2020 introduces a Safe System approach to New Zealand. The Safe System differs from traditional approaches to road safety and seeks to improve safety across the road system. Rather than just blaming the road user for causing a crash, it acknowledges that even responsible people sometimes make mistakes in their use of the roads.
To do this, the Safe System has the objectives to:
•make the road transport system more accommodating and protecting of human error
•manage the forces that injure people in a crash to a level the human body can tolerate without serious injury
•minimise the level of unsafe road user behaviour.
To get to a Safe System we need to achieve:
•safe roads and roadsides – that are predictable and forgiving of mistakes. Their design should encourage appropriate road user behaviour and safe speeds
•safe speeds – that suit the function and level of safety of the road. Road users understand and comply with speed limits and drive to the conditions
•safe vehicles – that help prevent crashes and protect road users from crash forces that cause death or serious injury
•safe road use – ensuring road users are skilled and competent, alert and unimpaired. That people comply with road rules, choose safer vehicles, take steps to improve safety, and demand safety improvements.
- How does KiwiRAP align with Safer Journeys?
The KiwiRAP programme is very well aligned with Safer Journeys through:
•the high priority area of Safer Roads & Roadsides
•the key initiative of focusing efforts on high-risk rural routes
•the focus on Safer Road Use through informing motorists of relative risks.
KiwiRAP is a good example of the Safe System approach in action. Although Star Ratings data is about analysing and improving the roads, the Star Ratings will also empower road users to understand the risk on particular roads and what elements make up those risks. They can then adjust their driving behaviour for the conditions they see.
16.Should I take more risks on a 4 or 5-star road?
No. While some safety features of a road are more likely reduce your risk of a crash, and increase your chances of surviving if a crash does occur, they don’t make you indestructible. Safety features won’t necessarily save someone from death or serious injury, particularly if they’re speeding or not wearing a safety belt.
17.Aren’t most crashes caused by bad drivers?
Many crashes happen when everyday drivers make simple mistakes. Sober and responsible drivers obeying the speed limit and wearing seat belts frequently die on New Zealand roads. Safer roads minimise the chances of a crash, or if a crash does occur, the severity of the crash. Safer roads act as a safety net for when we make a mistake – which most drivers will do at some point.
However, this does not reduce the need for continuing education programs to minimise driver mistakes and improve driver safety. A Safe System approach doesn’t take the road user out of the picture or ignore their responsibilities. Instead of simply apportioning the majority of blame on the road user, the Safe System approach recognises the need for shared responsibility between transport system designers (i.e. road and vehicle engineers) and road users.
18.Why not just reduce the speed limit to improve safety?
Travel speed influences the severity of a crash and the risk of a crash occurring. However, speed limits are just one part of the road safety equation – the Safe System. There are many improvements that can be made to roads to make them safe, such as installing safety fences around roadside hazards.
Speed and safety need not be mutually exclusive. Some of Europe’s fastest roads are their safest. However, there maybe some instances where lowering the speed limit on a high risk, low star rated road may be an appropriate method of managing road safety outcomes, at least until the improvements are made.