This factsheet is part of a series that describes the iRAP methodology. It provides an overview of the Star Rating and Safer Roads Investment Plan development history.

Related documents

This factsheet should be read in conjunction with:

• • - Other factsheets in the iRAP Methodology Fact Sheet
  • - iRAP Road Attribute Risk Factor Fact Sheets.
  • - Road Safety Toolkit.

EuroRAP Star Rating model

The iRAP models used today are the result of more than a decade of development work, which began with EuroRAP (http://www.eurorap.org) in 1999. The EuroRAP model was based on assessments of road attributes, such as safety barriers, that afford protection to car occupants in the event of a crash. The equations and risk factors used in the EuroRAP model were developed by a working group comprising representatives of the (then) Swedish National Road Administration, the Dutch Ministry of Transport, National Roads Authority, Republic of Ireland, Transport Research Laboratory (TRL) and with contributions from the English Highways Agency, Germany federal research agency, BASt, and engineers and analysts from leading European motoring organisations and EuroRAP staff. The development drew heavily on the work of Elvik and Vaa (2004) and Elvik et al (2009) and is described by Lynam (2012).

The EuroRAP model was used over the period 2004-10 to assess roads, initially in Sweden and Germany, then in 10 countries by 2011 to produce The European Road Safety Atlas (http://atlas.eurorap.org). EuroRAP began using the ‘version 2.2’ of the iRAP vehicle occupant Star Rating model in 2010 and ‘version 3’ of the iRAP model in 2012 (see below).

AusRAP Star Rating model

The AusRAP (http://www.ausrap.org) model was based on assessments of road attributes that affect both the likelihood that a crash will occur (such as delineation) and those that provide protection in the event of a crash (such as safety barriers). Like the EuroRAP model, the focus was on car occupants. The equations and risk factors used in the AusRAP model, which was developed for the Australian Automobile Association (AAA) by ARRB Group, drew on both the EuroRAP work and research undertaken by ARRB Group for Austroads.

The AusRAP model was used over the period 2006 to 2008 to assess more than 20,000km of national highways and more than 5,000km of State highways. AusRAP began using the iRAP ‘version 3’ models in 2012 (see below).

iRAP Star Rating and Safer Roads Investment Plan models

Following the release of the World Report on road traffic injury prevention (WHO, 2004), the urgent need for decision support tools in low and middle-income countries was recognised. The FIA Foundation approached the established Road Assessment Programmes with the challenge to adapt the RAP approach to meet the needs and data availability of low- and middle income countries. The iRAP models were first derived in 2006 from the EuroRAP and AusRAP models by leading researchers at TRL (United Kingdom), ARRB Group (Australia) and MRI Global (United States) with technical support from the World Bank Global Road Safety Facility. The models were collectively designated ‘version 2.1’, acknowledging that their development had built heavily on earlier ‘version 1’ EuroRAP and AusRAP models. The version 2.1 models significantly expanded on the EuroRAP and AusRAP models. In particular, they enabled:

* assessment of risk not just for vehicle occupants, but also motorcyclists, pedestrians and bicyclists.

* production of Safer Roads Investment Plans (SRIP) that identify economically viable countermeasures that can improve a road’s Star Rating and reduce risk of death and serious injury.

The iRAP version 2.1 models were pilot tested in Chile, Malaysia, Peru and South Africa in 2006 and, with some refinement, resulted in the creation of the ‘version 2.2’ iRAP models. These version 2.2 models were subsequently used on a large-scale around the globe. For example, they were used:

* by governments, development banks and automobile associations between 2007 and 2012 to assess more than 50,000km of roads in 26 low- and middle-income countries.

* by usRAP (http://www.usrap.us) between 2009 and 2012 to assess almost 10,000km of roads in the United States.

* by EuroRAP and EuroRAP Members from 2008 to 2011, to bring the total road length assessed in Europe to 60,000km.

KiwiRAP Star Rating model

In parallel to the development and large-scale use of the iRAP version 2.2 models, the New Zealand Transport Agency (NZTA), the New Zealand Automobile Association (NZAA) and other local stakeholders collaborated with AusRAP to adapt the AusRAP model for use in New Zealand. The KiwiRAP (http://www.kiwirap.org.nz) model was used in 2010 to assess the more than 10,000km of the State Highway network.

Updated iRAP models

In 2009, iRAP began formally reviewing the version 2.2 models. ARRB Group and MRI Global were commissioned to review the risk factors and other elements used in the version 2.2 models (Turner et al, 2009). A meeting of experts was convened in 2010 at the request of the World Bank Global Road Safety Facility to review the model in the context of experience gained by its application around the world (iRAP, 2010a). The expert group also reviewed information that has since been published, such as Vehicle Speeds and the iRAP Protocols and the Crash Rate-Star Rating Comparison Paper (iRAP, 2010b; iRAP 2011). Overall, the experts group found that the model was “…impressive, comprehensive and systematic …” but also that there were areas for further development.

Drawing on the ARRB Group and MRI Global reviews and the outcomes of the experts meeting, the experience of countries and iRAP staff in using the models, and new research (particularly by Austroads in Australia and the Transportation Research Board (TRB) in the US), the first major update of the iRAP model was undertaken over a period of two-years. The key areas of focus were:

* The addition of new road attributes, such as street lighting and skid resistance.

* Adjustment of road attribute coding categories to better reflect underlying research. For example, the type of roadside hazard and the distance between the edge of the road and the hazard could be recorded.

* Providing for greater detail in the assessment and assumptions related to exposure (e.g. side road volumes and pedestrian flows).

* Updating the underlying methodology for calculating risk scores to better reflect real-world conditions, particularly for the balance between vehicle occupant crash types (e.g. head-on and run-off road crash proportions) and for pedestrian crash risk.

* Adapting the models so they could be used to ‘Star Rate’ road designs and meet the trend towards setting Star Rating-based performance targets, such as ‘increase the percentage of road rated 3-stars or  better.’

* Including the ability to account for multiple countermeasures at a single location and predict the likely Star Rating after an investment plan is implemented.

This process was led by iRAP staff with oversight by the Global Technical Committee (GTC), which includes experts from the leading road safety research organisations in the world. The work of the committee and research teams from around the world culminated in the model now named ‘Version 3’. This model was first put into application 2012. At time of writing this fact sheet, the version 3 model had been used to assess some 150,000km of roads.

References

Lynam, D (2012). Development of Risk Models for the Road Assessment Programme. RAP504.12 and TRL Report CPR1293, Published by iRAP and TRL and available at: http://www.trl.co.uk and at https://irap.org.
Turner, B., Affum, J., Tziotis, M. and Jurewicz, C. (2009). Review of iRAP Risk Parameters. ARRB Group Contract. Report for iRAP. http://irap.org/about-irap-3/research-and-technical-papers?download=111:review-of-irap-risk- parameters.
iRAP (2010a). The iRAP Model Review Workshop. http://irap.org/about-irap-3/research-and-technical- papers?download=42:irap-model-review-workshop.
iRAP (2010b). Vehicle Speeds and the iRAP Protocols. http://irap.org/about-irap-3/research-and-technical- papers?download=47:vehicle-speeds-and-the-irap-protocols.
iRAP (2011). Crash Rate-Star Rating Comparison Paper. http://irap.org/about-irap-3/research-and-technical- papers?download=40:crash-rate-star-rating-comparison-paper.
WHO (2004) World Report on road traffic injury prevention, World Health Organisation, Geneva

6 September 2013, © International Road Assessment Programme (iRAP) 2013.