Thanks to the efforts of our partners worldwide, iRAP’s Star Rating Methodology has underpinned road safety assessments in more than 140 countries, informing 3-Star or better road upgrades that are transforming journeys for pedestrians, bicyclists, motorcyclists and vehicle occupants across the world.

Now, informed by the latest global evidence on crash risk, iRAP’s current Star Rating model (version 3.02) is being updated. The new model (version 3.10), guided by experts and world-leading road safety research, will come online in May 2026 and be accessible via iRAP’s online platform, ViDA.

Find out more information here

To help you understand the changes, we have released:

iRAP Star Rating Model Update Explainer Note: Details the changes made to the crash risk models, risk factors and coding guidance.
iRAP Methodology Reference Guide: This consolidated reference guide fully describes the iRAP models and risk factors, as well as the evidence which underpins these.
Frequently Asked Questions (FAQ): Answers to common technical and data management queries.

In coming months, iRAP will release specification documents for version 3.10, including updated versions of the Upload File Specification, iRAP Coding Manual and the iRAP Star Rating and Investment Planning Manual.

Ahead of the May launch, we recommend that you review the documentation provided.

We will be providing regular communications in the lead-up to launch of the model update to ensure you are fully prepared for the transition.

ViDA users will be notified by email about the launch of version 3.10 in ViDA.

For support with ongoing projects or data management, please contact support@irap.org.

Current iRAP Methodology fact sheets

The iRAP Methodology fact sheets answer many of the questions people have about the iRAP approach, covering topics such as crash types, Star Rating Score equations, model calibration and estimation of economic benefits and costs. These fact sheets complement the Road Attribute Risk Factor fact sheets.

The ‘iRAP Methodology’ fact sheets describe the Star Rating and Safer Roads Investment Plan methodologies, while the ‘iRAP Road Attribute Risk Factors’ fact sheets describe the risk factors used in the models.

Fact Sheet 1: Overview

Provides an overview of the Star Rating and Safer Roads Investment Plan processes and a list of fact sheets in the series.

Fact Sheet 2: Development History

Provides an overview of the Star Rating and Safer Roads Investment Plan development history.

Fact Sheet 2a: Model Versions

Provides an overview of Star Ratings and Safer Roads Investment Plan model version management.

Fact Sheet 3: Road Attributes

Lists the road attributes included in iRAP assessments.

Fact Sheet 4: Crash Types

Provides an overview of the road users, crash types and crash initiation modes used in the models.

Fact Sheet 5: External Flow & Median Traversability

Describes External Flow Influence factors.

Fact Sheet 6: Star Rating Score Equations

Describes the iRAP Star Rating Score equations.

Fact Sheet 7: Star Rating Bands

Describes the Star Rating bands and how they were set.

Fact Sheet 8: Smoothed Star Ratings

Provides an overview of the process used to smooth Star Ratings.

Fact Sheet 9: Star Rating Worked Example

Includes a worked example of the way in which Star Ratings are calculated.

Fact Sheet 10: Casualty Estimation & Calibration

Describes how the number of casualties is estimated and models are calibrated.

Fact Sheet 11: Countermeasures

Describes the road safety countermeasures used in the methodology.

Fact Sheet 12: Multiple Countermeasures

Describes how the effectiveness of a countermeasure is estimated when used with others.

Fact Sheet 13: Economic Analysis

Describes the economic analysis used to prioritise countermeasure options.

Fact Sheet 14: Star Ratings for Schools

Describes the background research and development associated with the Star Rating for Schools methodology.

Fact Sheet 15: Model Localisation

This factsheet provides an overview of the functionality provided to localise the Star Rating and Safer Roads Investment Plans.

iRAP Road Attribute Risk Factors

Fact Sheet: Centreline Rumble Strips

Describes the road attribute risk factors used in the iRAP methodology for Centreline Rumble Strips.

Fact Sheet: Curvature

Describes the road attribute risk factors used in the iRAP methodology for Curvature.

Fact Sheet: Delineation

Describes the road attribute risk factors used in the iRAP methodology for Delineation.

Fact Sheet: Facilities for Bicycles

Describes the road attribute risk factors used in the iRAP methodology for Facilities for Bicycles.

Fact Sheet: Facilities for Motorcycles

Describes the road attribute risk factors used in the iRAP methodology for Facilities for Motorcycles.

Fact Sheet: Grade

Describes the road attribute risk factors used in the iRAP methodology for Grade.

Fact Sheet: Intersection Type

Describes the road attribute risk factors used in the iRAP methodology for Intersection Type.

Fact Sheet: Intersection Channelisation

Describes the road attribute risk factors used in the iRAP methodology for Intersection Channelisation.

Fact Sheet: Intersection Quality

Describes the road attribute risk factors used in the iRAP methodology for Intersection Quality.

Fact Sheet: Lane Width

Describes the road attribute risk factors used in the iRAP methodology for Lane Width.

Fact Sheet: Median Type

Describes the road attribute risk factors used in the iRAP methodology for Median Type.

Fact Sheet: Number of Lanes

Describes the road attribute risk factors used in the iRAP methodology for Number of Lanes.

Fact Sheet: Operating Speed

Describes the road attribute risk factors used in the iRAP methodology for Operating Speed and Mean Speed.

Fact Sheet: Paved Shoulder Width

Describes the road attribute risk factors used in the iRAP methodology for Paved Shoulder Width.

Fact Sheet: Pedestrian Crossing Facilities

Describes the road attribute risk factors used in the iRAP methodology for Pedestrian Crossing Facilities.

Fact Sheet: Pedestrian Crossing Quality

Describes the road attribute risk factors used in the iRAP methodology for Pedestrian Crossing Quality.

Fact Sheet: Pedestrian Fencing

Describes the road attribute risk factors used in the iRAP methodology for Pedestrian Fencing.

Fact Sheet: Property Access Points

Describes the road attribute risk factors used in the iRAP methodology for Property Access Points.

Fact Sheet: Quality of Curve

Describes the road attribute risk factors used in the iRAP methodology for Quality of Curve.

Fact Sheet: Road Condition

Describes the road attribute risk factors used in the iRAP methodology for Road Condition.

Fact Sheet: Roadside Severity – Object

Describes the road attribute risk factors used in the iRAP methodology for Roadside Severity – Object.

Fact Sheet: Roadside Severity – Distance

Describes the road attribute risk factors used in the iRAP methodology for Roadside Severity – Distance.

Fact Sheet: School Zone Warning

Covers the range of advance warning provided for schools.

Fact Sheet: Service Road

Describes the road attribute risk factors used in the iRAP methodology for Service Road.

Fact Sheet: Shoulder Rumble Strips

Describes the road attribute risk factors used in the iRAP methodology for Shoulder Rumble Strips.

Fact Sheet: Sidewalk Provision

Describes the road attribute risk factors used in the iRAP methodology for Sidewalk Provision.

Fact Sheet: Sight Distance Restriction

Describes the road attribute risk factors used in the iRAP methodology for Sight Distance Restriction.

Fact Sheet: Skid Resistance / Grip

Describes the road attribute risk factors used in the iRAP methodology for Skid Resistance/Grip.

Fact Sheet: Speed Management / Traffic Calming

Describes the road attribute risk factors used in the iRAP methodology for Speed Management/ Traffic Calming.

Fact Sheet: Street Lighting

Describes the road attribute risk factors used in the iRAP methodology for Street Lighting.

Fact Sheet: Vehicle Parking

Describes the road attribute risk factors used in the iRAP methodology for Vehicle Parking.

Fact Sheet: Full Reference List

Provides a complete list of citations used in the selection of iRAP road attribute risk factors.

Current iRAP Methodology fact sheets

iRAP Road Attribute Risk Factors

Model Updates