iRAP Star Rating - a joint service from TRL & Gaist

The primary purpose of the iRAP model is to identify the financially attainable infrastructure upgrades that will allow a local network operator to proactively fix a road before casualties are caused by its design. Using existing Gaist imagery in the iRAP model can save time, effort and money to produce safer road investment plans (SRIPS). Both the iRAP assessment service and the highways improvements it recommends are suitable for grant funding.

A road safety audit to meet all obligations

It’s a fact: the casualty rate is 6.8 times greater on ‘local’ roads than on motorways.

Local Authorities have an obligation under the Road Safety Act of 1988 to conduct regular safety audits across their networks, be they on dual carriageways, in towns and cities, or on undivided rural roads.

Many councils have also pledged to support the targets in the UN Global Plan for the Decade of Action for Road Safety 2021-2030 to design new roads and upgrade existing roads to 3- Star Rating or better.

Proactively safer roads by design

A road used to be considered “safe” based on its crash history. As the volume of killed and seriously injured (KSI) road users has reduced in the UK, so this data becomes less helpful as an indicator of road safety. The modern approach to road safety considers physical risk management for ALL road users. iRAP models whole routes, not just black spots, across network boundaries, to provide a holistic assessment of risk and recommended mitigations. The model considers the needs of ALL travel modes and is also sensitive to speed and flows of road users when calculating the risks.

About iRAP

The International Road Assessment Programme is an international charity with a vision for a world free of high-risk roads. 

Active in 100+ countries, it provides the tools and training to road authorities, mobility clubs, development banks, industry and road safety stakeholders to make roads safer.

iRAP is an infrastructure safety management system, a core pillar of a Safe Systems approach to road safety. Research shows that a person’s risk of death or serious injury is approximately halved for each incremental improvement in Star Rating.

Applying the iRAP model initially involves surveying the road network by capturing video footage of the pavement. The model contains 50+ key safety critical road features which are ‘coded’ according to the risk they pose to different types of road users. The model identifies the features in the images and calculates the risk for every 100m section of route. This risk score is translated into a colour coded Star Rating which goes from 1 Star (black), which represents very high risk, through to 5 Stars (green) which is very safe. The lower the risk score, the higher the Star Rating.

As Local Authorities work to re-prioritise road use in favour of active travel modes, the Star Rating, and predicted reductions in casualties on their roads is a key piece of evidence to unlock funding from Active Travel England for road safety improvements.

A unique joint service: costed £ per mile

The actual cost per mile depends on the availability of imagery of the route to be assessed.

Significant savings are achievable when re-using existing Gaist image data, either data that has previously been captured for a different purpose, or data that has been captured by Gaist and is sitting – unused – in its data bank.

This iRAP service from TRL and Gaist is suitable for funding by Active Travel England.

A unique service: compelling evidence for investment

Outputs from the modelling result in evidence suitable for budgeting and funding applications:

  • The Star Rating is initially presented as a high level map which indicates the general risk state of road sections in a simple visual format.
  • The iRAP model then generates a range of countermeasures, along with their economic viability, which form the basis of a Safer Roads Investment Plan (SRIP) 
  • The iRAP model also automatically links improvement programmes to estimated reductions in Killed/Seriously Injured casualties. This makes it simple to compare and contrast the impact of interventions. 
  • Predicted change in Star Rating: Based on the selected mitigations, the sections identified for improvement are scored for their contribution to upgrading the Star Rating. This is where training is essential to understand how the model works and apply local knowledge, balanced with policy needs and budget restraints to find the most robust combination.  

A unique service: unique talents

Affordable imagery from Gaist Solutions: Gaist operates a panaromic, high-resolution image capture system that creates a visual record of the features contained within the roadscape. Wherever the Gaist survey vehicles go, the cameras are always on. After collecting data for a decade, Gaist believe they have 1/3rd of all local network roads already “in the bank”. Local authorities may have already commissioned a visual survey for another purpose and can re-use the same data for iRAP.

Gaist’s survey system has many advantages over a dash cam solution:

  • Gaist cameras produce constantly clear footage regardless of light levels or speed.
  • A single frame of footage retains its high resolution / high fidelity.
  • Gaist’s 360 degree camera allows the user to view and understand the complete context of any location.

TRL is the UK Centre of Excellence supporting users of the IRAP model. Training is provided as part of the service: awareness training can help people involved in road safety understand the basis for Star Rating and how to communicate about it clearly; more technical training is provided for users of the model to better understand the data inputs and the model outputs.

The Road Safety Foundation (RSF) is the license holder for the iRAP Star Rating model in the UK and provides quality assurance that iRAP projects are implemented properly. The RSF runs an iRAP User Group to provide a forum for exchange of best practice, a place to share challenges and help each other overcome them.  

Client references

National Highways undertakes an iRAP Star Rating assessment every 5 years. Recently published results showed the performance indicator for 90% of travel to be on 3-star or better roads by 2020 was surpassed, with 96% achieved. National Highways is using the iRAP approach throughout the organisation for strategic planning of investment, for prioritisation of routes to be treated, to help analyse routes and determine the best return options, and to ensure new designs are as safe as they can be.

TRL are currently delivering iRAP for the state of Himachal Pradesh, India. This two-year project involves modelling iRAP Star Rating on 9,000km of roads.

Route 55 in the State of Qatar used iRAP Star Rating to improve its safety from 2 to 4 Star.


Download further details of this service in this booklet. 

Watch a short presentation about the joint service here: 




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