EuroRAP provides three protocols for measuring and communicating road safety risk that can be applied to any country.
|Risk Mapping||Colour-coded maps showing the risk of death and serious injury that road-users face on different roads, based on historical crash data.|
|Performance Tracking||Uses risk mapping data to assess how risk on the network as a whole, and on individual roads, has changed over time.|
|Star Rating and Safer Roads Investment Plans||Star Ratings give a measure of the in-built safety of roads based on a proactive survey, Safer Roads Investment Plans provide suggested life saving treatments.|
Risk Maps are colour coded maps showing the risk of death and serious injury on individual road sections across a road network. Typically, national programmes map higher tier roads first developing the network to the regional level over time. EuroRAP mapping concentrates on rural roads outside major towns and cities, with an emphasis on route safety rather than crash cluster sites or black spots.
Road networks are aggregated into sections where they fall along the same numbered road, the design and operation of the road is uniform and where the start and end points are meaningful. Crash and traffic flow are assigned to each section. Data are compiled into three year periods to give a robust estimate of risk.
Safety indicators based on the road network, crash numbers and traffic flow are used to produce different maps based on the target audience. For example:
- Risk per vehicle kilometre travelled: Aimed at individual road users, this measure shows how and where behaviour needs to be modified to minimise risk and, in doing so, enable users to recognise the sources of risk on different types of road
- Risk per kilometre: Aimed at road authorities, operators and policy makers this measure shows where the highest and lowest numbers of accidents occur on the network
- Potential crash savings: Shows the number of crashes that could be saved if risk rates on high-risk road sections were brought to the average. Used with cost information this can indicate locations with the highest returns on investment
Ratings on each of the maps are colour-coded into 5 levels of risk:
- Green: Low risk
- Yellow: Low-medium risk
- Orange: Medium risk
- Red: Medium-high risk
- Black: High risk
Performance Tracking uses the data compiled for each risk map to assess how risk on the network as a whole, and on individual road sections, has changed over time. The standard approach is to highlight those road sections that have shown an improvement over time (sections where there has been a significant reduction in the number of fatal and serious crashes between data periods), and those where there has been little or no change (so-called ‘persistently higher risk’ sections). A number of statistical filters are used to shortlist road sections.
Performance Tracking of road sections over time has several stages:
- Data are initially analysed to identify sections that have shown a reduction in the number of collisions over time and those where there has been little or no change
- Data for individual years is then checked to assess consistency of the patterns
- Highway authorities are asked for information on remedial, enforcement or education measures that have been implemented
In addition to giving authorities prior notice of the results and the opportunity to respond, pre-publication consultation is very important in building an understanding of a section’s characteristics, measures that may have been implemented during the data periods, measures planned in the immediate future, and any cost benefit estimates that may have been made.
The results can be used to benchmark performance on a national and local level but has proven particularly useful in comparing risk between countries across Europe and beyond.
STAR RATING AND SAFER ROADS INVESTMENT PLANS
Much as Euro NCAP tests Star Rate the in-built safety standard of new cars, Star Rating gives a measure of the in-built safety of roads. These ratings are based on road attribute data, and provide a simple and objective measure of the level of safety built in to the roads for vehicle occupants, motorcyclists, pedestrians and cyclists. Around 1 million kms of roads have now been surveyed using this methodology worldwide.
The Star Ratings reflect risk contributed by each of the road attributes that are coded – the higher the risk, the lower the rating. The risk is calculated using ‘crash modification factors’ that describe relationships between road attributes and crash risk. Star Rating information can be viewed using charts, tables and maps.
Increasing numbers of road authorities around the world are setting Star Ratings as policy targets. This approach can be attractive to senior officers and elected members who are accountable for ensuring that policies are being effective at the macro level, and that funds are well allocated. For example, Highways England has a delivery plan commitment to ensure that 90% of travel on the Strategic Road Network occurs on 3-star roads or better by 2020. Star Ratings can also be applied to designs. This can motivate designers of new and improved roads to think about risk management in a fresh way.
Safer Roads Investment Plans (SRIPs) identify ways in which fatal and serious injuries can be prevented in a cost-effective way. The ViDA software that prepares Star Ratings also calculates the casualty reduction that might be expected from implementing any of around 90 countermeasures individually or in logical combinations. The software examines every 100 m along an inspected road, comparing the value of crashes that might be saved against the cost of implementing a countermeasure. The software provides an economic appraisal of a Safer Road Investment Plan (SRIP). This SRIP can be interrogated at the individual section, region or national (portfolio) level to assess the appropriateness and effectiveness of individual options for improvement. SRIPs can be refined to allow economic appraisal of a locally acceptable treatment programme. The appraisal period is normally 20 years, allowing the cost of implementing each measure to be evaluated against the expected casualty savings over the economic life of the investment. ViDA provides present values (PVs) and Benefit to Cost Ratios (BCRs) for appraisal of each proposed countermeasure (ViDA is extensively documented at www.irap.org).