A variety of tools and approaches are available to assist in the delivery of infrastructure safety management. As with guidelines, some tools have been prepared for use at the global, regional or country level. In some cases, the tools developed in one location or country can be adapted for use in another, but extreme care needs to be taken to ensure that the new context is considered when doing this. The types of tools available for road safety infrastructure management are mentioned in brief here, with further details provided in other relevant sections of this manual.
Schermers et al. (2011) provides a useful summary of tools used in Europe (most of which are discussed in this document. Elvik (2011) suggests a framework for applying tools that are related to the stages of a road’s life cycle. The US has also developed a comprehensive suite of tools for road safety infrastructure management. These are briefly discussed in the example in Box 9.7
The Network Screening Tool identifies sites with potential for safety improvements through algorithms that identify areas of concern (e.g. higher than expected crash frequencies). In addition, high crash severities or a higher than expected rate of specific collision types can also be identified. These algorithms are effective for spot locations, as well as short and extended road segments.
The Diagnosis Tool identifies the nature of safety problems at specific sites. It is able to generate a range of data, including crash summary statistics, collision diagrams, collision pattern identification (including whether or not a collision type occurs at a higher than expected rate), and to conduct statistical tests for specific sites. Both engineering and human factors are integrated to identify safety concerns.
The Countermeasure Selection Tool helps in the selection of interventions to reduce crash frequency and severity at sites. This tool incorporates site-specific countermeasures that are recommended based on the site type, crash patterns, and specific safety concerns identified with the earlier Diagnosis Tool. Single or multiple countermeasures may be selected and appraised with the Economic Appraisal and Priority Ranking tools.
The Economic Appraisal Tool performs an appraisal of either specific countermeasures or different options at a site. Within this tool, a number of economic evaluations can be undertaken, including cost-effectiveness, benefit-cost ratio and net benefits. Safety-effectiveness is estimated via observed, expected and predicted crash frequency and crash severity, as well as crash patterns and expected crash reduction for specific countermeasures. Notably, the analysis results are consistent with requirements of the Federal Highway Safety Improvement Programme guidelines.
The Priority Ranking Tool ranks sites and proposed improvements according to the benefit and cost analysis conducted by the Economic Appraisal tool. The site and improvement rankings are determined through comparison of cost-effectiveness, benefit-cost ratio, net benefits, safety benefits, construction cost, number of total crashes reduced, fatal and severe injury crash reduction, and fatal and all injury crash reduction. The Priority Ranking Tool assists in the optimisation of projects and maximisation of benefits across sites.
The Countermeasure Evaluation Tool allows pre- and post-evaluations of safety improvements using the Empirical Bayes (EB) approach. In addition, this tool has the capability to evaluate changes in the proportion of collision types. Analyses can also be performed to evaluate the efficacy of individual or combined countermeasures and construction projects. A benefit-cost analysis is also available to assess the economic benefits of countermeasures or construction projects.
Further details on these tools can be found at: http://www.safetyanalyst.org/.
The tools identified in Box 9.7 follow the broad stages of infrastructure safety management identified in Introduction. Later chapters discuss each of the key tools. The tools referenced for different stages of road safety management include:
— Crash data: Establishing and Maintaining Crash Data Systems. discusses the establishment and use of crash data systems, and some of the useful tools that are desirable for such systems.
— Non-crash data: Non-Crash Data and Recording Systems. discusses non-crash data, including the need for systems to collect and analyse such information.
— crash-based identification (Crash-based Indentification (‘Reactive Approaches’))
— road safety impact assessment (Road Safety Impact Assessment in Proactive Identification)
— road safety audit (Road Safety Audit in Proactive Identification)
— road safety inspection (Road Safety Inspection in Proactive Identification)
— road assessment programmes (Road Assessment for Safety Infrastructure in Proactive Identification).
A further example, this one from France can be seen in Box 9.8.
A Road Safety Impact Assessment is carried out for all infrastructure projects at the initial planning stage before the infrastructure project is approved. It identifies the road safety considerations which contribute to the selection of the proposed solution and provides all relevant information necessary for a cost-benefit analysis of the different options assessed.
A Road Safety Audit of the design characteristics from a safety viewpoint is carried out for all infrastructure projects by a trained auditor or a team of auditors. Audits form an integral part of the design process of the infrastructure project and are carried out at different stages of the project: draft and detailed design, pre-opening and early operation. Where unsafe features are identified in the course of the audit, the design is rectified. When it is not rectified before the end of the appropriate stage, the reasons are stated by the authority in an annex of the report.
Source: Road Safety Audits (Sétra , 2012)
A Road Safety Inspection is carried out on the national road network for all existing roads in order to report on the details of the road, its surrounding area and the general environment that can influence the user’s behaviour or affect their passive safety and thus have repercussions on road safety. The concept is to provide a method that will help the operator to improve their network knowledge. Inspection visits are made by appropriately qualified personnel, to identify the main road safety issues, and to provide a fresh point of view on the system. The systematic inspection of a section of road thus consists of a quick and practical rating of the main configurations that may not be expected by the road user, considering all modes of transport.
Source: ISRI Initiative: road safety inspections of routes (Sétra, 2008).
Safety of users on existing roads: this approach, called SURE in France, is carried out on the national road network for all existing roads. It is a general method of which the main innovation is to explicitly and continuously provide a complete approach of road safety improvements, from the road safety issues study to the assessment stage via the implementation of treatments. The aim of this approach is to determine and implement adapted treatments for sections of road where the safety gain is potentially higher.
The SURE process is a practical application of the common road safety approach presented in Examples of Infrastructure Policies, Standards and Guidelines in Policies, Standarts and Guidelines
All of these tools can (and should) be used in parallel. Each is useful for different purposes, and for different stages of infrastructure safety management. Strengths and weaknesses are discussed in later chapters. Historically, the collection and analysis of crash data has been the most widely applied approach to managing safety. This is likely to continue to be an important approach, and is an important starting point for those in LMICs. Road safety audit and safety inspection are other widely applied tools, including in LMICs. One added advantage of these approaches is that they are a useful mechanism to improve safety culture.
One often over-looked issue is that the earlier within the safety management process, or project development process, the greater the potential to make a cost-effective improvement in safety outcomes. This is best demonstrated in the planning and development phase. In many countries road safety practitioners have historically relied upon road safety audit to determine safety issues in planning and development stages of design. In more recent times, tools to assist in embedding safety into design at the earliest stages have been developed. Importantly, some of these are aimed at practitioners who are not from a safety background in an attempt to include safety considerations into decision-making. These tools can be either quantitative in approach (such as tools that are based on crash prediction models) or qualitative. One of the most widely applied quantitative models is the US Interactive Highway Safety Design Model (IHSDM). This includes several modules, some of which can be used at the project development stage (AASHTO, 2010). It should be noted that this tool is generally applied to existing roads in the US, as very few new roads are built. Further information on IHSDM can be found in Box 9.10 and in Proactive Identification.
iRAP has also been used to quantify safety implications at the early design stage (see the case study in Box 9.9).
The solution: The iRAP star rating has been used in a number of countries to help improve design in order to achieve better safety outcomes. Examples include a pilot project in Moldova (the M2-R7 corridor – 116 km) and in India on the Karnataka State Highway Improvement Project (550 km). The projects were supported by the Millennium Challenge Corporation and the Global Road Safety Facility, respectively, as well as local and international partners.
Information was drawn from the road design plans prior to construction or rehabilitation to rate the safety of the proposed design. The iRAP star ratings score how road infrastructure influences the likelihood of crashes occurring and the severity of the crashes that do occur. The approach provides a simple and objective measure of the relative level of risk associated with road infrastructure for the movements and manoeuvres that road users make. Different design options are compared, and the likely safety outcomes of different designs determined.
The outcome: The roads in Moldova and India show substantial improvements in safety based on the final designs implemented, notably for pedestrians in villages. Final designs for construction are anticipated to provide a reduction in severe injuries of 40% per year in Moldova and 45% in India. On the larger, busier, Indian network, this approximates to saving more than 100 deaths per year.
A fuller account of the project in India is available in Rogers et al., 2012.
The road assessment identified the need for pedestrian facilities and improved pedestrian safety. Following the assessment, provision for pedestrians was added to the design (including crossings, median refuge islands and sidewalks) and measures were included to slow traffic.
Source: Case study provided by iRAP
The solution: ITD used the Federal Highway Administration (FHWA) IHSDM software for this study. The IHSDM software is a package of analysis tools to evaluate the safety and operation of geometric design decisions on highways, and predict crashes based on the AASHTO Highway Safety Manual methodologies. The advantage of using the IHSDM provided the opportunity to perform a detailed review within the corridor on a number of critical elements at the same time (i.e. traffic operations, geometry and safety) to identify and target potential problem areas and develop effective mitigation strategies. Data requirements included crash data, existing roadway design plans, video, traffic control information, and traffic volumes (existing and projected). Information on expected crash reduction was used to compare effects of alternative treatment options. The list of mitigation strategies developed to address the identified issues was evaluated and prioritized.
The outcome: From the IHSDM output, ITD found more than half of the 11-mile corridor experienced a crash rate higher than the statewide average. The IHSDM Policy Review and Crash Prediction modules resulted in identifying geometric deficiencies, specific locations requiring further investigation, areas that required design improvements and safety issues on the corridor. A Corridor Plan Report was prepared which summarised the review, analysis and recommendations to be considered for potential improvement projects and programmed for implementation by the ITD over the next 10 years. Recommended mitigation measures consisted of passing lanes, intersection capacity improvements, sight distance improvements, roadside safety enhancements, intelligent transportation systems (ITS), animal crossings, and access management strategies.
Further information can be found on the FHWA website (http://safety.fhwa.dot.gov/hsm/casestudies/id_cstd.pdf).
Source: FHWA, 2015.
The Strategic Tool for Assessment of Road Safety (STARS), developed in Australia, relies on checklists to help identify negative safety outcomes (Jurewicz, 2009). This approach provides a risk value to each of the checklist questions, and ultimately an overall safety rating for the planned project. Checklists are available for different stages of development, including regional or structure plans, master plans, sub-division or neighbourhood plans, arterial corridors, and new/commercial developments. Example road safety planning issues at the regional level include:
Further information on safety assessment prior to a road safety audit can be found in Road Safety Impact Assessment in Proactive Identification.
Road safety management tools need constant review as good practice and new approaches emerge. Elvik (2011) conducted such a review of European infrastructure safety management tools, and despite the many years of development and experience in using such tools, a number of opportunities for improvement were identified. Some of the key findings were that: