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Road Safety Infrastructure Management: Tools and Methods

Authors: Suzy Charman, John Barrell, Steve Lawson, James Bradford, Hans Vollpract, Michael Tziotis, Victoria Marlene Smith, Catherine Willis

1. Introduction and Aims

There are a variety of infrastructure safety management tools and methodologies that have been developed to help evaluate, prioritize and monitor road infrastructure safety performance; However, there are limited guidelines available that describe how and when each tool should be used in order to support a robust road safety infrastructure management system.

These guidelines outline the road safety management activities that are needed to deliver the recommendations in the Global Plan and the tools/methodologies that can be used.

This guideline has been developed to be applied across all road types, urban, semi-urban and rural and to be applicable to the safety of all road user groups. 

2. Safer Roads and Mobility Policy

Ensuring that the safety of road infrastructure is managed is a primary function of road authorities.  The following is a suggestion for minimum requirements for road safety management:

  • Review design options pre-feasibility stage to determine safety impact
  • Undertake independent Road Safety Audit on all new roads and schemes (irrespective of size) at (at a minimum):
    • One stage prior to construction of the road
    • One stage following construction of the road
  • Develop and follow Work Zone safety guidance
  • Monitor all new road schemes post opening
  • Identify the worst 10% of sites or sections across the network every year through the analysis of crash data (OR work with the Police to improve crash data so that this can be done) and develop targeted treatment programmes
  • Undertake proactive Road Safety Inspections at least every 5 years, follow up with detailed Road Safety Assessments of high priority sections
  • Undertake maintenance inspections at least every year
  • Evaluate treatments applied on existing roads to build an evidence base of what works, and what does not work
  • Pay attention to the needs of all road user groups that are at risk on the roads, in particular Vulnerable Road Users

3. Entry to Tool and Method Information by Activity

3.1 New Roads

Assess safety impact, costs and benefits of different options prior to scheme development

  • Road Safety Impact Assessment

Assess safety before, during and after construction of new roads and schemes

  • Road Safety Audit
  • Star Rating (iRAP) – New Roads and Schemes
  • WorkZone Safety Guidelines

Monitor and review safety of new roads once opened

  • Road Safety Audit (Post Opening)
  • Monitoring and Evaluation

3.2 Existing Roads

Identify damaged or missing infrastructure

  • Maintenance Inspections

Identify prioritysites for review and treatment (blackspots/hotspots/clusters)

  • Blackspot Analysis and Treatment

Identify priority road sections for review and treatment

  • Route/Corridor Analysisand Treatment
  • Star Rating (iRAP) – Existing Roads
  • Road Safety Inspection

Assess high priority sections in detail

  • Road Safety Assessment

Identify and treat network-wide emerging crash themes and trends

  • Network/Area Analysisand Treatment

Develop cost effective treatment plans

  • Economic Appraisal

Evaluate impact of treatments

  • Monitoring and Evaluation

4. Entry to Tool and Method Information by New/Existing and Proactive/Reactive Classification

 

New Roads

Existing Roads

Proactive approaches

Road Safety Impact Assessment

Road Safety Audit

Star Rating (iRAP) – New Roads and Schemes

WorkZone Safety Guidelines

Maintenance Inspections

Star Rating (iRAP) – Existing Roads

Road Safety Inspection

Reactive approaches

 

Blackspot Analysis and Treatment

Route/Corridor Analysis and Treatment

Network/Area Analysis and Treatment

Road Safety Assessment

 

Guidance is also provided on:

  • Economic Appraisal of Potential Solutions
  • Monitoring and Evaluation

5. Entry to Tool and Method Information by Tools and Method List

Blackspot Analysis and Treatment

Maintenance Inspections

Network/Area Analysis and Treatment

Road Safety Assessment

Road Safety Audit

Road Safety Impact Assessment

Road Safety Inspection

Route/Corridor Analysis and Treatment

Star Rating (iRAP) – Existing Roads

Star Rating (iRAP) – New Roads and Schemes

Work Zone Safety Guidelines

Economic Appraisal of Potential Solutions

Monitoring and Evaluation

6. Tools and Methods

6.1 Blackspot Analysis and Treatment

Fact Sheet: Blackspot Analysis and Treatment

Description

Blackspot analysis is concerned with identifying specific locations on the network where there is a concentration of crashes.  It is sometimes known as hazardous location analysis, crash cluster analysis or hotspot analysis.

Problem locations are identified by reviewing the crash history across the network and identifying locations which have higher crash occurrence than would otherwise be expected given the road character and features.

Whether a site constitutes a blackspot is based on very simple rules and definitions.  A site is usually considered as being a blackspot if there are greater than –x– crashes in a section or at a site of less than –y– length in –z– years within a distance of –a– metres.  These definitions need to be determined locally since patterns in crash reporting and occurrence vary greatly.

There are many methods to screen for blackspots, these include: crash density (nearest neighbour method), fixed radius method (crashes with the most neighbours), heat maps, fixed length method, or simple pin maps that give a visual indication of clusters. 

Once blackspots have been identified they are normally prioritised based on the application of weightings.  Often this means giving weightings to different severity crashes (e.g. Fatal=10, Serious=5, Slight=2, Damage Only=1 multiplied by the number of crashes of a given severity at a site to give a score). 

Crashes at the identified blackspot are analysed to identify common patterns that may relate to an underlying safety problem.  These analyses can be helped through the use of cross tabulations, stick analyses and crash diagrams.

High priority blackspots are then investigated through a site visit where a clear localised road defect and corresponding treatment can be determined.  Often treatments are very inexpensive.  This means that blackspot analysis and management can be a very cost effective way to improve road safety. 

Links and Guidance References

Existing Roads – Reactive Approaches manual produced by AfDB can be found at: www.afdb.org/en/documents/document/road-safety-manuals-for-africa-existing-roads-reactive-approaches-51936/

When to Apply and on What Road Types

Blackspot analyses should be undertaken annually.

If it is necessary to prioritise analysis due to budgetary or resource constraints, higher volume roads can be given priority.

Data and Software Requirements

Crash data with precise and accurate location information need to be recorded by the police and made available to engineers.

Some crash database programmes have analysis functionality that can help make the tasks of identifying blackspots and investigating their main characteristics using cross tabulations and stick analyses very straight forward.

Personnel Requirements

Data analyses can be undertaken by a member of staff with an engineering, mathematics or statistics background.  Though they would have the pre-requisite skills to undertake such analyses in a systematic manner, formal training is recommended.  

Once the initial analyses have been carried out, the site visits and assessment of potential remedial measures should be undertaken by experienced road safety engineers with similar qualifications to those described for Road Safety Audit. In particular they need to have undertaken basic training in collision investigation or road safety engineering.

Indicative Cost

Any significant costs are associated with ensuring crash data include precise locations.  Once these are established, costs are relatively low.

Common Issuesand Solutions

Blackspots are identified but there is no budget to treat them:

  • The cost of some treatments can be very small; some treatments can be combined into routine maintenance programmes at little or no extra cost
  • Undertaking Economic Appraisal or Cost Effectiveness analyses can help to make the business case for investment

Under-reporting of crashes makes identifying blackspots difficult:

  • Check ratio of fatal crashes to serious, slight and damage only crashes to assess the degree of under reporting
  • If poor levels of reporting, provide training to police and lobby for more complete data

Incomplete records or inaccurate records reduces reliability of blackspot analysis

  • Introduce mobile crash collection devices that allow checking for completeness as data are entered and cross checking for consistency of information
  • Introduce crash data systems that check for completeness and cross check for consistency of information
  • Training for police

Reliability of crash severities

  • Cross check against health/vital register data

Lack of precise information on crash locations

  • Introduce GPS devices for recording coordinates at the scene
  • Tablet/mobile devices to allow recording of accurate crash locations

Access to data

  • Data sharing protocols
  • Web-based database system

6.2 Maintenance Inspections

Fact Sheet: Maintenance Inspections

Description

Maintenance inspections for safety ordinarily address two main aspects:

  • Safety: Designed to identify all defects likely to have a safety impact.  Risk is assessed on site and the defect categorised to determine priority.  Defects may be damaged or missing signs/furniture.
  • Condition: Designed to identify deficiencies in the highway fabric which, if left untreated, would impact upon safety, performance and serviceability of the road.

These are undertaken on a routine basis to ensure that emerging defects are assessed.

Maintenance inspections should be undertaken according to an agreed protocol, manual or procedure.

Arrangements should be made to review the inspection, assessment and recording regime at intervals to consider:

  • Changes in network characteristics and use
  • Completeness and effectiveness of data collected
  • Effectiveness of data analysis
  • The need for changes to the inspection regime derived from risk assessment

Maintenance inspections are normally undertaken by a team in a slow moving vehicle, at frequencies that reflect the characteristics of the particular highway and its use. In busy urban areas, particularly when inspecting footways, it may be difficult to obtain the necessary level of accuracy from vehicle-based inspections and walking should be used. It would seem logical for cycle routes to be inspected by cycle, although inspection of parts of some shared routes may be possible by vehicle.

Condition surveys identify the current condition of the network and from this condition, both long-term and short-term maintenance funding decisions can be made. Repeatable condition surveys allow trend analysis to be used to confirm the original decisions or allow for changes as a result of the changing network condition.

Links and Guidance References

Well Maintained Highways – Code of Practice UK Roads Liaison Group can be found at: www.ukroadsliaisongroup.org/download.cfm/docid/C7214A5B-66E1-4994-AA7FBAC360DC5CC7

In UK all surveys are carried out in accordance with:

  • UKPMS Visual Survey Manual and Users Manual
  • Relevant sections of the Design Manual for Roads and Bridges and TRMM

When to Apply and on What Road Types

Maintenance inspections should be undertaken on all existing roads; at a greater frequency on those roads carrying higher traffic volumes.  The frequency of maintenance inspections will need to be determined locally, though it is recommended that, as a minimum, all roads should be subjected to maintenance inspections annually, with higher volume roads being inspected every month.

Data and Software Requirements

An asset register may be used by authorities to record all inventory on their network for which they have an associated liability. This register may be in electronic or paper format.

All information obtained from inspections and surveys, together with the nature of response, including nil returns, should be recorded consistently to facilitate analysis. Such analysis should enable the data from inspections to be reviewed independently, but also in conjunction with other survey information to enable a holistic view to be taken of maintenance condition and trends related to network characteristics and use.

Personnel Requirements

Maintenance inspections need to be undertaken by a minimum of two people, and where specialist equipment is used more team members may be required.

Training is especially important in the case of inspections and surveys where the quality and treatment of data could have significant legal and financial implications.

Some countries specify formal qualifications such as NVQs, SVQs and the City & Guilds 6033 Scheme in UK.

Indicative Cost

Costs vary significantly dependent upon the level and complexity of inspection being undertaken.

Common Issues and Solutions

Insufficient trained personnel:

  • Develop qualification and experience specifications for personnel
  • Develop training course for maintenance inspections

Insufficient budget:

  • Identify portion of maintenance budget to be applied to maintenance inspections
  • Determine costs and benefits of maintenance inspections in order to make the business case for investment

Deficits not addressed in a timely manner:

  • Develop formal requirements for follow up and rectification of different category deficits
  • Develop legal basis/requirement for follow up

Maintenance inspections not undertaken regularly:

  • Develop a schedule of required inspections for each road type

Consistency of application/quality issues:

  • Develop a maintenance inspection manual
  • Train personnel
  • Undertake an annual audit of inspection results
  • Ensure new staff are mentored/teamed up with experienced staff

6.3 Network/Area Analysis and Treatment

Fact Sheet: Network/Area Analysis and Treatment

Description

Area analysis can be applied where it is possible to identify common crash themes by area, often using a police area code.  In order for this to be successful the areas need to be relatively small and have a very high concentration of crashes. Therefore this approach lends itself to application to urban areas.  Identification of common crash types can help identify potential area-wide remedial treatments. 

The first step is to undertake a nation-wide analysis of crashes and their themes.  Then the same analyses can be undertaken by area.  This allows the analyst to determine if there are any patterns specific to that area in relation to the national situation.   This can be done using simple statistical tests such as Chi-Squared.

After the main crash themes of interest are identified for an area it is essential to visit that area and to identify potential treatment solutions.

Links and Guidance References

AfDB Existing Roads – Reactive Approaches manual can be found at: www.afdb.org/en/documents/document/road-safety-manuals-for-africa-existing-roads-reactive-approaches-51936/

When to Apply and on What Road Types

This approach can be used for all road types and it is particularly useful when accurate locations of crashes are not available.

The approach can be applied annually.

Data and Software Requirements

These analyses will require a minimum of three years of crash data.  In some countries with high rates of under reporting it may be necessary to use up to five years of data.  There is a balance to be reached between having sufficient data for the analyses to be robust and having data that reflects the current road network.

These analyses could potentially be performed using Microsoft Excel or similar, though more tailor-made analysis programmes could make the task more straightforward.

Personnel Requirements

Data analyses can be undertaken by a member of staff with an engineering, mathematics or statistics background. Though they would have the pre-requisite skills to undertake such analyses in a systematic manner, formal training is recommended.  

Once the initial analyses have been carried out, the site visits and assessment of potential remedial measures should be undertaken by experienced road safety engineers with similar qualifications to those described for Road Safety Audit. In particular they need to have undertaken basic training in collision investigation or road safety engineering.

Indicative Cost

Minimal cost other than personnel once foundational work to establish an electronic crash database is complete.

Common Issues and Solutions

Issues/crash themes are identified but there is no budget to treat them:

  • The cost of some treatments can be very small; some treatments can be combined into routine maintenance programmes at little or no extra cost
  • Undertaking Economic Appraisal or Cost Effectiveness analyses can help to make the business case for investment

Incomplete records or inaccurate records reduces reliability of analysis

  • Introduce mobile crash collection devices that allow checking for completeness as data are entered and cross checking for consistency of information
  • Introduce crash data systems that check for completeness and cross check for consistency of information
  • Training for police

Reliability of crash severities

  • Cross check against health/vital register data

Poor access to data

  • Data sharing protocols
  • Web-based database system

6.4 Road Safety Assessment

Fact Sheet: Road Safety Assessment

Description

Road Safety Assessments are undertaken on existing roads, normally in response to a known safety issue on the network.  For most road authorities it will not be possible to undertake in-depth Road Safety Assessments across the whole network, and so they will normally be triggered in response to known issues identified through:

  • Crash data analyses (e.g. blackspot analysis, route/corridor analysis, area analysis)
  • Local community or police intelligence about the location of crashes
  • Road Safety Inspections (e.g. routine scheduled inspections may help to identify sections that require more detailed examination

Road Safety Assessment is different from Road Safety Audit in that Road Safety Assessment is carried out on existing roads and does not require the same level of independence from the design team. 

Road Safety Assessment is the review of an existing road (site, section or route) by experts to identify safety problems that may affect any users of the road. 

Like Road Safety Audit, a Road Safety Assessment is not a check against design standards.  There is a common misconception that a design that fully meets the relevant design standards will have no road safety problems.

During a Road Safety Assessment, the Assessment Team seek to identify any aspects of the scheme that could either contribute to crashes or increase the severity of a crash should one occur. After identifying and explaining the problem, Assessors should make recommendations on how to remove, or reduce, the risk posed by the identified road safety problem.  They may also be responsible for developing a treatment plan to address the issues identified.

If the Road Safety Assessment Team is responsible for the development of a Treatment Plan they will normally need to prioritise measures based on Economic Appraisal or Cost Effectiveness.

Ideally Road Safety Assessments will be carried out by personnel trained in Safe System working.

Links and Guidance References

AfDB has developed an Existing Roads – Proactive Approaches Manual that contains information on conducting Road Safety Assessment of Existing Roads, which can be found at: www.afdb.org/en/documents/document/road-safety-manuals-for-africa-existing-roads-proactive-approaches-51935/

If the Road Safety Assessment Team are required to develop a prioritised Treatment Plan the types of treatments and their effectiveness can be found in

When to Apply and on What Road Types

Road Safety Assessments can be applied on all existing roads; however it may be necessary to prioritise application of this method for high priority road sections only.  High priority roads may be identified through crash data analysis (see route/corridor studies), through police or community intelligence or through road safety inspections.

Data and Software Requirements

Ideally, Road Safety Assessments should be undertaken on sites or sections where there is known to be an issue.  In that case, crash data analyses can be used to inform and direct the site assessment and the development of a relevant treatment programme.

Personnel Requirements

The Assessment Team is made up of at least two road safety specialists – an Assessment Team Leader and an Assessment Team Member.  The Assessment Team can be augmented by specialists relevant for the type of Assessment being undertaken.  For example a specialist in Pedestrian Safety may be required if there is a concentration of pedestrian crashes. 

As with Road Safety Audit, Assessments are only as good as the Assessors themselves.  Therefore it is necessary to ensure that personnel have the necessary skills and experience and it is good practice for there to be clear requirements regarding the experience and qualifications of Road Safety Assessors:

  • Assessors are required to attend an initial training course in Road Safety Audit/Assessment
  • To qualify for the course, candidates need to be experienced in not only Audit/Assessment but also in the investigation of road traffic crashes and road safety engineering measures (normally 5-10 years of experience is required)
  • Assessors are required to complete Continued Professional Development in the fields of Road Safety Audit/Assessment, Crash Investigation or Road Safety Engineering
  • Assessors are experienced on the type of scheme that they auditing

Accreditation of Assessors is therefore an important topic.  Ideally Assessors need to have formal qualifications and their skills need to be kept up to date through CPD.  This can be done through membership of a learned society or through universities.  In the UK the Society of Road Safety Auditors (SoRSA) has been formed as part of the Chartered Institution of Highways and Transportation. 

Indicative Cost

The cost of undertaking Road Safety Assessments is relatively low and many studies have shown that similar activities are both effective and cost beneficial, achieving significant savings in crash numbers at relatively low cost. A study by Austroads (Macaulay and McInerney, 2002) found that for existing road assessments, recommendations had a benefit to cost ratio of 2.4:1 to 84:1. 

Common Issues and Solutions

Road Safety Assessment uptake is minimal:

  • Introduce a policy that requires Road Safety Assessments to be undertaken for the highest risk 10% of the road network
  • Develop a national Road Safety Assessment manual

Insufficient personnel in my country:

  • Ensure undergraduate civil engineers receive a grounding in RSA/Road Safety Assessment at university
  • Develop nationally recognised courses in RSA/ Road Safety Assessment
  • Use international experts to teach RSA/ Road Safety Assessment courses, mentor Auditors/Assessors and complete quality checks
  • Introduce CPD requirements

Quality issues:

  • Ensure crashes related to design elements are understood through thorough data analysis
  • Ensure that there are clear requirements for the level of experience required of Auditors/Assessors in the national policy
  • Use international auditors/assessors to mentor new Auditors/Assessors and complete quality checks
  • Introduce an accreditation/society membership to ensure that Auditors/Assessors continue their professional development

Recommendations are not implemented:

  • Ensure there is budgetary provision for road safety improvements
  • Provide training to design engineers on road safety engineering

[1]Elvik, R., Vaa., T. Hoye, A., and Sorensen, M. (2009). The Handbook of Road Safety Measures (2nd Edition). Bingley: Emerald Group Publishing.

6.5 Road Safety Audit

Fact Sheet: Road Safety Audit (New Roads)

Description

A Road Safety Audit (RSA) is an independent review of a highway scheme by road safety experts to identify potential road safety problems that may affect any users of the highway. RSAs are intended to identify road safety concerns early in the life of a project to make sure that any problems are identified and addressed both before the works are actually implemented and after construction.  An RSA is not a check against design standards, a technical audit or a redesign exercise. There is a common misconception that a design that fully meets the relevant design standards will have no road safety problems.

During an RSA, the auditors seek to identify any aspects of the scheme that could either contribute to crashes or increase the severity of a crash should one occur. After identifying and explaining the problem, auditors should make recommendations on how to remove, or reduce, the risk posed by the identified road safety problem.  However, the designer and client have the final responsibility on how these recommendations should be implemented.

RSAs should ideally be undertaken at every stage of the design process and take into account the safety of all road users.  At a very minimum, all new roads and schemes should be subjected to RSA at one stage before construction and one stage after construction.

 

The stages of Road Safety Audit are identified, as follows:

Feasibility stage RSA takes place on completion of scheme feasibility to check for safety issues at this very early stage.

Preliminary stage RSA takes place once the preliminary design has been completed.  This usually deals with the general alignment, junction control, and road user issues. It is the last opportunity to identify additional land-take or easements that may be required.

Detailed design stage RSA takes place on completion of detailed design and looks at the detailed design of the scheme, including road geometry, position of signs, road markings, junction layout, and lighting provision.  Site visits should be made at this stage to help visualize arrangements.

Construction stage RSA takes place during construction to check the safety of the road during construction (if open for use).  The construction RSA focuses on advance warning and clarity of the route for drivers, clear guidance through use of signs and other devices, provision of unobstructed routes for pedestrians and cyclists, speed control, clear and efficient traffic control, protection of workers and safe access/egress for construction vehicles.  As a number of different temporary traffic layouts may be needed during the construction process it is important that each change in planned layout is subjected to a separate RSA.

Pre-opening stage RSA takes place on completion of the works, before opening to road users. The audit team should drive, cycle and walk along the scheme to evaluate the impact of changes for all road users and identify any potential road safety hazards. Night-time visits are also made at this stage.

Post-opening stage RSA takes place a few days after the road opens. This will show how the road is actually being used, and, if there are any problems, they will most likely be apparent already. It may be possible to make minor changes before the contractor fully demobilises. A Post-Opening Audit is conducted primarily around a detailed site visit of all elements and the interaction of how vehicles and non-motorised users are coping with the revised/improved facilities. Any unexpected conflicts or behaviors need to be noted. It can be helpful to undertake informal conflict studies.

Operational stage RSAs take place 12 and 36 months after the scheme has opened.  They involve investigating the safety effects of implemented schemes, and suggesting any appropriate remedial measures. Day-time and night-time site visits are made during these audits and they include analysis of crash data.

Specific RSAs can be completed on roadwork traffic schemes and for land use developments.  It is also good practice, in locations with high pedestrian or pedal cyclist use, to complete specific Non-Motorized User (NMU) audits. 

RSAs can also be conducted on existing roads to identify any prevailing road safety problems.  These are called Road Safety Assessments.

Links and Guidance References

It is important to ground RSA in legislation and to have formal national policies and manuals in order to ensure that it is undertaken on every new road scheme in a consistent manner.

The UK, Australia and New Zealand have comprehensive Road Safety Audit procedures detailed in their highway design manuals. In the UK this is standard HD19/03 and a new standard is currently in Interim Advice Note format, for Austroads it is AGRS06-09

The Danish Road Association has two publications on audits: road safety audit manual and road safety audit checklist

The Asian Development Bank has a document published on road safety audits that can be used as a checklist. 

PIARC has developed a Road Safety Audit guideline which can be found at: www.piarc.org/en

AfDB has developed an RSA manual for use across Africa, which can be found at: www.afdb.org/en/documents/document/road-safety-manuals-for-africa-new-roads-and-schemes-road-safety-audit-51937/

When to Apply and on What Road Types

RSA can be applied on all new roads and schemes. It may be necessary, as the process is introduced, to focus on higher traffic volume roads.  However with time, ideally all new roads and schemes, no matter how small, should be subjected to RSA.

Data and Software Requirements

Crash data are required for post opening stage monitoring audits that are completed after the road has been opened to traffic.  Where a new scheme is upgrading or replacing an existing road, crash data should be supplied for all stages of audit to identify issues on the existing road that need to be considered during the new design. There are no specific software requirements, although access to current design standards and works specifications is necessary.

Personnel Requirements

The Audit Team is made up of at least two road safety specialists – an Audit Team Leader and an Audit Team Member.  The Audit Team can be augmented by specialists relevant for the type of audit being undertaken.  For example, a town planner may be appropriate for a feasibility stage audit, structures, ITS and environmental specialists may be required for other RSAs.  At pre-opening stage the transport/traffic police and the organization responsible for maintaining the highway are also invited to accompany the audit team on the site visit. 

RSAs are only as good as the Auditors themselves.  Therefore it is necessary to ensure that Auditors have the necessary skills and experience and it is good practice for there to be clear requirements regarding the experience and qualifications of Road Safety Auditors:

  • Auditors are required to attend an initial training course in Road Safety Audit
  • To qualify for the course, candidates need to be experienced in not only RSA but also in the investigation of road traffic crashes and road safety engineering measures (normally 5-10 years of experience is required)
  • Auditors are required to complete Continued Professional Development in the fields of Road Safety Audit, Crash Investigation or Road Safety Engineering
  • Auditors are experienced on the type of scheme that they auditing

Accreditation of Auditors is therefore an important topic.  Ideally Auditors need to have formal qualifications and their skills need to be kept up to date through CPD.  This can be done through membership of a learned society or through universities.  In the UK the Society of Road Safety Auditors (SoRSA) has been formed as part of the Chartered Institution of Highways and Transportation.  This society has a membership requirement based on the experience requirements stated in the UK standard and awards Certificates of Competence in accordance with the RSA requirements contained in Directive 2008/96/EC of the European Parliament and of the Council of 19 November 2008 on road infrastructure safety management.

Accrediting bodies include:

Indicative Cost

The cost of undertaking RSAs is relatively low (often less than 4% of the scheme cost) and many studies have shown that RSAs are both effective and cost beneficial, achieving significant savings in crash numbers at relatively low cost and with minimal project delay.

The UK Highways Agency (Wells 1999, as cited in OECD, 2008) compared the cost of implementing recommendations made by a design stage audit to making changes after the project was constructed, they found an average saving per scheme of £11,373.  A study by Austroads (Macaulay and McInerney, 2002) found that for nine design stage audits, recommendations had a benefit to cost ratio of 3:1 to 242:1.  For existing road assessments, recommendations had a benefit to cost ratio of 2.4:1 to 84:1. 

Common Issues and Solutions

RSA uptake is minimal:

  • Introduce legislation making RSA mandatory for all road schemes
  • Develop a national RSA policy and manual
  • Introduce contractual gateways to stop progression to the next stage until a RSA has been undertaken and recommendations incorporated

Insufficient RSA personnel in my country:

  • Ensure undergraduate civil engineers receive a grounding in RSA at university
  • Develop nationally recognised courses in RSA
  • Use international auditors to teach RSA courses, mentor Auditors and complete quality checks
  • Introduce CPD requirements
  • Create demand for RSAs through introduction of a national policy and manual - recognise Road Safety Engineering/Audit as a profession

Quality issues:

  • Ensure crashes related to design elements are understood through thorough data analysis
  • Ensure that there are clear requirements for the level of experience required of Auditors in the national policy
  • Use international auditors to mentor new Auditors and complete quality checks
  • Introduce an accreditation/society membership to ensure that Auditors continue their professional development

Recommendations are not implemented:

  • Ensure there is budgetary provision for road safety improvements
  • Provide training to design engineers on road safety engineering

6.6 Road Safety Impact Assessment

Fact Sheet:  Road Safety Impact Assessments (of any planning)

Description

Most road safety problems, especially those that are difficult to treat retrospectively, are created at the planning stage, when insufficient consideration is given to the impact of a proposed development on road safety. RSIA is an important focus of the Global Plan for the Decade of Action for Road Safety 2011-2020, with a key objective of Pillar 2 being "Promoting the needs of all road users as part of sustainable urban planning, transport demand management and land-use management by including safety impact assessment as part of all planning and development decisions."

In some countries Road Safety Impact Assessments (RSIAs) are embedded, along with Environmental Impact Assessments (EIA), within Transport Assessments (TAs) or Traffic Impact Assessments (TIAs).

The European Parliament published Directive 2008/96/EC, which introduces a comprehensive system of road infrastructure safety management; this includes a requirement for RSIAs. The EU Directive defines RSIA as: "A strategic comparative analysis of the impact of a new road or a substantial modification to the existing network on the safety performance of the road network; carried out at the initial planning stage before the infrastructure project is approved. It shall further provide all relevant information necessary for a cost-benefit analysis of the different options assessed."

Scenario methods can be used to carry out a RSIA, with the following stages forming part of the RSIA:

  • Problem definition
  • Description of the current situation and the "do nothing" scenario
  • Formulation of road safety objectives
  • Analysis of impacts of the proposed alternatives
  • Comparison of the alternatives (including cost-benefit analysis)
  • Description of the best solution

Links and Guidance References

 

When to Apply and on What Road Types

Ideally RSIA would be applied to all new roads and schemes, however as the process is being introduced it may be necessary to focus efforts on major schemes on high volume roads.

Data and Software Requirements

Road crash data (where possible expected risk rates by road type).  Accepted crash costing figures for different severity casualties or crashes are required for RSIA.  Software for calculation of cost benefits. An evidence base on the expected impact of different road design options.

Personnel Requirements

RSIAs are quite difficult to complete.  Personnel must have a good grasp of both economics and road safety engineering.  In terms of economics it is necessary for personnel to understand crash costings and how they can be used and how to complete an economic evaluation of costs and benefits.  A good understanding of the impacts of different options on crash numbers is also required, using sources such as Elvik, Vaa, Hoye and Sorensoen (2009). The Handbook of Road Safety Measures.

Indicative Cost

 The cost of undertaking RSIAs is low as it is largely a desk based study.

Common Issues and Solutions

RSIA uptake is minimal:

  • Introduce legislation making RSIA mandatory for all large projects that will have an influence on road traffic
  • Develop a national RSIA policy and manual

Insufficient RSIA expertise in my country:

  • Ensure undergraduate civil engineers receive a grounding in RSIA at university
  • Develop nationally recognised courses in RSIA
  • Seek international expertise to assist in the development of RSIAs, ensuring opportunity for knowledge transfer to local staff

6.7 Road Safety Inspection

Fact Sheet: Road Safety Inspection

Description

RSIs aim to identify safety deficits and potential hazards proactively across the network so that any proposed remedial treatment may be implemented before crashes happen. Deficits may include missing, damaged or worn equipment, signing or delineation, along with more fundamental road safety issues such as the presence of hazardous obstacles at the road side, inappropriate speed limits or lack of median treatment.

To complete an RSI, a trained team collects information about the character and features of the road network and video the route. The information recorded by the team is then passed to an experienced road safety engineer to assess whether systematic improvements are appropriate and/or whether more detailed investigation is necessary through a Road Safety Assessment (see Existing Roads: Reactive Approaches manual).

Because the survey-based assessment is systematic, this type of RSI does not require the same level of specialist expertise as Road Safety Audit or Assessment.

Ideally RSIs will be undertaken every 3-5 years according to a schedule. 

Other tools exist that review existing roads for particular road user groups, for example, Pedestrian Environment Review System (PERS) assesses provision of facilities for pedestrians, and Cycle Environment Review System (CERS) does the same for cyclists.

Other tools like PERS/CERS based on similar processes.

Links and Guidance References

AfDB manuals – Existing Roads – Proactive Approaches contains guidance on undertaking RSIs can be found at: www.afdb.org/en/documents/document/road-safety-manuals-for-africa-existing-roads-proactive-approaches-51935/

When to Apply and on What Road Types

RSI can be applied on all existing roads.  However as the process is introduced it may be necessary to focus limited resource on higher volume roads.

Ideally RSIs will be undertaken every 3-5 years according to a schedule. 

Data and Software Requirements

No data are required for RSIs, though it can be helpful to combine the results of RSIs with blackspot or route/corridor analyses to determine whether crash history relates to any of the deficits identified.

Equipment required includes:

  • A vehicle (with appropriate high visibility markings)
  • Video camera (ideally GPS linked system)
  • GPS (can be achieved using a satellite navigation system or smart phone)
  • Inspection forms
  • Personal Protective Equipment (e.g. high visibility clothing and protective footwear)

Personnel Requirements

RSI Teams require two inspectors (RSI can be a repetitive and monotonous task and so two Inspectors ensures greater accuracy), they may take it in turns to drive or there may be a separate driver.

Ideally Inspectors should have at least 2 years– experience working within the highway industry (roles could include traffic engineer, safety engineer, maintenance engineer or transport planner). It is not necessary for the Inspection Team Leader or Team Member to have differing levels of training or experience.

When RSI is being introduced to a country then the Inspection Team would initially be accompanied by an experienced Road Safety Assessor to ensure that the RSI Team is equipped and competent to undertake this task.

Indicative Cost

Cost of local personnel to undertake regular inspections of network will depend on network length.  Cost/km will be very low.

Common Issues and Solutions

RSI uptake is minimal:

  • Introduce legislation making RSI mandatory
  • Develop a national RSI procedure, policy or manual

Insufficient RSI personnel in my country:

  • Develop a training course for RSI – this should be around a 5 day training course

Quality issues:

  • Undertake with the oversight of a trained Road Safety Auditor/Assessor
  • Develop a clear procedure and forms

Recommendations are not implemented:

  • Ensure there is budgetary provision for road safety improvements
  • Provide training to design engineers on road safety engineering

6.8 Route/Corridor Analysis and Treatment

Fact Sheet: Route/Corridor Analysis and Treatment

Description

In route/corridor analysis, the road network is split into sections and the crash history analysed by road section.  Ideally, the sections are categorised by road type (single or divided carriageway and high, medium or low traffic flow) and the crash density (number of crashes per km) is compared to the average crash density for that road type.  The potential for crash savings is calculated by estimating the number of crashes that would be saved if that road section were raised to the average standard for that road type.

Crashes at the high risk section are analysed to identify common patterns that may relate to an underlying safety problem.  These analyses can be helped through the use of cross tabulations, stick analyses and crash diagrams.

High priority sections are then investigated through a site visit where road defects and corresponding treatments can be determined.  Often treatments are very inexpensive. 

Links and Guidance References

AfDB Existing Roads – Reactive Approaches Manual can be found at: www.afdb.org/en/documents/document/road-safety-manuals-for-africa-existing-roads-reactive-approaches-51936/

 

When to Apply and on What Road Types

Route/corridor analyses can be undertaken annually on all existing roads.  

It may not be possible to cover all road types as the process is being introduced due to resource limitations.  Therefore if necessary efforts can be focused on higher volume roads.

Data and Software Requirements

Location information for crashes is required in order to assign crashes to a predefined section. 

Some crash database software packages contain functionality to support such analyses.

Personnel Requirements

Data analyses can be undertaken by a member of staff with an engineering, mathematics or statistics background.  Though they would have the pre-requisite skills to undertake such analyses in a systematic manner, formal training is recommended.  

Once the initial analyses have been carried out, the site visits and assessment of potential remedial measures should be undertaken by experienced road safety engineers with similar qualifications to those described for Road Safety Audit. In particular they need to have undertaken basic training in collision investigation or road safety engineering.

Indicative Cost

Once an electronic crash database has been established, there are minimal costs associated with undertaking route/corridor analyses. 

Common Issues and Solutions

Lack of precise information on crash locations:

  • Introduce GPS devices for recording coordinates at the scene
  • Tablet/mobile devices to allow recording of accurate crash locations

High risk sections are identified but there is no budget to treat them:

  • The cost of some treatments can be very small; some treatments can be combined into routine maintenance programmes at little or no extra cost
  • Undertaking Economic Appraisal or Cost Effectiveness analyses can help to make the business case for investment

Incomplete records or inaccurate records reduces reliability of analysis:

  • Introduce mobile crash collection devices that allow checking for completeness as data are entered and cross checking for consistency of information
  • Introduce crash data systems that check for completeness and cross check for consistency of information
  • Training for police

Reliability of crash severities:

  • Cross check against health/vital register data

Poor access to data:

  • Data sharing protocols
  • Web-based database system

6.9 Star Rating (iRAP) – Existing Roads

Fact Sheet: Star Rating (iRAP) – Existing Roads

Description

iRAP Star Ratings are an independent and objective measure of the level of safety which is "built-in" to the road for vehicle occupants, motorcyclists, bicyclists and pedestrians. Star Ratings involve an inspection of road infrastructure attributes that are known to have an impact on the likelihood of a crash and its severity.

iRAP Star Ratings utilise specially equipped vehicles, software and trained personnel, iRAP inspections involve detailed road surveys and data collection, focusing on more than 50 different road attributes that are known to influence the likelihood of a crash and its severity. Importantly, Star Ratings can be completed without reference to detailed crash data, which is often unavailable in low-income and middle-income countries.

The safest roads (4- and 5-star) have road safety attributes that are appropriate for the prevailing traffic speeds. Road infrastructure attributes on a safe road might include separation of opposing traffic by a wide median or barrier, good line-marking and intersection design, wide lanes and sealed (paved) shoulders, roadsides free of unprotected hazards such as poles, and good provision for bicyclists and pedestrians such as footpaths, bicycle lanes and pedestrian crossings.

The least safe roads (1- and 2-star) do not have road safety attributes that are appropriate for the prevailing traffic speeds. These are often single-carriageway roads with frequent curves and intersections, narrow lanes, unsealed shoulders, poor line markings, hidden intersections and unprotected roadside hazards such as trees, poles and steep embankments close to the side of the road. They also do not adequately accommodate bicyclists and pedestrians with the use of footpaths, bicycle paths and crossings.

iRAP Safer Roads Investment Plans (SRIP) are a prioritised list of countermeasures that can cost-effectively save lives, improve Star Ratings and reduce infrastructure-related risk. The plans are based on an economic analysis of a range of countermeasures, which is undertaken by comparing the cost of implementing the countermeasure with the reduction in crash costs that would result from its implementation. The plans contain extensive planning and engineering information such as road attribute records, countermeasure proposals and economic assessments for 100 metre segments of a road network.

Links and Guidance References

iRAP provide detailed information about Star Rating and Investment Plans on their website: www.irap.org

iRAP technical specifications, guides and manuals, which can be used in procurement and management of iRAP-specification activities can be found at: www.irap.org/en/about-irap-3/specifications

The "iRAP Methodology" fact sheets which describe the Star Rating and Safer Roads Investment Plan methodologies, and the "iRAP Road Attribute Risk Factors" fact sheets which describe the risk factors used in the models, can be found at: www.irap.org/en/about-irap-3/methodology

A selection of reports that contain iRAP assessment results, including Star Ratings and Safer Roads Investment Plans, can be found at: www.irap.org/en/about-irap-3/assessment-reports

Research and technical papers related to iRAP Star Ratings and Investment Plans can be found at: www.irap.org/en/about-irap-3/research-and-technical-papers

The business case for safer roads is available for every country worldwide at: www.irap.org/en/about-irap-2/a-business-case-for-safer-roads

When to Apply and on What Road Types

iRAP assessments can be undertaken on urban or rural roads; high-speed or low-speed roads; high volume or low volume roads and sealed or unsealed roads. 

iRAP Star Ratings and Safer Roads Investment Plans can be used as part of a systematic, proactive approach to road infrastructure risk assessment and renewal based on research about where severe crashes are likely to occur and how they can be prevented.  iRAP assessments can be undertaken on existing roads and as part of design star ratings.

iRAP assessments can be used from full road network, down to individual pilot corridor projects.  In general iRAP recommend the initial targeting of the highest volume 10% of roads where typically more than half of all road deaths occur.

Data and Software Requirements

An iRAP Star Rating assessment requires video or visual inspection data (e.g. dedicated survey vehicle; satellite data; video data; site inspections) and the coding of more than 50 different road attributes. Supporting data for the network is also required, that includes operating speed data, volume data and network level crash data estimates.

The coding of the road segments is required in .csv format for uploading to the iRAP analysis software.  Coding software is provided by accredited iRAP suppliers that ensure the required quality and accuracy of any coding activities can be achieved. 

iRAP Star Ratings and Investment Plans are calculated by ViDA, iRAP's online road safety software platform. Users of ViDA are able to upload road inspection data to produce detailed road condition reports, Star Ratings and Safer Roads Investment Plans.

Personnel Requirements

An  iRAP Star Rating assessment is typically delivered in the following five phases:

Project Leadership – to ensure roads are upgraded and lives saved it is recommended that any iRAP project includes a steering committee involving key stakeholders (e.g. road funders; policy experts; NGO partners; design teams and maintenance providers in addition to Police and Health partners).  All iRAP assessments must meet strict quality requirements and experienced project management teams should oversee the project.

Road survey – this is the collection of road survey data (image/video in combination with detailed location data). Road Surveys require an iRAP accredited inspection system, which would typically be operated by two or three staff.  The safe operation of the survey is an important priority given the high risk environment in which the surveys are undertaken.

Road coding – this is the coding (collection) of road features from the road survey data. Some road features can be collected using machine data (e.g. geometry); existing asset data held by the road agency or coded from the video images.  Dedicated, well trained and accredited teams of coders are now available worldwide.

Analysis and reporting – this is the process of collecting the supporting data, establishing a project in ViDA and uploading the road coding data to generate the Star Ratings and Investment Plans. This typically requires between one and three senior technicians or road engineers.

Implementation support – this is the process of communicating the results to policy makers and road engineers, supporting them in the implementation of the recommendations This typically requires between one and three senior technicians or road engineers.

iRAP maintain a network of road safety professionals and companies capable of competitively bidding to provide high-quality iRAP assessments is growing.

iRAP lists companies that have experience in delivering iRAP projects and/or are accredited to undertake iRAP-specification surveys. It can be found at: www.irap.org/en/resources/accredited-suppliers

Indicative Cost

The cost to carry out an iRAP Star Rating assessment and Investment Plan is dependent on the length of road, type of road (e.g. proportion of urban road) included.

An iRAP Star Rating and Investment Plan of around 3,000 carriageway kilometres, including training, can cost in the order of $50 to $150 per carriageway kilometre.

To encourage competitive costs and suitably qualified teams each of the phases of an iRAP Star Rating and Investment Plan assessments are able to be open tendered.

Common Issues and Solutions

iRAP surveys use a drive-through survey, coded retrospectively, to collect its core data.  All countermeasure recommendations must be –sense-checked– at various stages and by local engineers with a site visit.  Coding is a demanding task and teams must be selected carefully, well-managed and given adequate rest breaks.  Adequate time and funding must be allocated in follow-up implementation support.  Ideally a budget for road upgrades should be secured prior to the commencement of the iRAP assessment.  Roads must be upgraded for lives to be saved!

6.10 Star Rating (iRAP)–New Roads and Schemes

Fact Sheet: Star Rating (iRAP) – New Roads and Schemes

Description

Apart from assessing existing roads, Star Ratings are being used to ensure that safety is built-in to designs for upgrades and new roads prior to construction. The Star Rating of Designs provides an objective measure of the safety of the design and can be used to specify target performance levels (e.g. minimum 3-star or 4-star for all road users).  The Star Rating of Designs can work in parallel with local design standards as designers apply problem solving skills to reach the target start rating.  iRAP Star Rating of new roads and schemes utilise design plans and trained personnel, to determine more than 50 different road attributes that are known to influence the likelihood of a crash and its severity. Importantly, Star Ratings can be completed without reference to detailed crash data, which is often unavailable in low-income and middle-income countries or for new road alignments and designs.

For governments and development banks, the process opens the opportunity to set performance-based targets for vehicle occupants, motorcyclists, pedestrians and bicyclists that not only improve safety but create a high level of transparency and accountability.

The safest roads (4- and 5-star) have road safety attributes that are appropriate for the prevailing traffic speeds. Road infrastructure attributes on a safe road might include separation of opposing traffic by a wide median or barrier, good line-marking and intersection design, wide lanes and sealed (paved) shoulders, roadsides free of unprotected hazards such as poles, and good provision for bicyclists and pedestrians such as footpaths, bicycle lanes and pedestrian crossings.

The least safe roads (1- and 2-star) do not have road safety attributes that are appropriate for the prevailing traffic speeds. These are often single-carriageway roads with frequent curves and intersections, narrow lanes, unsealed shoulders, poor line markings, hidden intersections and unprotected roadside hazards such as trees, poles and steep embankments close to the side of the road. They also do not adequately accommodate for bicyclists and pedestrians with the use of footpaths, bicycle paths and crossings.

Links and Guidance References

iRAP provides detailed information about Star Rating and Investment Plans on their website www.irap.org

See (www.irap.org/en/about-irap-3/research-and-technical-papers) and (www.irap.org/en/about-irap-37performance-indicators-roads-in-india) as examples of this work.

iRAP technical specifications, guides and manuals, which can be used in procurement and management of iRAP-specification activities can be found at:   www.irap.org/en/about-irap-3/specifications

The 'iRAP Methodology' fact sheets which describe the  Star Rating and Safer Roads Investment Plan methodologies, and the 'iRAP Road Attribute Risk Factors' fact sheets which describe the risk factors used in the models, can be found at: www.irap.org/en/about-irap-3/methodology

A selection of reports that contain iRAP assessment results, including Star Ratings and Safer Roads Investment Plans, can be found at: www.irap.org/en/about-irap-3/assessment-reports

Research and technical papers related to iRAP Star Ratings and Investment Plans can be found at: www.irap.org/en/about-irap-3/research-and-technical-papers

When to Apply and on What Road Types

iRAP Design Star Ratings for new and existing roads can be completed on any level of road, however, it is suggested that they should initially focus on the primary and secondary tier road networks.

iRAP Design Star Ratings for new and existing roads can be applied at different stages through the design phase.  This can help inform and guide the design decisions relevant to the phase of the project.

Data and Software Requirements

iRAP Star Ratings of new roads an schemes are typically completed by manipulating data in Microsoft excel. Following this the Star Ratings are calculated by ViDA, iRAP's online road safety software platform. Users of ViDA are able to upload road inspection data to produce detailed road condition reports, Star Ratings and Safer Roads Investment Plans. 

Personnel Requirements

An iRAP Star Rating assessment of a corridor project will typically involve a team of between two and six, made up of road engineers (and senior technicians).

Indicative Cost

The cost to carry out an iRAP Star Rating assessment and Investment Plan is dependent on the length of road, the phase in the design process, type of road (e.g. proportion of urban road) included.  10-15km per person per day may be possible for a skilled assessor, dependent upon the complexity of the road.

Common Issues and Solutions

Many road designs do not include detailed information on the condition of the roadsides that may impact the severity of a run-off road crash.  In this case design drawings may need to be supplemented with site inspections, aerial or satellite photography or other sources of information.

All countermeasure recommendations must be –sense-checked– at various stages and by local engineers with a site visit.  Coding is a demanding task and teams must be selected carefully, well-managed and given adequate rest breaks.  Adequate time and funding must be allocated in follow-up implementation support.

6.11 Work Zone Safety Manuals

Fact Sheet: Work Zone Safety Manuals

Description

Road safety at work zones/road works is often extremely poor.  Introducing a work zone safety manual (and offering training to contractors in its implementation) can have a significant impact on the quality of work zones.

A work zone safety manual provides:

  • A clear outline of roles and responsibilities for work zone safety
  • A clear outline of the processes for the planning, review and approval of work zones
  • Guidance on the setting out and clearance of temporary traffic management
  • An overview of the types of works and how they need to be dealt with
  • An overview of the components of work zones and how they are required to ensure the safety of workers and the public
  • Guidance on the risk assessment process
  • Information on the traffic control devices for use (e.g. signs, delineation devices etc.)
  • Typical layouts that can be adapted for use in most situations, these include:
    • The components and safety buffers that need to be in place to protect road workers
    • The signing and delineation necessary to ensure the public have clarity on the desired path through the work zone and the required speed

The development of a Work Zone manual is only the beginning for improving the safety of road works/work zones.  As well as a manual, it is necessary to create a requirement for its application, training for contractors and a quality/inspection regime to ensure it is properly implemented.

Links and Guidance References

The UK–s Chapter 8 of the Design Manual for Roads and Bridges is available here: http://www.standardsforhighways.co.uk/ha/standards/dmrb/

When to Apply and on What Road Types

 The implementation of a work zone manual can be applied to all road types.

Data and Software Requirements

No data are required for the introduction of safe work zone practices.  It is advisable to collect and analyse data on crashes and incidents occurring at road works to determine what aspects of the works may have contributed to a crash or incident and to ensure safer policies or layouts can be introduced in the future.

Personnel Requirements

Various stakeholders are required for the implementation of a work zone manual.  They include:

  • The Work Zone regulatory authority (the designated authority who owns the requirement and manual)
  • The road authority (this may be the same as the regulatory authority)
  • The lead client (this could be the road authority or a municipality)
  • Police and emergency responders
  • The scheme designer
  • The scheme contractor – site safety supervisor/lead, temporary traffic management operatives, site operatives

All of the stakeholders will have staff that require training in order to achieve compliance with a sufficiently detailed manual.

Indicative Cost

Costs of developing a work zone manual need not be prohibitively high.  Many countries make their work zone manual available and so the principles can be adopted quite easily.

Implementing well-designed work zones will often pay for themselves, through reduced damage to equipment and lowering the potential for a road worker to be killed or seriously injured.

In introducing a work zone safety manual it can be challenging to ensure full compliance and so it is necessary to plan for extensive training for the stakeholders listed above and for an inspection regime.

Common Issues and Solutions

No work zone manual/policy in place:

  • Develop a manual based on good international practice (e.g. UK, Australia)

Lack of qualified personnel:

  • Introduce training courses as the manual is introduced

Lack of budget:

  • Ensure that the benefits of good work zone safety practice are well-understood and ensure sufficient budget available for the proper inclusion of good practice in construction projects (this is likely to be a very small percentage of overall scheme costs)

Poor compliance with the manual:

  • Ensure that adherence to the manual/policy is clearly stated as a requirement in contracts for those undertaking work
  • Introduce penalties for non-compliance
  • Undertake regular inspections for compliance
  • Introduce effective training explaining why work zone safety is important and how to ensure compliance

 

7. The Importance of Evaluation and Economics

7.1 Economic Appraisal of Potential Solutions

It is very rare that there will be sufficient budget available to make all desirable safety improvements.  Therefore it is necessary to prioritise these according to their benefits and their costs.  A simple method for undertaking economic appraisal of potential solutions is provided in the AfDB Existing Roads – Reactive Approaches Manual (Section 5.5.1)

7.2 Monitoring and Evaluation of Treatments

It is essential that once treatments are installed the impact is measured and formal evaluation undertaken.  If not it will not be possible to build an evidence base of what does, and what does not, work.  A simple method for undertaking before and after studies is provided in the AfDB Existing Roads – Reactive Approaches Manual (Section 6 and referenced appendices).  It should be noted that this is deliberately a pragmatic and simple method rather than a full research methodology that would ideally utilise Empirical Bayes.