Road Safety Impact Assessment
TII Publication: PE-PMG-02001
Road Safety Impact Assessment
Road Safety Impact Assessment (RSIA) is described in the EU Directive on Road Infrastructure Safety Management (EU RISM) as a strategic assessment of the impact of different planning options for a new road, or for substantial modifications to an existing road, on the safety performance of the road network. RSIA is required for such projects on the national road network. RSIA is also recommended for similar schemes on local and regional roads. TII Publications describe the RSIA process under the standard TII PE-PMG-02001 Road Safety Impact Assessment.
TII PE-PMG-02001 Road Safety Impact Assessment standard can be viewed here on TII Publications.
RSIA is a separate process to Road Safety Audit (RSA). While RSA examines the safety aspects within a scheme, RSIA considers the safety impact of a scheme on the surrounding road network. RSIA and RSA both work to improve the safety performance of new roads and existing roads that require modifications.
Road Safety Impact Assessment Team
Unlike Road Safety Audit, RSIA is performed by the project design team. The RSIA team is a minimum of two people, one with road design experience and the other, with road safety auditing experience.
Road Safety Impact Assessment Process
The RSIA is carried out at the initial planning stage of a project and it is continually revised throughout the design stages until the scheme is approved.
The safety performance of the existing road network is assessed by the RSIA team. The team examines the current road network in terms of a number of factors, including collision history and traffic flows. This analysis allows the team to estimate the impact that the proposed infrastructure project will have on the safety performance of the current road network.
The RSIA team is presented with a number of planning options for a scheme. During RSIA, the team performs a comparative analysis of those planned options, which includes the existing situation at the site and a ‘do minimum’ alternative. This comparison is based on collision reduction and cost-benefit analysis.
In order to compare the proposed alternatives, the RSIA team assess the impact of each planning option on the existing road network in terms of collision performance. The evaluation of each alternative is based on a number of factors, some of which include:
- The scheme objectives
- Collision data
- Traffic surveys
A cost-benefit analysis is carried out as part of RSIA for each scheme option. This cost-benefit analysis calculates the various collision costs of the existing road network and the planned alternatives. The results of the cost-benefit analysis serve as another method for comparing alternative schemes.
The team use the results of RSIA to rank the proposals for the site in terms of their road safety implications. This ranking includes all of the planning options as well as the existing situation at the site.
Road Safety Impact Assessment Report
The RSIA team prepare a report that combines all the Road Safety Impact Assessments that have been completed throughout the design process. The report is submitted to the Design Project Manager who will consider the RSIA findings at the route selection stage. The final RSIA report is also submitted to the overseeing organisation (TII for national roads) as it will contribute to the determination of the project objectives. See Chapter 3 of TII PE-PMG-02001 Road Safety Impact Assessment for a list of elements that must be addressed in the RSIA report.