Appraisal and cost-estimate assurance

Application

Project identification and selection guidance, compile and challenge appraisal, cost, and benefit evidence before selection, approval, and tender decisions; use sensitivity testing, optimism-bias adjustments, benchmarking, and reference class forecasting to identify unsupported assumptions, understated costs, overstated benefits, and weak evidence, and require revision or escalation before the project advances.

Resources

• Appraisal and cost-estimate evidence pack (assumptions register, sensitivity analysis, scenario analysis)

  Template

  HM Treasury, UK

  HM Treasury. (2026). The Green Book: UK government guidance on appraisal. Available from: https://www.gov.uk/government/publications/the-green-book-appraisal-and-evaluation-in-central-government

  Available from ↗ Download static copy ↓

• The Green Book – Guidance on Appraisal

  Guideline

  UK Government

  UK Government. (2026). The Green Book – Guidance on Appraisal. Available from: https://assets.publishing.service.gov.uk/media/698dbcd17da91680ad7f4308/The_Green_Book_2026.pdf

  Available from ↗ Download static copy ↓

• Infrastructure Business Case: International Guidance

  Guideline and Template

  Infrastructure and Projects Authority, UK

  Infrastructure and Projects Authority. (2026). Infrastructure business case: International guidance (2nd ed.). Available from: https://ukgreencitiesandinfrastructure.org/wp-content/uploads/2026/06/Infrastructure_Business_Case_International_Guidance.pdf

  Available from ↗ Download static copy ↓

• Optimism-bias uplifts and outside-view adjustments

  Guideline

  HM Treasury

  HM Treasury. (2013). Green Book supplementary guidance: Optimism bias. Available from: https://assets.publishing.service.gov.uk/media/5a74dae740f0b65f61322c72/Optimism_bias.pdf

  Available from ↗ Download static copy ↓

• Benchmarking and reference class forecasting approach

  Guideline

  Flyvbjerg, B

  Flyvbjerg, B. (2008). Curbing optimism bias and strategic misrepresentation in planning: Reference class forecasting in practice. Available from: https://www.researchgate.net/publication/233258056_Curbing_Optimism_Bias_and_Strategic_Misrepresentation_in_Planning_Reference_Class_Forecasting_in_Practice

  Available from ↗ Download static copy ↓

• Appraisal & cost, benefit and estimate evidence pack (BoE, ranges, optimism-bias, benchmarking)

  Template

  AACE International

  AACE International. (2021). Recommended Practice 34R-05: Basis of estimate. AACE International. Available from: https://web.aacei.org/docs/default-source/toc/toc_34r-05.pdf

  Available from ↗ Download static copy ↓

• Guide to the socioeconomic cost–benefit analysis of infrastructure investment projects

  Guidance

  Ministry of Economy, Brazil

  Brazil. Ministry of Economy. Special Secretariat for Productivity and Competitiveness. Secretariat for Infrastructure Development. (2023). Guia geral de análise socioeconômica de custo-benefício de projetos de investimento em infraestrutura (version 3.). Available from: https://www.ppi.gov.br/wp-content/uploads/2023/01/Guia-ACB.pdf

  Available from ↗ Download static copy ↓

• Guidance to support investment pipeline selection

  Guidance

  Instituto Brasileiro de Auditoria de Obras Públicas, Transparência Internacional Brasil, Instituto Socioambiental, Instituto de Energia e Meio Ambiente, GT Infraestrutura e Justiça Socioambiental

  Instituto Brasileiro de Auditoria de Obras Públicas, Transparência Internacional – Brasil, Instituto Socioambiental, Instituto de Energia e Meio Ambiente, GT Infraestrutura e Justiça Socioambiental. (2023). Critérios para análise e classificação de empreendimentos de infraestrutura propostos para inclusão no Plano Plurianual 2024–2027 e no Programa de Parcerias de Investimentos (PPI). Available from: https://energiaeambiente.org.br/wp-content/uploads/2023/06/notatecnica_infraestrutura2023.pdf

  Available from ↗ Download static copy ↓