1. Paving a Gravel Road Case Study
Christopher R. Bennett
Director - Data Collection Ltd.
The World Bank
Paving a Gravel Road Case Study

2. The Scenario
Without Project Case - Routine maintenance - Gradings every 180 days - Regravelling when gravel < 50 mm
With Project Case - Pave the road in and after paving - Routine maintenance - Pothole patching - Resealing when damaged area > 20 %
Gravel Road with 200 AADT

3. Road Deterioration and Timing of Works
Replace Gravel at 50 mm
Paving
Reseal at 20% damaged area

4. Alternatives and Standards
Maintenance Standard
Alternative 1 with 1 Standard
Maintenance Standard
Alternative 2 with 2 Standards
Improvement Standard

5. Comparison of Alternatives

6. Net Present Value (NPV)
Case without Generated Traffic
Paving a Gravel Road Case Study

7. Total Society Costs

8. Internal Rate of Return (IRR)
NPV
IRR
Paving a Gravel Road Case Study

9. Distribution of Net Benefits

10. Project Impact

11. Generated Traffic Benefits

12. Transport Demand Elasticity

13. Generated Traffic Benefits Example

14. Optimal Grading Frequency (Efficiency Frontier Graph)

15. Optimal Grading Frequency (Average Roughness Graph)

16. Optimal Paving Timing (Efficiency Frontier Graph)

17. Unpaved Network Maintenance Funding Second State Highway Management Project Brazil, 1994
No of Gradings per Year Average Roughness Net Present Value Economic Costs/Year/km ($) Financial Costs/Year/km ($) Total Financial Costs/Year (M$); 1,838km

18. Selection and Justification of Project Components Second State Highway Management Project Brazil, 1994
New length (km) Initial Traffic (ADT) Initial Roughness (IRI) ERR (%) NPV (M US$) Financial Project Cost (M US$) Financial project Cost/km (US$/km)
Total State ERR, Length, and Financial Project Cost

19. Accident Rates Number per 100 million vehicle-km
- South Africa: Economic Warrants for Surfacing Roads, 1989, SABITA and CSIR - Canada : The Economic Appraisal of Highway Investment “Guidebook”, 1992, Ministry of Transportation

20. Accident Rates
Number per 100 million vehicle-km

21. Accident Rates Assumptions
Different Proportion
Same Proportion

22. Accidents and NMT Benefits
Base With With Accidents Accidents & NMT
NPV
IRR 18.9% % 22.2% NMT => 10 Bicycles ($75 purchase cost) 5 Rickshaws ($130 purchase cost) 5 Animal Carts ($180 purchase cost)