Deterioration Unsealed Roads

2 Gravel Earth (or Sand) * Unsealed Roads Classification * Engineered roads

3 Unsealed Roads

4 Unsealed Roads Deterioration

5 Roughness Material Loss Rutting Looseness Impassability Models of Distress HDM-4

6 Preservation Routine  Off carriageway  Grading  Spot regravelling Periodic  Regravelling Special  Emergencies  Winter maintenance Development Improvement s  Widening  Realignment Construction  Upgrading  New sections Unsealed Road Work Classification

7 Roughness:  Progression  Effect of mechanical compaction  Effect of grading  Average annual roughness  Steady state roughness Material Loss Unsealed Roads Models

8 Roughness Without Compaction

9 Grading

10 Effect of Grading on Roughness

11 Long term average roughness

12 Roughness: Effect of Grading Frequency and Traffic

13 Roughness: Effect of Terrain Type and Traffic

14 Roughness: Effect of Environment Type and Traffic

15 Roughness: Effect of Material Properties

16 Material loss Effect of Rainfall and Traffic

17 Material loss Effect of Rainfall and Terrain

18 Road Roughness of Unsealed Roads Roughness equations valid for engineered unsealed roads with good maintenance (good drainage). Therefore:  Higher rainfall yields lower roughness  Higher percent of trucks yields lower roughness  Earth roads (finer soils) have lower roughness than gravel roads, making difficult to evaluate regravelling works In practice, the condition of an unsealed road can be different from what is being predicted by the HDM models, specially related to the passability on the wet season

19 Road Roughness of Unsealed Roads HDM equations for deterioration of unsealed roads are valid for engineered roads with proper drainage There is a need to understand the HDM relationships and calibrate the equations if proper drainage is not available