1. HDM-4: The Road Deterioration and Maintenance Effects Study

2. The Project Team Mike Riley Louw Kannemeyer Tom Van Dam
Alex Visser/Gerrie Van Zyl
Gustav Rohde
Zulakmal bin Sufian
Peter Cenek

3. Limitations of HDM-III from the RDME viewpoint
HDM-III does not consider:
Rigid pavements
Many types of flexible pavements
Pavement texture and skid resistance
Freeze-thaw conditions

4. Other criticisms Heavily biased toward South American conditions
Empirically tied to specific
construction materials
environment
Ignores urban roads

5. Project Objectives Focus on areas not addressed in HDM-III
Little, if any, primary research
Consider available research and implement appropriate findings
Provide guidance on inputs and selection of calibration coefficients

6. Research Tasks 1010: Review of Experience
1020: Pavement Strength and FWD
1030: Rigid Pavement Models
1040: Extension of AC Models
1050: Maintenance Effects
1060: Texture Effects

7. Task 1010: Review of Experience
Status: Draft issued at end of 1994
Reports from 45 countries were reviewed
Summarises pavement relationships of HDM-III
Presents calibrations used in other studies
Found wide use of HDM-III models but not a lot of guidance on new models

8. Task 1020:Strength and FWD
In HDM-III, strength represented by SNC, modified Structural Number
Relationships provided between BB deflection and SNC for different materials
Widespread use of FWD has spurred the development of MSN-FWD relationships

9. Task 1020:Continued
FWD has potential to provide more data in cost-effective manner
Work by Gustav Rohde of South Africa has led to a proposed model of the following form:
SN = a0 SIP HP a1 a2

10. Task 1030: Modelling Rigid Pavement Deterioration
HDM-III did not include rigid pavements
There are sufficient countries that have them to warrant their inclusion
Team from Chile has undertaken this effort

11. Task 1040: Extend Flexible Pavement Models
Identify pavement types
Refine existing and develop new
Quantify default parameters
Effect of prior condition
Skid resistance modelling
Freeze/thaw conditions
Urban pavements

12. HDM-4 Pavement Types
Primary objective is to expand pavement
types to cover a broader range

13. Proposed Typical Characteristics

14. 1040-2: Pavement Models Rutting Ravelling Cracking Potholing Roughness
Others: edge deterioration, delamination, effects of seasonal variation, availability of different amonts of moisture, and shoulder effects

15. Ravelling Model Status: draft report completed
Primary change is broadening function of CQ factor and providing additiona guidance on its use
CQ also affected by design and climatic conditions in effect at time of paving

16. Modelling Rutting Status: draft report submitted
Addresses issues related to data collection and evaluation that affect results
Proposes component model that considers:
Initial consolidation
Structural deterioration
Surface wear
Considers estimation of RDS by RDM

17. Cracking Model Status: draft nearing completion
Re-evaluation of HDM-III models using the LTPP database
Considering single type of crack versus all and wide
Will maintain two-phase modelling

18. Other Models Drafts under development
Results will be incorporated in final report

19. 1040-6: Modelling F/T Conditions
Work performed by Lennart Djarf of Swedish Road and Transport Res. Inst.
Draft report submitted
Developped models for rutting based on studded tyres and other variables
Modelled IRI based on FI, deflection, age, and SNeff
Modelled % cracking based on traffic, width, and SNeff
Also considered maintenance efffects

20. 1040-7: Urban Conditions
Work performed by Paul Robinson of Snowy Mountains Engineering Corporation of Australia
Examined performance of polymer modified bitumens in urban environments
Draft report submitted
Suggests that some modifiers have the ability to slow crack initiation by a factor of 5. Similar effect for different polymers on rut depth progression.

21. Task 1050: Maintenance Effects Objectives
Identify common maintenance practises for flexible and rigid pavements
Develop generalised model form and logic
Quantify coefficients for the general model

22. Task 1050: Maintenance Effects
Work performed by Dr. Alex Visser and Gerrie Van Zyl from South Africa
Status: draft report submitted
Proposes immediate and long-term performance trends of different maintenance activities for a range of pavement types

23. Conceptual Example: AC surface on granular base
Roughness
Rutting
Cracking
Chip Seal
Slurry

24. Task 1060: Texture Effects
Work being conducted by Peter Cenek at Works Consultancy in New Zealand
Skid resistance/macrotexture loss for various surfaces modelled as follows:
M = M1 + M2 log (N)
Status: draft report almost completed

25. Summary Model changes minimal Guidance on usage
Incremental advancements
Extension to broader range of conditions
Some calibration with different data sets