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O PTIMIZED P AVEMENT D ESIGN W ITH R ESPECT TO Q UALITY AND E CONOMY

O PTIMIZED P AVEMENT D ESIGN W ITH R ESPECT TO Q UALITY AND E CONOMY. J. Litzka. Institute for Road Construction and Maintenance Vienna University of Technology. General objective of pavement design. Structural efficiency during the whole design period Based on given random conditions.

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O PTIMIZED P AVEMENT D ESIGN W ITH R ESPECT TO Q UALITY AND E CONOMY

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  1. OPTIMIZED PAVEMENT DESIGNWITH RESPECTTOQUALITY AND ECONOMY J. Litzka Institute for Road Construction and MaintenanceVienna University of Technology

  2. General objective of pavement design • Structural efficiency during the whole design period • Based on given random conditions • Design traffic load • Bearing capacity of subgrade • Material properties of pavement layers 2 J. LITZKA - OPTIMIZED PAVEMENT DESIGN WITH RESPECT TO QUALITY AND ECONOMY

  3. For routine application (1) • Average or minimum values of • Subgrade • Material properties and fatigue behaviour • Pavement design according to given design traffic (load class) • e.g. catalogue type (like Austrian RVS 3.63, based on analytical calculations) 3 J. LITZKA - OPTIMIZED PAVEMENT DESIGN WITH RESPECT TO QUALITY AND ECONOMY

  4. For routine application (2) • Resulting in a number of technically equivalent pavement solutions • Based on availability of materials and/or on cost comparison the optimal solution can be selected together with possible alternatives • But still a general solution based on plausible assumptions, not always most cost effective 4 J. LITZKA - OPTIMIZED PAVEMENT DESIGN WITH RESPECT TO QUALITY AND ECONOMY

  5. Design table RVS 3.63, bituminous pavements 5 J. LITZKA - OPTIMIZED PAVEMENT DESIGN WITH RESPECT TO QUALITY AND ECONOMY

  6. Possible improvement of economic efficiency (1) • Specific analytical design using the underlying procedure for the catalogue, but • Real given values of bearing capacity of subgrade, material characteristics of layers, specific fatigue laws • Also possibility to include new, innovative, not standardised materials 6 J. LITZKA - OPTIMIZED PAVEMENT DESIGN WITH RESPECT TO QUALITY AND ECONOMY

  7. Possible improvement of economic efficiency (2) Example 7 J. LITZKA - OPTIMIZED PAVEMENT DESIGN WITH RESPECT TO QUALITY AND ECONOMY

  8. s (t) e (t) Essential precondition • Exact and reliable information about input characteristics • Performance orientated laboratory tests (stiffness modulus, fatigue behaviour etc.) • Traffic forecast of high accuracy 8 J. LITZKA - OPTIMIZED PAVEMENT DESIGN WITH RESPECT TO QUALITY AND ECONOMY

  9. Benefits of specific pavement design • Better adaptation to existing subgrade situation • Better utilisation of material properties • Possibility for innovative materials and solutions • Alternative bids • Performance related contracts 9 J. LITZKA - OPTIMIZED PAVEMENT DESIGN WITH RESPECT TO QUALITY AND ECONOMY

  10. but: Do not overlook the right moment Further advantage of specific analytical design • Stage by stage construction • Stage 1 as basic solution for first part of design period • Stage 2 designed based on existing layer properties and realistic design traffic • Better reliability and also acting as maintenance procedure 10 J. LITZKA - OPTIMIZED PAVEMENT DESIGN WITH RESPECT TO QUALITY AND ECONOMY

  11. Consideration of costs • Construction costs • Life-cycle costs • Construction • Maintenance • Routine • Rehabilitation including • Traffic management at construction sites • Methods/measures • Intervals • Additional user costs (e.g. time loss) • Environmental costs (possibly) 11 J. LITZKA - OPTIMIZED PAVEMENT DESIGN WITH RESPECT TO QUALITY AND ECONOMY

  12. Calculation of life-cycle costs • Prognosis of development of pavement condition necessary • Prediction of life time, change of condition indicator-values and thus prediction of time and type of maintenance measure Basic tasks for PMS/e.g. VIAPMS 12 J. LITZKA - OPTIMIZED PAVEMENT DESIGN WITH RESPECT TO QUALITY AND ECONOMY

  13. Change of approach and responsibilities Actual: • Only construction costs considered • Client chooses contractor according to cost comparison • Sometimes alternatives compared New approach (even if normal tender): • Consider life-cycle costs • At least for road owner costs (construction and maintenance) 13 J. LITZKA - OPTIMIZED PAVEMENT DESIGN WITH RESPECT TO QUALITY AND ECONOMY

  14. For functional contracts (PPP) • Responsibility of concessionaire/contractor to consider • Complete life-cycle costs • Including additional user costs • (e.g. loss of toll/fee during rehabilitation works, closures) • Normally compliance with trigger values of pavement condition required 14 J. LITZKA - OPTIMIZED PAVEMENT DESIGN WITH RESPECT TO QUALITY AND ECONOMY

  15. Functional contracts - example 5,0 Threshold level V very poor 4,5 4,0 IV poor Warning level 3,5 3,0 III fair condition index CI [-] 2,5 2,0 II good 1,5 I very good 1,0 condition class 35 5 10 15 20 0 technical parameter [mm] 15 J. LITZKA - OPTIMIZED PAVEMENT DESIGN WITH RESPECT TO QUALITY AND ECONOMY

  16. Most crucial point: Performance models • Standard- type pavements, traditional materials • Empiric results from database analysis • But still more risks compared with routine application within maintenance planning • Starting from new pavement • No calibration of performance models to actual measurements possible 16 J. LITZKA - OPTIMIZED PAVEMENT DESIGN WITH RESPECT TO QUALITY AND ECONOMY

  17. Most crucial point: Performance models (2) • Innovative, new materials and pavements • Prognosis based on analytical calculation • First assumption based on existing empiric functions and adaptation by periodic condition measurements (normally required in any case) With this also required minimum quality of road condition secured 17 J. LITZKA - OPTIMIZED PAVEMENT DESIGN WITH RESPECT TO QUALITY AND ECONOMY

  18. Optimized solution • Construction costs • Maintenance costs including additional user costs Minimum life-cycle costs • Most economic solution • In compliance with given quality requirements 18 J. LITZKA - OPTIMIZED PAVEMENT DESIGN WITH RESPECT TO QUALITY AND ECONOMY

  19. Development Pavement Condition – Concrete Pavement Threshold Level Concrete Pavement Exchange of distressed slabs and thin bit. overlay Bit. Base Course Subbase Warning Level 19 J. LITZKA - OPTIMIZED PAVEMENT DESIGN WITH RESPECT TO QUALITY AND ECONOMY

  20. Wearing Course Threshold Level Bit. Base Course Overlay Reinforcement Base Course Subbase Warning Level Development Pavement Condition – Asphalt Pavement Total thickness according to design 20 J. LITZKA - OPTIMIZED PAVEMENT DESIGN WITH RESPECT TO QUALITY AND ECONOMY

  21. Wearing Course Threshold Level Reinforcement (2nd construction stage) Bit. Base Course Base Course Overlay Subbase Warning Level Development Pavement Condition – Asphalt Pavement 2-stage pavement construction 21 J. LITZKA - OPTIMIZED PAVEMENT DESIGN WITH RESPECT TO QUALITY AND ECONOMY

  22. Overlay Replacement of distressed slabs and thin overlay Overlay Reinforcement Reinforcement (2nd construction stage) Comparison Total Costs (including user costs) 22 J. LITZKA - OPTIMIZED PAVEMENT DESIGN WITH RESPECT TO QUALITY AND ECONOMY

  23. Conclusions (1) Optimized pavement design necessary with respect to • Increased traffic loads • Limited budgets • Saving of resources • Minimised impact to road users (important for toll roads) 23 J. LITZKA - OPTIMIZED PAVEMENT DESIGN WITH RESPECT TO QUALITY AND ECONOMY

  24. Conclusions (2) Optimized pavement design possible by applying • Improved design methods • Improved materials • Long life, modular pavements • Improved construction quality (very important) 24 J. LITZKA - OPTIMIZED PAVEMENT DESIGN WITH RESPECT TO QUALITY AND ECONOMY

  25. Conclusions (3) Optimized pavement design necessary and possible if • Normal contract • Administration responsible for design and maintenance • Functional contracts (PPP) • Concessionaire responsible for design, construction and maintenance over the full concession period together with guaranteed remaining lifetime after termination of contract 25 J. LITZKA - OPTIMIZED PAVEMENT DESIGN WITH RESPECT TO QUALITY AND ECONOMY

  26. Conclusions (4) For optimized pavement design necessary in any case • Improved, innovative materials • Improved, performance related laboratory tests • High quality of construction • Optimal maintenance organisation and Enough time for development of alternative solutions and attributed laboratory tests and calculations during the bidding process 26 J. LITZKA - OPTIMIZED PAVEMENT DESIGN WITH RESPECT TO QUALITY AND ECONOMY

  27. Thank you for your attention 27 J. LITZKA - OPTIMIZED PAVEMENT DESIGN WITH RESPECT TO QUALITY AND ECONOMY

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