1. KINGDOM OF SAUDI ARABIA Arriyadh Development Authority RIYAD المملكة العربية السعودية اله ـ ي ـــ ئ ـ ة العلي ــ ا لتطوي ـ ر مدينة الري ـ اض ASSOCIATED CONSULTING ENGINEERS

4. Prince Turkey Underpass Takhassussi Underpass King Fahd Tunnel Olaya Tunnel Prince Ahmad Intersection King Abdul Aziz Underpass

5. Project Phases

6. Detour of Classical Construction

7. Top-Down Construction Methodology The “Top-Down” construction approach was primarily devised for existing structures short of space (parking, offices, utilities etc..) such as the existing building may remain in place and its activities uninterrupted while the additional construction works and expansion is happening beneath it. Later it was adopted to other construction industries such as highways, bridges, and even new buildings where significant benefits may be achieved by adding the ability to proceed with construction in both directions at the same time, starting at the ground surface. In existing buildings or structures, where appreciable loads are present on the existing foundations, micropiles will be required to retain the sides of the excavation and to transfer the vertical loads onto a new bearing stratum taking into consideration differential settlement and its effects on the structure. Normally such works are very sensitive and require high technicity and expertise.

8. Design principle Step One: Drill the 60 cm piles, 150 cm on centers, install the piles reinforcement cage, and cast concrete up to the bottom level of the (60x146) pile cap.

9. Step Two: Install the reinforcement cage of the (60x146) pile cap. Design principle

10. Step Three: Cast 20 cm of the 146 cm depth of the pile cap to provide seating for the pre-cast pre-stressed beams. Design principle

11. Step Four: Place the (60x100) pre-cast pre-stressed beams, seated 3 cm on the 20 cm cast portion of the pile cap. One beam is placed every 150 cm, i.e. one per pile. Design principle

12. Step Five: Lay the 6 cm pré-dalle seated 3 cm on the top of the pre-cast pre-stressed beams. Design principle

13. Step Six: Place the reinforcement of the 20 cm topping slab, anchored in the pile cap reinforcement cage. Design principle

14. Step Seven: Cast the topping slab along with the pile cap. Design principle

15. Top-Down Construction Stages

16. A view of the area just underneath the building showing the light on the other side Top-Down Construction Applied to Existing Buildings

17. Top-Down Construction Applied to Existing Buildings View of the building’s façade

18. Utility Detour

19. Proposed Detours Duration: 18 days (100 piles and 2 drilling machines) Lanes lost: 1 lane of the service road for each direction

20. Proposed Detours Duration: 18 days (100 piles and 2 drilling machines) Lanes lost: 1 lane of the service road for each direction

21. Proposed Detours Duration: 18 days (100 piles and 2 drilling machines) Lanes lost: Zero (Compensated by the median between service road & freeway)

22. Proposed Detours Duration: 18 days (100 piles and 2 drilling machines) Lanes lost: Zero (Compensated by the median between service road & freeway)

23. Proposed Detours Duration: 15 days drilling (80 piles) & 20 days slab works Lanes lost: zero PILES DRILLING STAGE 5 SLAB WORKS STAGE 1

24. Proposed Detours Duration: 20 days excavation Lanes lost: Zero SLAB WORKS STAGE 2

25. Proposed Detours STAGE 3 FREEWAAY WORKS AFTER INTERSECTION IS REINSTATED

26. Proposed Typical Sections 1

27. 4 Typical section At underpass Proposed Typical Sections

28. 8 Proposed Typical Sections

29. 11 Proposed Typical Sections

30. Typical Sections 12 Proposed Typical Sections

31. 13 Typical section At tunnel Proposed Typical Sections

33. Design Criteria

34. Design Criteria

35. Design Criteria

36. Design Criteria

37. Design Criteria

41. Microscopic Simulation

42. Microscopic Simulation

43. Microscopic Simulation

44. Microscopic Simulation

45. Microscopic Simulation

46. Microscopic Simulation

47. PM: 1 Lane Microscopic Simulation