Project TX 0-5566

1. Project TX 0-5566 UTEP - Soheil Nazarian • Imad Abdallah Strategies to Improve and Preserve Flexible Pavement at Intersections Project Duration September 08 – August 10

2. Problem Rural intersections are failing early • Damage to small vehicles • Motorists lose control of their vehicles

3. Causes for these failures High traffic volumes Heavy truck traffic Heat generated from vehicles waiting in queue Repeated vehicle turning movements and hard stops 3

4. Ranked Rural Issues Raised by TxDOT District Staff REF: Jolanda Prozzi, Robert Harrison, Jorge A. Prozzi, (2005), “Defining and Measuring Rural Truck Traffic Needs in Texas,”Center for Transportation Research, The University of Texas at Austin, Research Report 0-4169-2 4

5. Distresses (Example 1) 5

6. Distresses (Example 2) 6

7. Intersections are designed as a part of the roadway but arenot subjected to the same conditions Bottom Line 7

8. Work Plan

9. Schedule

10. Final Product

11. Outline • Problem, Schedule, Final Product • Background (Review of Literature) • Goal (Problem Statement) • Objective • Methodology • Tasks

12. Review of Literature (Task 1) Asphalt Pavement Alliance Maryland Asphalt Association National Asphalt Pavement Association National Center for Asphalt Technology Colorado Department of Transportation Canada South Africa New Zealand Illinois DOT Nevada DOT Oregon DOT Kansas DOT Common Types of Distress Remediation Action Plan

13. Most Common Distress • Rutting Structural Rutting Instability Rutting Surface/Wear Rutting

14. Other Common Distresses Fatigue Cracking Shoving Bleeding Raveling

15. Remediation Strategies • Mill and Overlay with Asphalt Concrete • Rut Filling Using Spray Patching, Micro-Surfacing • Grinding and Precision Milling • Whitetopping (Conventional and Concrete Inlay) • Ultra-Thin Whitetopping • Thin Composite Whitetopping (TCW) • Roller Compacted Concrete (RCC) • Hot in Place Recycling (HIR) • Cold in Place Recycling (CIR)

16. Action Plan • Evaluate pavement performance problems and determine the cause of major distress. • Ensure the pavement is structurally adequate. • Select and implement a cost-effective, technically sound pavement mitigation approach with appropriate materials selection and mix designs. • Practice proper construction techniques with quality assurance.

17. Example 1 After SUPERPAVE Mix 17

18. Other Examples Permeable Frictionless Coarse (PFC) Surface Course designed to Superpave Specifications Coarse Matrix High Binder (CMHB) Heavy Duty Binder Course Larger Stone Binder Course 18

19. Other Examples Stone-Matrix Asphalt (SMA) Stone Mastic Asphalt Thin Composite Whitetopping 19

20. Goal • To provide solutions that can be readily and economically carried out considering: • location of the project • construction practices • type of potential or actual damage at intersections.

21. Methodology (Expert System) Knowledge Base (Facts and Rules) User Interface Inference Engine (Draw Conclusions) Facts Expertise Explanation (Advice and Reasoning) 21

22. Tasks

23. Task 2. Understanding and Documenting Extent of Problems and Solutions in Texas • Surveying TxDOT Districts • Reviewing Forensic Reports • Interviewing district personnel and site visits • Interviewing CST personnel

24. District Interviews

25. Task 3. Selection of Candidate Sites • A least twelve sites that cover following criteria: • Type of distress observed (instability rutting vs. structural rutting) • Type of subgrade (clayey vs. sandy) • Pavement structure (two-course surface treatment vs. with HMA) • Traffic volume (rural vs. urban) • Environmental condition (east Texas vs. west Texas) • Preference will be given to sites that are scheduled for maintenance, rehabilitation or reconstruction.

26. Site Visited • Atlanta • fm 497 – fm 155 • fm 149 – fm 315 • US 259 • Laredo • fm 1472 • US 83

27. Forensic investigation Structural strength Aggregate structure Correct Asphalt Binder grade Good construction practices Task 4. Forensic Study Visited five sites and performed a thorough Investigations Site Survey, FWD, GPR, DCP, Coring, Lab Testing 27

28. Sites Visited and Investigated • Atlanta • fm 497 – fm 155 • fm 149 – fm 315 • US 259 • Laredo • fm 1472 • US 83

29. Task 5. Preliminary Guidelines Based on Results • Develop a Comprehensive Decision Tree • To guide TxDOT personnel through process of field and laboratory evaluation intersections • To select most appropriate rehabilitation solutions

30. Remediation Alternatives 30

31. Task 6. Develop Final Design and Construction Guidelines • A document that can be used as a guideline by TxDOT personnel • An electronic version of document with hyperlinks that provide additional information to TxDOT personnel

32. Task 7. Develop an Expert System • Incorporate an expert system shell. • With simple If-Then questions. • Guide through process of selecting best solution.

33. Use of the Expert System 33

34. Expert SystemVariables Window

35. Expert SystemLogic Block Window

36. Expert SystemLogic Block and Rule View Window

37. Expert SystemCorvid Browser

38. Expert SystemCorvid Browser

39. Expert SystemCorvid Browser

40. Task 8. Recommend Changes to TxDOT Policies • Based on the outcome of all tasks, recommend changes to TxDOT 2004 Specifications, if necessary.

41. Demonstrate Prototype and Show Preliminary Guideline Prototype Guideline

42. Thank you