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

Problem Rural intersections are failing early Damage to small vehicles Motorists lose control of their vehicles Causes for these failures: 1. High traffic volumes 2. Heavy truck traffic 3. Extended periods of high ambient temperatures 4. Heat generated from vehicles waiting in queue 5. Repeated vehicle turning movements and hard stops 2

Goal of the Project 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. 3

Objectives Through surveys document types of distress that are present throughout Texas Categorize sources and layers that contribute to damage at intersections. Select a number of statistically-valid, representative intersections of each category. Evaluate selected locations to define best solution. 4

Work Plan 5

Schedule 6

Outcome Develop maintenance and rehabilitation guidelines for intersections with problems. Develop (minimum) pavement design for rural and urban intersections. Develop draft specifications for flexible pavement construction for rural intersections. 7

Final Product 8

Task 1. Information Search and Collection Literature Review. Search for nationwide and international electronic documentation of practices for mitigating rutting at intersections. 1. TxDOT online pavement design guide provides information about the design of intersections with hot mix and concrete overlays. 2. Illinois DOT, as well as Colorado, Oregon, Maryland, and Kansas DOTs 9

Task 1. Cont. International Effort The Federation of Canadian Municipalities and Canadian National Research Council. International Bank for Reconstruction and Development (IBRD) - Low Cost Design Standards for Rural Roads Projects. The Association of State, Territory and Federal Road and Traffic Authorities in Australia. The Southern African Development Community (SADC). 10

Task 1. Outcome (Jan2009) 1.Documentation of practices for mitigating rutting at intersections worldwide 2.A matrix of solutions that enumerates at a minimum the following items: Under what traffic volume, environmental condition, pavement structure the solution is effective? Which alternative is appropriate for maintenance, rehabilitation or reconstruction? What are the advantages and disadvantages of each solution? What is the cost-benefit of the solution? How adaptable the solution is to TxDOT operation? 11

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 12

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. 13

Task 4. Forensic Study Structural and functional evaluation of sites Trenching, coring and sampling Laboratory tests of pavement materials Recommending solutions Conducting thorough structural design of existing and recommended solutions Life Cycle Cost Analysis of solutions 14

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 15

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 16

Task 7. Develop an Expert System Incorporate an expert system shell. With simple If-Then questions. Guide trough process of selecting best solution. 17

Task 8. Recommend Changes to TxDOT Policies Based on the outcome of all tasks, recommend changes to TxDOT 2004 Specifications, if necessary. 18

Task 9. Submit Reports Technical memorandum at the end of each task. Final Report documenting all work performed, method used, and results achieved. A Project Summary Report (PSR). 19

Thank you 20