SWUTC Research Project Description

Title of Project:  Towards an Integrated Robust Highway Design Approach

Project Number:  167274

Principal Investigator:
Jorge Prozzi
(512) 232-3488
P.I. Affiliation:  University of Texas at Austin

Project Monitor:
Dario Perdomo
Zachry Construction Co.
(210) 554-3804

Project Status:  Active

Date Started:  9/1/07

Estimation Completion Date:  8/31/08

Estimated Cost - Current Fiscal:  $40,000

Estimated Cost - Total Planned:  $40,000

Project Summary:
Project Abstract:
Highways are designed and built following a multi-phase process that includes: material selection, structural design, construction, acceptance, and management. These phases are currently carried out independently and, therefore, the entire process is not optimal. This project will develop a set of fundamental guidelines towards an integrated highway design approach, which will involve all phases described above and all main players involved in the process. The key for success will be the development of more robust designs that use locally available resources, are easier to build and to inspect, and therefore result in a final product of consistent quality. This will be achieved by involving all relevant parties in the development of the guidelines.

Project Objectives:
This project will produce fundamental guidelines to develop integrated and robust highway designs. This objective will be achieved by involving material providers, designers, construction companies, equipment manufacturers, engineering consultants, highway concessionaires, state, federal and other highway agencies. The key for success will be the identification of the aspects that have the largest potential for resulting in more robust designs that (i) use locally available resources and recycled materials, (ii) are easier to build and to inspect, and (iii) result in a final product of consistent quality. Thus, the design focus will shift from producing the most economical highway structural design that meets the required traffic demand to the production of the optimal highway structure that is effective, efficient, constructable, sustainable and durable.

The design optimization will be achieved by integrating all phases involved in the life-cycle of the highway including material selection, design, construction, acceptance, and management. Generalized costs will be considered that, for instance, will put a premium on using local and recycled materials, equipment-friendly designs, and final products that are easy to inspect or whose inspection could be automated to some extent. Consistent quality is expected to be the main feature of these designs.

Task Descriptions:
Task 1: Literature Review and Interviews
A literature review will be conducted to find out whether similar approaches have been attempted previously. The literature review will focus on the use of marginal and recycled materials but will be extended to other aspects that can results in more robust or forgiving designs.

In addition to the literature review, interviews with highway agencies, consultants and contractors will be carried out to establish the critical material characteristics and pavement structural properties that can be relaxed without compromising the performance of the pavement. 

Task 2: Determination of Critical Characteristics/Properties
Based on the findings from Task 1 and preliminary analyses, critical material characteristics and pavement properties will be identified for further evaluation. These preliminary analyses will consist of structural evaluation and performance predictions based on empirical and mechanistic principles. For the empirical part, the AASHTO Guide for the Design of Pavement Structures will be used. For the mechanistic counterpart, the recently developed Mechanistic Empirical Pavement Design Guide will be used. 

Task 3: Sensitivity Analysis to Evaluate Expected Performance
Once the critical material characteristics and pavement properties are identified and analyzed, a comprehensive sensitivity analysis will be conducted. This sensitivity analysis will focus on current design and construction practices in the Southwestern United States and the corresponding environmental conditions prevailing in the region.

The sensitivity analysis will enable the quantification of the relaxation of current specifications under diverse environmental and traffic conditions. With these results in hand, the second part of the sensitivity analysis will consist of identifying the measures to counteract the effects on performance of using substandard materials (or out-of-specification materials). These countermeasures may include the design of thicker layers or the inclusion of additional layers. It should be kept in mind that this will be accompanied by an economic analysis to verify that the new solution is comparable to the original one.

Task 4: Evaluation of Results and Development of Recommendations
During Task 4, the results of the previous task will be analyzed and compared with observations available from the Long-Term Pavement Performance Studies (LTPP). This exercise will provide the practical validation of the sensitivity analyses.

Once the results are validated, a set of recommendations will be developed that will allow a departure from the original basic structural design and material specifications without compromising either the integrity of the pavement or its expected performance. It is expected that this approach would be initially implemented for lower volume highways such as the Farm-to-Market network in Texas.

Task 5: Reporting and Technology Transfer
The findings of this project will be summarized and reported in this task. This task will also include the preparation of the material to be used for technology transfer purposes.

Index Terms:
Pavement Design, Pavement Construction, Quality Control, Performance Monitoring