Performance Specifications Strategic Roadmap: A Vision for the Future
Appendix 1. Postscript
Since FHWA floated the idea of creating a Performance Specification Road Map, one national workshop, two Technical Working Group Meetings, two Expert Task Group meetings, and many hours of internal staff meetings have taken place. Following is a summary of accomplishments, decisions, etc., that led to the development of this Road Map.
In May 2000, under the sponsorship of FHWA and the Florida DOT, approximately 50 attendees from industry, academia, and transportation agencies met to discuss performance-related specifications. At this time, little research or implementation was occurring. Meeting attendees supported the continued research and implementation of PRS and the concept of a national organization to manage the process. The attendees identified PRS "rules" to help focus on key elements of a PRS structure.
The group also noted that many DOTs were expressing interest in warranties. Warranties were considered another option for addressing product performance and quality issues. Finally, the group raised awareness that the issue of method specifications should be discussed along with performance requirements.
Technical Working Group
Two Technical Working Group meetings were held, one in 2001 and another in 2002. The working group focused on establishing expert task groups and reviewing progress in both the concrete and asphalt PRS programs. The group recommended a management structure, and discussed the application of PRS to items such as bridge decks, traffic striping, geotechnology, pavement preservation, and traffic maintenance through work zones. The group recognized that each topic required a different approach to PRS and that the models/life cycle cost analysis approach developed under the concrete pavement PRS may not apply to other products. The working group helped distinguish between warranties and PRS in further detail and strongly recommended tracking warranties along with PRS activities. The group also recommended developing a newsletter and brochure to advise senior management about the program. They cautioned that the "black box" concept of models was a difficult concept and that clear management tools were needed. The group also evaluated a matrix concept that showed different specification structures for method, end result, PRS, and warranty specifications. The group acknowledged that to really create an atmosphere for innovation, method specifications might have to be relaxed. All agreed that this has many potential downside risks.
The Technical Working Group also recommended that the expert task groups for asphalt and concrete pavements be combined into one group because the structures are similar, differing only in the specific distresses addressed.
Concrete Pavement Expert Task Group
When the Concrete Pavement Expert Task Group met in July 2002, it thoroughly reviewed the work done by FHWA and the Indiana DOT to develop and evaluate the PRS jointed-pavement specification. The PRS, known as PaveSpec 3.0, includes transverse cracking, transverse joint spalling, faulting, and smoothness as the performance drivers. The INDOT evaluation process has been well documented and includes some of the most insightful details yet compiled on a PRS specificion. The models/life cycle cost analysis approach was effective in helping INDOT and the contractors focus on the impact that material and construction characteristics may have on long-term quality.
The expert task group developed a detailed list of further research needed to continue to develop the PaveSpec 3.0 PRS. The more strategic recommendations include the following:
- Development of a continuously reinforced concrete pavement PRS.
- Development of a concrete overlay PRS and building of new design models developed for whitetopping and ultra-thin whitetopping.
- Conversion of the PaveSpec 3.0 models to the 2002 Design Guide models.
- Better display of the maintenance rehabilitation decision tree.
- Development of additional quality characteristics, including tie bars, dowel bar alignment, saw-cutting factors, durability (scaling, mix optimization issues), temperature gradient issues, and drainage. These elements need to be prioritized.
- More thorough examination of models limitations.
- Additional development of rapid, non-destructive testing procedures for construction control and measurement.
- Advanced LCCA model, including a more robust user cost module.
- Further development of a guide specification that addresses the relationship between PRS and method specification language. Included would be a thorough review of the specification matrix recommended for development by the Technical Working Group.
- Development of outreach efforts.
Asphalt Pavement Expert Task Group
The National Cooperative Highway Research Program is developing the asphalt pavement PRS under Project 9-22. In the 1990s, FHWA and AASHTO sponsored a series of research projects to develop a PRS for hot mix asphalt (HMA). In February 2000, the WesTrack project delivered an HMA PRS in the form of an alpha-tested version of a computer program that incorporated advanced performance-prediction models for HMA and a guide specification. The alpha version of the HMA PRS included two application levels. Level I was based on material and construction properties (e.g., asphalt content; gradation; field-mixed, laboratory-compacted volumetrics; in-place air voids; and ride quality) now obtained by public agencies for materials-and-method, end-result, and quality control/quality assurance types of specifications. Direct regression equations relating these properties to pavement performance (specifically, permanent deformation and fatigue cracking) exhibited in the WesTrack experiment were the primary basis for calculating pay factors in the Level I HMA PRS.
The Level II HMA PRS uses a more sophisticated, mechanistic-empirical analysis of the results of laboratory performance tests, as well as the WesTrack property-performance relationships, to determine pay factors. Regardless of whether the Level I or Level II performance model is used, the HMA PRS calculates pay factors by comparing the life cycle cost of the as-designed and as-built projects. This method is a significant improvement over current specifications, as the HMA PRS provides tools for objective calculation of equitable, consistent pay factors and mirrors the concrete pavement PRS specification.
The project included two phases. The first called for a comprehensive beta test program for the HMA PRS software and field trials. The second called for integrating the HMA performance models from the 2002 Pavement Design Guide into the HMA PRS software. The revised software package should be available in early 2004 for further field evaluation.
The Technical Working Group recommended that the asphalt PRS and the concrete PRS be managed together in one expert task group. The group should provide guidance on field evaluations, communication documents, and training, as well as work to keep the specification structures the same.
Pavement Preservation Expert Task Group
The Pavement Preservation Expert Task Group met in October 2002. It was the first time this subject had been discussed formally by a DOT-industry group. The group noted that the concrete and asphalt PRS specification structures were not really applicable to the typical pavement preservation structure. Little to no modeling research has been done in this area, hindering the ability to make predictions. In addition, many DOTs have skipped the PRS approach and jumped to material and workmanship warranties. The group recommended the following:
- Pavement preservation topics should be divided into smaller, more workable subject areas, such as microsurfacing, chip seals, surface treatments, fog seals, etc.
- End-result specifications should be developed for one topic, e.g. chip seals, that address using new test procedures and reducing method specification requirements.
- The matrix approach should be used to develop specification options.
- An incentive-based warranty guideline specification should be developed to determine if it would help create a better bidding environment and more innovation in the process.
Other Expert Task Groups
Plans are being developed to implement expert task groups for geotechnology work items and bridge components. This work should be addressed in late 2003.
FHWA also has plans to initiate a Work Zone Safety Expert Task Group. This work will probably lead to yet another variation of the performance specification theme: quality of services received.
Finally, other organizations are examining the use of functional specifications for maintenance contracts. These contracts could blend PRS, service performance, and even warranty specifications into one contract.
Other National Research and Planning Efforts
The PS topic has been addressed in many national research planning documents. The 2002 Construction Engineering and Management Research Program (NCHRP Web Document #51) supports a major initiative in performance-related specifications and rapid non-destructive testing programs. Research on incentives, warranties, performance specifications, and a risk manual have been proposed for inclusion in the plan for Research on Accelerating the Renewal of America's Highways (Renewal). Iowa State University, under a cooperative agreement with FHWA, is developing a detailed program to further advance PRS under the Long-Range Concrete Pavement Research Plan.
In addition, research continues to be conducted with the focus on performance of certain elements of the highway system. The Transportation Research Board Web site6 outlines research on the following topics:
- NCHRP 453, Performance-Related Tests of Aggregates for Use in Unbound Base Pavement Layers
- NCHRP 1-19(2), Validation of Performance-Related
- Tests of Aggregates for Use in Hot-Mix Asphalt Pavements
- New England Transportation Consortium, Relating Hot Mix Asphalt Pavement Density to Performance
- Louisiana Transportation Research Center, Performance-Related Test for Asphalt Emulsion
- FHWA, Investigation of Aggregate Shape Effects on Hot Mix Performance using an Image Analysis Approach
- National Center for Asphalt Technology (NCAT), Accelerated Testing of Asphalt Pavements Test Road
- FHWA et al, Accelerated Performance-Related Test Facilities
The Technical Working Group-indeed, the entire transportation community-needs to understand and integrate the output of these and many other studies.