Long-Term Pavement Performance Compliance With Department of Transportation Information Dissemination Quality Guidelines
CHAPTER 6. IMPROVEMENT OPPORTUNITIES
This document demonstrates the LTPP program's focus on data quality in relationship to the DOT IDQG issued more than 10 years after the start of the LTPP program. While the LTPP program is proud of its record on data quality issues, this quality focus also results in identification of improvement opportunities. Implementation of these improvements is highly dependent upon program funding.
The improvement opportunities are organized and presented using the main topic areas contained in the DOT IDQG.
Planning Data Systems
The current date for the end of the LTPP program is 2009. No changes to this portion of the program are anticipated.
Collection of Data
Although LTPP data collection operations have reached a mature stage, improvement opportunities currently identified by the program for possible implementation include the following:
- Introduction of new technology to collect previously collected data in a more efficient manner. An example is using instrumentation to automatically measure and record pavement gradient temperatures previously measured and recorded using a manual method. Another example is the use of LiDAR (Light Detection and Ranging) based profile technology, which provides an integrated measurement of both the transverse and longitudinal profile of a pavement.
- Issuance of a new contract for the collection of pavement surface distress permanent image records and interpreted distresses. The contract for this data collection operation expired in 2003 and has not been renewed due to a lack of funds. This data collection effort was rated a top priority from a peer review by the TRB LTPP Committee.
- Increased coverage of nondestructive measurements of within-section pavement thickness using ground penetrating radar. A limited number of measurements were previously performed on high priority sites due to budget considerations.
- Better characterization of the drainage related features at test sites which encompass geomorphologic, topographic, and engineered characteristics.
- Use of more advanced material characterization methods. The LTPP program is collaborating with other FHWA teams to develop a test protocol for using indirect tensile test methods to measure the dynamic modulus of AC from core samples obtained from in-service pavement test sections. The Mechanistic-Empirical Pavement Design Guide (http://www.trb.org/mepdg/guide.htm) developed by NCHRP uses this material property for characterization of the elastic modulus of AC mixtures. Measurement of this property from field samples did not exist when LTPP began, and no formal measurement protocol has yet to be developed and accepted by the industry.
- Use of LTPP-managed funds to collect missing data previously assigned as the responsibility of participating highway agencies. As a result from a previous assessment of the LTPP program, the lack of traffic data and materials data from SPS project sites was identified as a critical area for improvement. These efforts are contingent on funding.
- A pooled fund study was established to address missing traffic data issues.
- LTPP program funds were reappropriated to obtain and test material samples from priority SPS project sites to fill in the gaps of missing data, add measurements from new tests, and provide more time sequence material properties.
This is an area where LTPP has internally documented improvement opportunities that have not been implemented due to dwindling budget resources. They include the following:
- Addition of computed parameters to the database to fill missing data gaps or add new parameters that is potentially useful to data users.
- Estimation of pavement temperature profile during FWD testing when measured data are not available.
- Estimation of load transfer efficiency from FWD tests.
- Estimation of faulting in PCC pavements from longitudinal profile measurements.
- Imputation of time based PCC material properties, such as the 28 day compressive strength.
- Estimation of the dynamic modulus of AC mixes using empirical models and agency supplied data.
- Estimation of joint opening from transverse joint gauge length measurements.
- Interpretations of instrumentation measurements to provide estimates of frost depth locations and moisture contents in subsurface layers.
- Improved automation to data error detection and editing software. Many of the legacy data edit programs need to be upgraded to current software platforms.
- Increased use of codes and controlled vocabulary for comment fields. While some comment fields will always need to be retained as free form entries, work is needed to clean up those fields which can be codified and subjected to vocabulary control.
- Application and adaptation of changes to standardized coding schemes.
- Requirements that analysis contractors include in their proposals a detailed discussion of their analytical approach, statistical assumption tests proposed for use, statistical deviations to be examined, and statistical sensitivities to be evaluated in their approach. It is noted that this requirement can increase the cost of proposal preparation. It also requires that proposal review panels contain expertise, experience, and training to adequately evaluate proposed statistical approaches.
- Develop data analysis contractor guidelines in conformance with DOT guidelines on statistical approaches and wording of the interpretation of statistical test outcomes.
- Develop data analysis peer review guidelines in conformance with DOT guidelines on statistical approaches and wording of the interpretation of statistical test outcomes.
Dissemination of Information
In the last years of the LTPP program, improvements to information dissemination have been planned as a priority focus area. Some opportunities for improvements include the following:
- Improvements to uncertainty statements in measurements and statistical interpretations for traffic monitoring data.
- Improved access to updated planning documentation, collection, processing, and analysis methodology.
- Improvements in source and accuracy statements that accompany the data.
- Improved data user aids that simplify access to data stored in the LTPP relational database structure, including development of views and data user training aids.
- Development of a training course for data users.
- Use of technology advancements to improve data delivery, such as Web-based database servers optimized for delivery of large data sets.
Evaluating Information Quality
The LTPP program intends to continue its established practices relative to evaluation and improvement of data quality. At this time, the only recognized opportunity for improvement is the enhancement of documentation for user notification of data errors.