Institute for Transportation

About the research

About the research

The objective of this research is to develop a guide for transportation practitioners that describes and evaluates the safety benefits, as shown by driver performance or other methods, of retroreflective pavement markers (RPMs), both raised and recessed, for nighttime driving, particularly during wet weather.

See the NCHRP project page for more information.

About the research

The objective of this research is to develop guidelines to improve the quality of element-level data collection for bridges on the National Highway System (NHS) in reference to the AASHTO Manual for Bridge Element Inspection.

Funding Sources:
Midwest Transportation Center
National Cooperative Highway Research Program (NCHRP) ($120,000.00)
USDOT/OST-R ($120,000.00)
Total: $240,000.00

Contract Number: DTRT13-G-UTC37

About the research

Many state and local agencies collect downward pavement imagery using highway-speed data collection vehicles. The images are subsequently processed using proprietary semi- or fully-automated crack detection and classification software to identify pavement cracking for use in asset management systems. There are multiple methods and software for defining, classifying, and reporting cracking data. In addition, these methods and the cracking data they produce are not always comparable between states, even if similar data collection and detection technologies are used. One outcome of this situation is that vendors must customize the cracking definitions for each client they serve.

In order to unify data reporting, sharing, and evaluation, standardization of pavement cracking definitions is needed. Research is needed to define cracking measurement terms for uniformity and potential standardization, building upon work done in the American Association of State Highway and Transportation Officials (AASHTO) provisional protocol (PP) 67 and 68. Additionally, research is needed to produce user and system requirements to aid in the future development of production-grade evaluation software for classifying cracking type, extent, and severity. The standard definitions will aid in sharing information among agencies and vendors as well as reporting to the Federal Highway Administration (FHWA) and setting national, state, and local performance goals.

The objective of this research is to develop standard, discrete definitions for common cracking types in flexible, rigid, and composite pavements. The definitions shall classify cracking type, extent, and severity based on information from images collected by highway-speed data collection vehicles, including orientation, length, density, displacement, location, and other relevant factors. The standard definitions shall be used to facilitate comparable measurement and interpretation of pavement cracking in the highway community. The definitions shall be of sufficient detail to serve as the basis for user and system requirements for cracking evaluation software for automated data collection. Application to both existing and emerging image-based data collection technologies shall be considered.

About the research

Implementation of geotechnical asset management (GAM) offers a significant opportunity to improve the general geotechnical practice through the development of design and management approaches that require consideration of the tradeoffs between least risk and life-cycle costs. The product from this work must be an adaptable implementation manual with the necessary template tools for an agency to recognize the benefits of GAM.

The InTrans researchers are subject matter experts on this projects.

See the National Cooperative Highway Research Program (NCHRP) project page for additional information on this project.

About the research

The objective of this research is to develop a guidebook, for use by departments of transportation (DOTs) and other agencies, on estimating transportation project preconstruction services costs. The guidebook is meant to be suitable for formal balloting and acceptance by the American Association of State Highway and Transportation Officials (AASHTO) Subcommittee on Design through the Technical Committee on Preconstruction Engineering Management and for maintenance and updating by these or other AASHTO groups.

About the research

About the research

Rumble strips are a low cost safety countermeasure used to reduce roadway/lane departure crashes. When a pavement marking is applied over the rumble pattern, it is known as a rumble stripe. The practices from state to state are not uniform and there may not be one ideal design for all applications. There are advantages and disadvantages to the different rumble designs. This synthesis will identify current practices used by states installing rumble strips and rumble stripes. The scope of this synthesis study will focus on the safety benefits, rumble design, external noise considerations, durability/maintenance issues, impacts on bicyclists, and public affairs/outreach efforts. Results will benefit government agencies, researchers, and the road-building industry in providing guidance on successful practices. This synthesis will include a literature review and a survey of state departments of transportation (DOTs) and Canadian ministries of transportation. International agencies’ experience will be reviewed as available. From the results of the survey, a minimum of three agencies will be selected and case examples of their practices will be shared. Lessons learned and gaps in information will also be covered.

Visit the Transportation Research Board’s project website.

About the research

This project summarized findings from a National Cooperative Highway Research Program (NCHRP) Innovations Deserving Exploratory Analysis (IDEA) study to develop and demonstrate the application of bio-renewable polymers for use in asphalt pavements by utilizing soybean oil through chemical synthesis. Triglyceride molecules from vegetable oils have been considered as important renewable resources, which can be used as biomonomers and be polymerized into biopolymers with properties similar to petroleum-derived monomers and polymers. In this research, non-food soybean oil was selected as a starting point to produce biopolymers. The modification effects and the effectiveness of the biopolymers were evaluated through a comprehensive asphalt binder investigation to optimize formulation of the biopolymers. Meanwhile, evaluation of the actual field performance of the biopolymer modified asphalt mixture is ongoing via the construction at the National Center for Asphalt Technology (NCAT) Test Track section.

Visit the Transportation Research Board’s project website

About the research

This report summarizes the research conducted on characteristics of the air-void system for securing long term freeze-thaw (F-T) durability of highway concrete. The work focused on three main areas:

• Investigate the hardened air-void system of in situ concrete in pavements that exhibited distress that seemed to be related to air void deficiencies
• Study the air-void systems of a wide range of concrete mixtures that could represent the mixtures employed for rigid pavement construction
• Investigate the accelerated test method for frost durability of laboratory mixtures based on a variety of test methods/variants

One observation is that finding a distressed concrete section where lack of a proper hardened air-void system was the sole factor for distress was a challenge. In most cases, air related problems were only one of the many contributors to the observed distress. Frost damage, in most cases, was manifested in joint damage and D-cracking, while the concrete exhibited acceptable performance at mid-panel.

Most of the tested cores, which were selected to represent different geographic locations, exhibited acceptable performance with a hardened air-void system with minimum air content of 4.2%, maximum spacing factor of 0.011 in., and minimum specific surface of 475 in.^-1.

Correlations were established between the parameters of the air-void system of the laboratory mixtures in fresh and hardened states. These correlations were further compared to the field observations and formed the basis for proposing criteria for minimum air requirements in concrete pavements. Results indicated that a minimum fresh air content of 5% and a super air meter (SAM) number of 0.30 can be adequate for acceptable frost durability.

Producing high clustering rates proved to be a challenge in the laboratory, even though retempering and mixing in high temperatures were considered in the test matrix. This can be regarded as a positive sign, indicating improved chemistry of the chemical admixtures that can yield more robust air-void systems.

The standard AASTHO T 161 Procedure “A” freeze-thaw tank was successfully modified to computer control to perform the conventional F-T cycling, and also the modified test. Major changes included in the modified test included a drying period prior to testing, introduction of freezing fluid to one-dimensional capillary suction, a 12-hr F-T cycle to better simulate field conditions, and the ability to evaluate performance across a range of deicer or anti-icer chemicals.

The range of test variants were evaluated across concrete mixtures with differing air-system qualities. The initially proposed 56-cycle testing duration was insufficient to observe F-T deterioration in all but the worst performing samples. Consequently, samples were tested to 140 cycles, which provided sufficient exposure to observe deterioration. Air void parameters correlated with F-T performance for six of the seven mixtures evaluated using both the AASHTO T 161 Procedure “A” (300 cycles) and CDF-A:FT1 test (140 cycles). The CDF-A:FT1 test provided differentiation for the best performing samples, where AASHTO T 161 did not. The combination of computer control, more realistic exposure conditions, F-T cycle duration, and flexibility to include deicers does suggest it would be appropriate to consider adopting the new standard.

Recommendations for future research

Based on the observations made through different steps of this research, the following knowledge gaps were identified that are recommended for future research:

• It was observed in this study that the majority of distress in pavements was related to joints and aggregates. Whether or not the interaction with the air-void system can affect the rate of deterioration remains a question. Further investigation in this area can add significant value to the current knowledge. Accelerated testing of joint performance with and without deicing salts can also elucidate the role of the air-void system in long-term durability.
• The flatbed scanner measurements present agreement with the modified ASTM C457 measurements with the fixed-focus optical microscope for chords longer than 30 microns. Deviations increase when data from all chords are considered in comparisons. This could be further investigated in the future using a variety of air-entraining admixtures that yield a wide range of air voids in concrete.
• The SAM number measurements appear to be sensitive to the chemistry of the cementitious system. The extent and mechanisms behind such variations need to be further investigated.