U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
202-366-4000
Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations
| REPORT |
| This report is an archived publication and may contain dated technical, contact, and link information |
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| Publication Number: FHWA-HRT-11-070 Date: July 2012 |
Publication Number: FHWA-HRT-11-070 Date: July 2012 |
FHWA and State highway agencies have learned from opinion polling that U.S. drivers value the quality of their ride experience. Over the past three decades, concrete pavement engineers have focused on improving pavement smoothness without jeopardizing surface friction or surface drainage characteristics. This difficult but important balancing act has led to advancements in smoothness indices, longitudinal tining, and measurement equipment, among other areas. However, the relationship between surface texture and surface characteristics, as well as concrete pavement performance, has yet to develop fully. While smoother concrete pavements are being constructed, the relationships between texture, noise, splash and spray, and friction require further study before widely accepted solutions become available.
In some areas of the United States, drivers and residents have demanded quieter rides and living experiences. These demands often eliminate concrete pavement as a construction option, and, in some cases, has even led to the overlay of recently constructed concrete pavements. In the Phoenix, AZ, metropolitan area, concrete pavements that have a harsh transverse texture are used to make up nearly all of the freeway system. Because of noise complaints, these pavements have now been largely overlaid with an asphalt rubber friction course. While this may seem radical to some, the approach is not new. Noise has been a major problem in some of the most densely populated areas of Europe for more than two decades. As a result, concrete pavement construction has been impeded there.
Most European nations now place thin asphalt-based wearing courses over their concrete pavements immediately after construction. However, some concrete surfacing solutions have been used successfully. These include thin, open-graded (porous) concrete wearing surfaces and exposed aggregate surfaces. Textures such as fine longitudinal burlap drag and diamond grinding are also used to reduce noise.
To address noise impacts to highway abutters, FHWA regulations currently dictate the noise mitigation efforts required, if any, for new or expanded highway facilities on the Federal aid system. To date, these regulations have resulted in questions about whether noise barriers are necessary and, if so, what their design should be. At the same time, automobile and tire makers have developed designs that meet more stringent friction (braking) demands while also reducing interior noise. In the near future, pavement will be looked at to help reduce noise. This will require concrete pavement engineers to take responsibility for finding innovative materials and optimizing pavement textures.
To meet this responsibility, concrete pavement engineers must balance smoothness, friction, surface drainage, splash and spray, and noise to develop economical and long-lasting solutions for concrete pavement surfaces. Any long-term solution must include research and experimentation that examines the integration of these elements into an array of viable incremental solutions. One consideration is developing standardized noise measurement and analysis techniques. Pavement engineers must also understand fundamental engineering properties better to assess noise, friction, and smoothness; isolate improved texturing options; and tailor solutions to location, traffic, and renewal requirements. Pavement engineers must understand the functional and structural performance of various solutions over time, as the data from many studies are sufficient to examine the relationships between noise and the other surface characteristics, including pavement durability.
Research must aim to develop various standardized measurement techniques, understand the tire-pavement interaction with various texturing options, predict the life expectancy of any solution, and identify possible repair and rehabilitation strategies for these pavements. Moreover, if noise criteria are ever imposed as design-build criteria, integration with national noise mitigation standards must be considered, and rational and achievable construction specification language must be developed.
The following introductory material summarizes the goal and objectives for this track and the gaps and challenges for its research program. A table of estimated costs provides the projected cost range for each problem statement, depending on the research priorities and scope determined in implementation. The problem statements, grouped into subtracks, follow.
A better understanding of concrete pavement surface characteristics will provide the traveling public with concrete pavement surfaces that meet or exceed predetermined requirements for friction/safety, tire-pavement noise, smoothness, splash and spray, light reflection, rolling resistance, and durability (longevity).
Track 4 objectives are as follows:
Track 4 research gaps are as follows:
Track 4 research challenges are as follows:
Table 18 shows the estimated costs for this research track.
| Problem Statement | Estimated Cost |
| Subtrack 4-1. Concrete Pavement Texture and Friction | |
| 4-1-1. High-Speed Three-Dimensional Macrotexture Assessment Equipment | $2–$5 million |
| 4-1-2. In Situ Three-Dimensional Microtexture Assessment Equipment | $500,000–$1 million |
| 4-1-3. High-Speed Three-Dimensional Microtexture Assessment Equipment | $2–$5 million |
| 4-1-4. Behind-the-Paver Texture-Sensing Equipment | $250,000–$500,000 |
| 4-1-5. Multidimensional Concrete Pavement Friction Assessment | $1–$2 million |
| 4-1-6. Unified Concrete Pavement Texture and Friction Model | $500,000–$1 million |
| Subtrack 4-2. Concrete Pavement Smoothness | |
| 4-2-1. High-Speed, High-Resolution Three-Dimensional Pavement Profiling | $2–$5 million |
| 4-2-2. Next Generation Concrete Pavement Smoothness Index Development and Specifications | $500,000–$1 million |
| 4-2-3. Behind-the-Paver Smoothness Sensing Equipment | $100,000–$250,000 |
| 4-2-4. Design and Construction Guidelines to Improve Concrete Pavement Smoothness | $500,000–$1 million |
| Subtrack 4-3. Tire-Pavement Noise | |
| 4-3-1. Standardized Tire-Pavement Noise Measurement | $1–$2 million |
| 4-3-2. Standardized Vehicle Interior Noise Measurement | $250,000–$500,000 |
| 4-3-3. Tire-Pavement Noise Thresholds | $500,000–$1 million |
| 4-3-4. Behind-the-Paver Noise Sensing Equipment | $100,000–$250,000 |
| 4-3-5. Unified Tire-Pavement Noise Model that Includes Texture and Absorptivity | $500,000–$1 million |
| Subtrack 4-4. Other Concrete Pavement Surface Characteristics | |
| 4-4-1. Splash and Spray Assessment Equipment | $1–$2 million |
| 4-4-2. Rolling Resistance Assessment Equipment | $1–$2 million |
| 4-4-3. Reflectivity/Illuminance Assessment Equipment | $1–$2 million |
| 4-4-4. Tire and Vehicle Wear Assessment Equipment | $1–$2 million |
| Subtrack 4-5. Integration of Concrete Pavement Surface Characteristics | |
| 4-5-1. Comprehensive Concrete Pavement Surface Characteristics Field Study | $500,000–$1 million |
| 4-5-2. Time Stability Evaluations of Concrete Pavement Surface Characteristics | $500,000–$1 million |
| 4-5-3. Unified Model for Concrete Pavement Texture, Friction, Noise, and Smoothness | $500,000–$1 million |
| 4-5-4. Concrete Pavement Mix Design System Integration Stage 4: Functionally Based Mix Design | $500,000–$1 million |
| 4-5-5. Relating Pavement Surface Characteristics to Vehicle Accidents | $1–$2 million |
| Subtrack 4-6. Evaluation of Products for Concrete Pavement Surface Characteristics | |
| 4-6-1. Pervious Concrete and Related Issues | $1–$2 million |
| 4-6-2. Exposed Aggregate Surfaces | $250,000–$500,000 |
| 4-6-3. Engineered/Optimized Wet Concrete Texturing | $1–$2 million |
| 4-6-4. Engineered/Optimized Hardened Concrete Grinding and Grooving | $1–$2 million |
| 4-6-5. Precast Pavement Surfaces | $250,000–$500,000 |
| Subtrack 4-7. Concrete Pavement Surface Characteristics Implementation | |
| 4-7-1. Workshops on Products to Improve Concrete Pavement Surface Characteristics | $1–$2 million |
| 4-7-2. Workshops on Measurement of Concrete Pavement Surface Characteristics | $1–$2 million |
| 4-7-3. Web-Based Training for Implementation of Research Products for Concrete Pavement Surface Characteristics | $500,000–$1 million |
| Total | $25.4–$54.25 million |
Track 4 problem statements are grouped into the following seven subtracks:
Each subtrack is introduced by a brief summary of the subtrack’s focus and a table listing the titles, estimated costs, products, and benefits of each problem statement in the subtrack. The problem statements follow.
This subtrack focuses on issues related to texture and friction properties of concrete pavements. Table 19 provides an overview of this subtrack.
| Problem Statement | Estimated Cost | Products | Benefits |
| 4-1-1. High-Speed Three-Dimensional Macrotexture Assessment Equipment | $2–$5 million | Advanced and effective high-speed 3D macrotexture assessment equipment with standards and specifications for its use. | Technology that can be a key component in assessing concrete pavement macrotexture in 3D and improved prediction of wet pavement friction. |
| 4-1-2. In Situ Three-Dimensional Microtexture Assessment Equipment | $500,000– $1 million |
Advanced and effective in situ 3D microtexture assessment equipment with standards and specifications for its use. | Automated method for measuring concrete pavement microtexture in situ. |
| 4-1-3. High-Speed Three-Dimensional Microtexture Assessment Equipment | $2–$5 million | Advanced and effective high-speed 3D microtexture assessment equipment with standards and specifications for its use. | High-speed laser equipment that can measure concrete pavement microtexture at highway speeds. |
| 4-1-4. Behind-the-Paver Texture-Sensing Equipment | $250,000–$500,000 | Advanced and effective behind-the-paver texture sensing equipment with standards and specifications for its use. | Technology that can be a key component for measuring concrete pavement texture behind the paver and minimized instances of over- and under-texturing. |
| 4-1-5. Multidimensional Concrete Pavement Friction Assessment | $1–$2 million | Effective methods for multidimensional friction assessment with their respective standards and specifications. | Advancements in concrete pavement friction assessment that use multidimensional models. |
| 4-1-6. Unified Concrete Pavement Texture and Friction Model | $500,000– $1 million |
A model that relates and integrates texture and friction characterization. | A model that advances the process of texture selection as it relates to friction, allowing improved prediction of friction resulting from texturing methods. |
Measuring pavement macrotexture has been a common practice in Europe for many years. In the United States, the important role of pavement macrotexture in providing adequate surface friction is being increasingly recognized. The mean profile depth (MPD) parameter describes macrotexture, and it can be used to predict wet pavement friction. One way of measuring MPD and other relevant texture metrics is to use high-speed vehicle-mounted laser-based measuring devices. The research in this problem statement will build off this technology to develop effective and high-speed macrotexture assessment equipment that can scan a pavement surface in 3D, giving a picture of both longitudinal and transverse variation in macrotexture.
The tasks include the following:
Benefits: Technology that can be a key component in assessing concrete pavement macrotexture in 3D and improved prediction of wet pavement friction.
Products: Advanced and effective high-speed 3D macrotexture assessment equipment with standards and specifications for its use.
Implementation: The research in this problem statement will be coordinated closely with research done under problem statement 4-2-1.
Microtexture refers to fine-scale pavement roughness (much finer than macrotexture) largely determined by the fine aggregate in concrete mortar. Concrete pavement microtexture is commonly measured in the laboratory or estimated in the field using friction measurements. However, because of the fine resolution necessary, no automated method for measuring microtexture in situ exists, much less at highway speeds. The research in this problem statement will develop effective 3D microtexture assessment equipment that can be used in situ (static).
The tasks include the following:
Benefits: Automated method for measuring concrete pavement microtexture in situ.
Products: Advanced and effective in situ 3D microtexture assessment equipment with standards and specifications for its use.
Implementation: The technology identified in this problem statement can be a key component to assess concrete pavement microtexture in situ.
No automated method for measuring concrete pavement microtexture at highway speeds currently exists. However, high-speed 3D laser equipment is expected to be available for measuring macrotexture at highway speeds. This technology can be adapted and improved (i.e., by increasing laser and computer processing power) to measure concrete pavement microtexture similarly at highway speeds. The research in this problem statement will develop this effective high-speed 3D microtexture assessment equipment.
The tasks include the following:
Benefits: High-speed laser equipment that can measure concrete pavement microtexture at highway speeds.
Products: Advanced and effective high-speed 3D microtexture assessment equipment with standards and specifications for its use.
Implementation: The technology identified in this problem statement can be a key component in the high-speed assessment of concrete pavement microtexture.
Many techniques indicate texture in plastic concrete pavements. However, current techniques are methods-based. While the as-built texture is clearly important, texture is rarely verified due to a lack of testing equipment and expertise. Ideally, texture should be verified in situ and in real time as the paver (texturer) moves. Texture could thus be adjusted in real time, and over-or under-texturing could be minimized. The research in this problem statement will develop effective behind-the-paver equipment that measures concrete pavement texture during placement.
The tasks include the following:
Benefits: Technology that can be a key component for measuring concrete pavement texture behind the paver and minimized instances of over- and under-texturing.
Products: Advanced and effective behind-the-paver texture sensing equipment with standards and specifications for its use.
Implementation: The research in this problem statement will be coordinated closely with problem statement 3-2-10.
Roadway friction is a complex parameter. First, it is commonly assessed longitudinally along the direction of travel, which is essential for determining vehicle stopping distances. However, this assessment does not address situations in which vehicles slide sideways or diagonally into adjacent lanes, particularly while traversing horizontal curves. Furthermore, friction varies with the presence of water or other lubricating substances on the roadway. The research in this problem statement will capture these and other variables by developing a more effective method for assessing multidimensional friction.
The tasks include the following:
Benefits: Advancements in concrete pavement friction assessment that use multidimensional models.
Products: Effective methods for multidimensional friction assessment with their respective standards and specifications.
Implementation: The research in this problem statement will advance concrete pavement friction assessment.
Significant research demonstrates the sensitivity of friction to texture in various wavelength ranges and explains the fundamental mechanisms involved. However, little systematic information currently explains the sensitivity of friction to the specific dimensions of each type of texture, including directionality and variables such as aggregate size or channel width and depth. The research in this problem statement will develop a model to relate and integrate texture and friction.
The tasks include the following:
Benefits: A model that advances the process of texture selection as it relates to friction, allowing for improved prediction of friction resulting from texturing methods.
Products: A model that relates and integrates texture and friction characterization.
Implementation: The research will advance texture selection as it relates to friction.
This subtrack focuses on issues related to concrete pavement smoothness. Table 20 provides an overview of this subtrack.
| Problem Statement | Estimated Cost | Products | Benefits |
| 4-2-1. High-Speed, High-Resolution Three-Dimensional Pavement Profiling | $2–$5 million | Effective methods for high-speed high-resolution 3D pavement profiling and their respective standards and specifications. | Pavement profiling methods that advance concrete pavement structure profiling. |
| 4-2-2. Next Generation Concrete Pavement Smoothness Index Development and Specifications | $500,000– $1 million |
Recommended refinements to AASHTO provisional standards for pavement profiling and ride quality. | Methods and specifications that advance the construction and evaluation of pavement smoothness, enhancing ride quality for the traveling public. |
| 4-2-3. Behind-the-Paver Smoothness Sensing Equipment | $100,000–$250,000 | Advanced and effective behind-the-paver smoothness sensing equipment with standards and specifications for its use. | Behind-the-paver technology that serves as a key component in sensing pavement smoothness, providing real-time information that can correct paving operations immediately. |
| 4-2-4. Design and Construction Guidelines to Improve Concrete Pavement Smoothness | $500,000– $1 million |
Comprehensive and accurate guidelines in design and construction that help stakeholders improve concrete pavement smoothness. | Guidelines that advance design and construction practices to achieve smooth concrete pavements. |
Current concrete pavement profiling technology commonly differentiates two categories of profiles: lateral and longitudinal. Lateral profiles allow for an assessment of rutting (e.g., from studded tire damage), superelevation of the road design, and other damage. Longitudinal profiles are more commonly analyzed, and they illustrate concrete pavement roughness and some forms of texture. While combining these two profiles can be beneficial, such combinations are rare because it is laborious, and the resulting complete profile is often questionable. Ideal concrete pavement profiles would include methods for 3D measurement, which allow pavement distresses and directional features in the pavement surface to be detected and quantified readily. The research in this problem statement will develop effective methods for high-speed, high-resolution 3D pavement profiling.
The tasks include the following:
Benefits: Pavement profiling methods that advance concrete pavement structure profiling.
Products: Effective methods for high-speed, high-resolution 3D pavement profiling and their respective standards and specifications.
Implementation: The research in this problem statement will be coordinated closely with problem statement 4-1-1.
There are four AASHTO standards for assessing concrete pavement smoothness. These standards provide an excellent resource for implementing a smoothness QA program, but they must be reviewed and revised continuously as more is learned about pavement smoothness measurement and interpretation. Research is needed in various aspects of pavement smoothness to ensure that these specifications continue to provide smooth pavements. The research in this problem statement will aim to refine the AASHTO standards based on the results of research and development efforts currently underway and conducted under this and other research programs.
The tasks include the following:
Benefits: Methods and specifications that advance the construction and evaluation of pavement smoothness, ultimately enhancing ride quality for the traveling public.
Products: Recommended refinements to AASHTO standards for pavement profiling and ride quality.
Implementation: The research in this problem statement will refine AASHTO standards for assessing concrete pavement smoothness, thus advancing the construction and evaluation of concrete pavements.
Concrete pavement smoothness is usually assessed after the pavement has gained enough strength for pavement profilers to traverse the surface without damage. In this scenario, a pavement that does not meet the minimum required smoothness level would require costly remedial methods, or worse, rejection of the pavement. The frequency of these consequential actions can be minimized if pavement smoothness is assessed during paving. The smoothness level would be reported to interested parties while the concrete is still plastic. The research in this problem statement will develop effective and advanced behind-the-paver smoothness sensing equipment that can assess pavement smoothness during paving.
The tasks include the following:
Benefits: Behind-the-paver technology that is a key component in sensing pavement smoothness, providing real-time information that can correct paving operations immediately.
Products: Advanced and effective behind-the-paver smoothness sensing equipment with standards and specifications for its use.
Implementation: The research in this problem statement will be coordinated closely with problem statement 3-2-9.
Strong evidence supports the hypothesis that pavements that are smooth when built remain smooth longer than pavements that are initially rough. To provide smooth pavements, most State highway agencies have implemented smoothness specifications that offer incentives for very smooth pavements and impose penalties for unacceptably rough pavements. However, little specific guidance helps contractors improve smoothness during pavement construction. Similarly, little guidance is provided to pavement designers to achieve smoothness goals. The research in this problem statement will develop such guidance, synthesizing ongoing work in this area.
The tasks include the following:
Benefits: Guidelines that advance design and construction practices to achieve smooth concrete pavements.
Products: Comprehensive and accurate guidelines in design and construction that help stakeholders improve concrete pavement smoothness.
Implementation: The research in this problem statement will result in guidelines for achieving pavement smoothness goals.
This subtrack focuses on issues related to tire-pavement noise generation, propagation, and mitigation related to concrete pavements. Table 21 provides an overview of this subtrack.
| Problem Statement | Estimated Cost | Products | Benefits |
| 4-3-1. Standardized Tire-Pavement Noise Measurement | $1–$2 million | A standardized method or combination of methods for measuring tire-pavement noise. | Methods that advance the industry by allowing for a comparison of tire-pavement noise measurements made using different testing methods. |
| 4-3-2. Standardized Vehicle Interior Noise Measurement | $250,000–$500,000 | A standardized method for measuring interior vehicle noise. | A method that advances procedures for measuring vehicle interior noise, improving decisions about the influence of tire-pavement noise on the traveling public. |
| 4-3-3. Tire-Pavement Noise Thresholds | $500,000– $1 million |
A report defining tire-pavement noise thresholds that can be used to optimize concrete pavement surface characteristics. | Identified thresholds that advance the concrete pavement industry by providing rational methods for designing and constructing concrete pavements with acceptable friction and tire-pavement noise characteristics. |
| 4-3-4. Behind-the-Paver Noise Sensing Equipment | $100,000–$250,000 | Advanced and effective equipment to measure concrete pavement noise and related surface characteristics behind the paver, as well as standards and specifications for using the equipment. | Technology that serves as a key component in sensing concrete pavement noise and surface texture behind the paver. |
| 4-3-5. Unified Tire-Pavement Noise Model that Includes Texture and Absorptivity | $500,000– $1 million |
A sophisticated model for predicting tire-pavement noise as a function of concrete pavement texture and other physical properties. | Models that predict tire-pavement noise as a function of its relationship to texture, materials characteristics, and other pavement features, as well as a rational approach to predicting tire-pavement noise. |
Several methods currently measure both vehicle and tire-pavement noise. Traditionally, traffic noise is measured using wayside measures, such as statistical pass-by testing, which samples passing vehicles at the roadside and classifies their noise emission by the type of vehicle. Another wayside method, controlled pass by, uses a known (test) vehicle with known tire properties that passes a fixed microphone. This method allows a detailed assessment of noise generation because many of the dependent variables are known or controlled. In recent years, wayside testing has been standardized by AASHTO as both a statistical isolated pass-by (SIP) method and the continuous-flow traffic time integrated method (CTIM).
In recent years, an alternative classification of noise measurement has become more common. Close proximity methods, such as on-board sound intensity (OBSI), have been standardized by AASHTO. In this type of testing, microphones are mounted to a test vehicle near the tire-pavement contact patch. These methods seek to isolate the noise generated at the contact patch from other sources.
Because these two measurements are uniquely different, comparisons can be difficult. The research in this problem statement will improve the standardized methods for measuring and comparing tire-pavement noise.
The tasks include the following:
Benefits: Improved methods that advance the industry by allowing for a comparison of tire-pavement noise measurements made using different testing methods.
Products: A standardized method or combination of methods for measuring tire-pavement noise.
Implementation: The research in this problem statement will develop improved standardized methods for measuring tire-pavement noise.
Recent research has found that objectionable vehicle interior noise is identified with tonal quality (specific frequencies) more than total noise level. This objectionable tonal quality primarily results from spikes in sound pressures at discrete frequencies, commonly generated by repeating patterns in pavement texture, such as transverse tining or even low frequency chatter. To better understand these phenomena, standardized interior noise evaluation procedures are required. Previous research revealed that subjective noise ratings of subjects in test vehicles on different surface textures do not correspond with the objective total noise measurements taken outside the vehicle. Therefore, to further explore these gaps, the research in this problem statement will develop a standardized method for measuring vehicle interior noise.
The tasks include the following:
Benefits: A method that advances procedures for measuring vehicle interior noise, allowing improved decisions about the influence of tire-pavement noise on the traveling public.
Products: A standardized method for measuring interior vehicle noise.
Implementation: The results of this research will advance methods for measuring vehicle interior noise, allowing more informed decisions about the impact of vehicle interior noise on the traveling public.
Altering certain concrete pavement surface characteristics (i.e., increasing macrotexture for improved friction or reduced splash and spray) can sometimes worsen tire-pavement noise. While safety is more important than driver comfort or reduced noise, noise thresholds should be a factor in pavement optimization, just as are friction thresholds. These noise thresholds should characterize tire-pavement noise levels and frequencies, scaling them to include a range of human responses from mere annoyance to driver and abutter distraction.
The research in this problem statement will define these threshold values so that more informed decisions can be made about the tradeoffs between tire-pavement noise and other pavement surface characteristics.
The tasks include the following:
Benefits: Identified thresholds that advance the concrete pavement industry by providing rational methods for designing and constructing concrete pavements with acceptable friction and tire-pavement noise characteristics.
Products: A report defining tire-pavement noise thresholds that can be used to optimize concrete pavement surface characteristics.
Implementation: The results of this research will be to identify tire-pavement noise thresholds that provide more rational methods to optimize concrete pavement surface characteristics.
The noise generated by tire-pavement contact is related to the surface texture and other concrete pavement surface properties, particularly on the wearing course. However, current technology only allows tire-pavement noise levels to be assessed after the pavement has hardened sufficiently to accommodate a test vehicle. If tire-pavement noise is a specification value and if this value falls outside an acceptable level, costly methods could be required to mitigate the problem. However, if tire-pavement noise, pavement surface texture, and other properties (e.g., absorptivity) related to tire-pavement noise could be assessed during placement, improvements could be made in real time while the concrete is still plastic. The research in this problem statement will identify and tentatively develop effective and advanced behind-the-paver noise sensing equipment.
The tasks include the following:
Benefits: Technology that serves as a key component in sensing concrete pavement noise and surface texture behind the paver.
Products: Advanced and effective equipment to measure concrete pavement noise and related surface characteristics behind the paver, as well as standards and specifications forusing the equipment.
Implementation: The research in this problem statement will be coordinated closely with problem statement 3-2-11.
A relationship clearly exists between concrete pavement surface texture and the noise generated by the tire-pavement interface. Furthermore, various concrete pavement properties, including absorptivity, stiffness, and density, affect tire-pavement noise levels. Currently, information about the relationships between tire-pavement noise and physical pavement characteristics is empirical at best. However, models must contain numerous levels of complexity because tire characteristics are equally as important and complex. The research in this problem statement will identify and/or develop improved models to predict the tire-pavement noise for a variety of concrete pavement surfaces. The unified model should consider various types of directional texturing, as well as more random textures that may result from advancements in texturing technology.
The tasks include the following:
Benefits: Models that predict tire-pavement noise as a function of its relationship to texture, materials characteristics, and other pavement features, as well as a rational approach to predicting tire-pavement noise.
Products: A sophisticated model for predicting tire-pavement noise as a function of concrete pavement texture and other physical properties.
Implementation: This research will develop a model that supplements numerous tasks that require a better understanding of the relationship between texture, materials characteristics, and tire-pavement noise. For example, concrete mix design procedures that attempt to produce low-noise pavements will require this model.
This subtrack focuses on issues related to other surface characteristics with respect to concrete pavements. Table 22 provides an overview of this subtrack.
| Problem Statement | Estimated Cost | Products | Benefits |
| 4-4-1. Splash and Spray Assessment Equipment | $1–$2 million | Effective and advanced splash and spray assessment equipment with specifications for its use. | Equipment that assesses the relationship between macrotexture and splash and spray, improving safe driving conditions. |
| 4-4-2. Rolling Resistance Assessment Equipment | $1–$2 million | Advanced and effective rolling resistance assessment equipment with standards and specifications for its use. | Equipment that directly measures rolling resistance and methods to reduce this resistance, which increases user costs through increased fuel consumption and vehicle wear. |
| 4-4-3. Reflectivity/ Illuminance Assessment Equipment | $1–$2 million | Advanced and effective reflectivity/illuminance assessment equipment. | Equipment that assesses concrete pavement reflectivity/illuminance to optimize the level of reflectivity/illuminance and improved ride safety during daylight hours. |
| 4-4-4. Tire and Vehicle Wear Assessment Equipment | $1–$2 million | Advanced and effective tire and vehicle wear assessment equipment. |
Equipment that directly assesses tire and vehicle wear and a better understood relationship between texture, tire, and vehicle wear. |
Tires rolling on a pavement with standing water commonly produce splash and spray, which occurs when the vehicle tires on the pavement surface attract water and eject it as small droplets into the air. The airborne water can reduce visibility, particularly for vehicles traveling next to or closely behind other vehicles. Research suggests that 10 percent of wet weather accidents are caused by poor visibility due to splash and spray. While macrotexture is a primary contributor to splash and spray, little is known about the quantitative relationship between macrotexture and splash and spray. The research in this problem statement will develop effective splash and spray assessment equipment. This equipment will allow the relationship between surface texture and splash and spray to be better understood. Furthermore, this test procedure may be used to measure the effectiveness of a given pavement in meeting reasonable splash and spray limits, thus increasing safety.
The tasks include the following:
Benefits: Equipment that assesses the relationship between macrotexture and splash and spray, improving safe driving conditions.
Products: Effective and advanced splash and spray assessment equipment with specifications
for its use.
Implementation: The technology developed in this problem statement will be a key component in assessing splash and spray and improving safety.
Megatexture and concrete pavement roughness characteristics contribute to rolling resistance. Excessive rolling resistance can cause vehicles to work harder, increasing user costs through increased fuel consumption and vehicle wear. The research in this problem statement will develop effective rolling resistance assessment equipment, allowing the effects of rolling resistance to be measured directly. This equipment will also improve understanding of the relationship between this surface characteristic, texture, and other physical concrete pavement properties.
The tasks include the following:
Benefits: Equipment that directly measures rolling resistance and methods to reduce this resistance, which increases user costs through increased fuel consumption and vehicle wear.
Products: Advanced and effective rolling resistance assessment equipment with standards and specifications for its use.
Implementation: The technology developed in this problem statement will be a key component in assessing rolling resistance.
Different concrete pavement materials and textures can affect reflectivity/illuminance characteristics. Some reflectivity/illuminance can be beneficial (e.g., reflection that aids nighttime driving), but too much can be distracting (e.g., sunlight reflected during daylight hours, particularly at dawn or dusk). The research in this problem statement will develop effective reflectivity/illuminance assessment equipment. This equipment will allow optimum materials and textures to be selected to provide the ideal level of reflectivity/illuminance.
The tasks include the following:
Benefits: Equipment that assesses concrete pavement reflectivity/illuminance, allowing the level of reflectivity/illuminance to be optimized, and improved ride safety during daylight hours.
Products: Advanced and effective reflectivity/illuminance assessment equipment.
Implementation: The technology developed in this problem statement will be a key component in assessing concrete pavement reflectivity/illuminance.
Tire and vehicle wear relate directly to user costs. Microtexture is a primary factor that contributes to tire wear. Megatexture and roughness contribute to rolling resistance, which contributes to vehicle wear. The research in this problem statement will develop effective tire and vehicle wear assessment equipment. This equipment will improve understanding of the relationship between texture and vehicle and tire wear.
The tasks include the following:
Benefits: Equipment that directly assesses tire and vehicle wear as well as a better understood relationship between texture and tire and vehicle wear.
Products: Advanced and effective tire and vehicle wear assessment equipment.
Implementation: The technology developed in this problem statement will be a key component in assessing tire and vehicle wear.
This subtrack focuses integrating the various surface characteristics for concrete pavements. Table 23 provides an overview of this subtrack.
| Problem Statement | Estimated Cost | Products | Benefits |
| 4-5-1. Comprehensive Concrete Pavement Surface Characteristics Field Study | $500,000– $1 million |
A structured database and numerous supporting reports and case studies that define optimum concrete pavement surface characteristics and the methods for achieving them. | Concrete pavement surface characteristics guidance that supplements research in this and other tracks and improved understanding of optimum concrete pavement surface characteristics. |
| 4-5-2. Time Stability Evaluations of Concrete Pavement Surface Characteristics | $500,000– $1 million |
Reports defining effective surfacing methods that provide durable surface characteristics. | Guidance that documents the longevity and durability of various concrete pavement surface characteristics and surfacing methods that result in more durable surface characteristics. |
| 4-5-3. Unified Model for Concrete Pavement Texture, Friction, Noise, and Smoothness | $500,000– $1 million |
A model that unifies texture, friction, noise, smoothness, and other related variables. | Models that consider concrete pavement texture, friction, noise, smoothness, and other related variables to define optimal texture. |
| 4-5-4. Concrete Pavement Mix Design System Integration Stage 4: Functionally Based Mix Design | $500,000– $1 million |
A mix design system that accounts for the functional demands of the pavement surface layer. | Improved mix design techniques that will rationally meet pavement functional requirements, such as noise, ride quality, and texture. |
| 4-5-5. Relating Pavement Surface Characteristics to Vehicle Accidents | $1–$2 million | Reports detailing a methodical evaluation of vehicle accident risks as a function of the types and magnitudes of pavement surface characteristics. | Improved understanding of the relationship between pavement surface characteristics and vehicle accidents and improved methods for designing and constructing concrete pavements to minimize accident rates. |
Researching designs, construction records, and past performance reports is often not enough to understand the advantages or disadvantages of certain concrete surface pavement characteristics. Therefore, performing a field study is necessary. The research in this problem statement will perform a comprehensive field study of pavement surface characteristics to define the surface characteristics that maximize friction and smoothness while minimizing noise. Similarly, additional characteristics may be investigated as needed.
The tasks include the following:
Benefits: Concrete pavement surface characteristics guidance that supplements research in this and other tracks and improved understanding of optimum concrete pavement surface characteristics.
Products: A structured database and numerous supporting reports and case studies that define optimum concrete pavement surface characteristics and the methods for achieving them.
Implementation: The data, reports, and case studies produced under this problem statement will advance the concrete paving industry toward the goal of achieving optimum concrete pavement surface characteristics.
Selecting texturing characteristics that maximize surface friction and smoothness while minimizing noise is undeniably important for optimizing concrete pavement performance. However, the longevity of these characteristics and the durability of the pavement itself must also be considered. The research in this problem statement will evaluate the time stability of certain pavement surface characteristics and the impacts that various surfacing methods might have on durability.
The tasks include the following:
Benefits: Guidance that documents the longevity and durability of various concrete pavement surface characteristics and surfacing methods that result in more durable surface characteristics.
Products: Reports defining effective surfacing methods that provide durable
surface characteristics.
Implementation: The reports written in this problem statement will help develop improved methods for designing and constructing more durable concrete pavement surfaces. This research will be coordinated closely with the experiments conducted under problem statement 4-5-1.
Concrete pavement texture, friction, noise, and smoothness are all related and can therefore be related through modeling. Empirical evidence shows that certain types of texture that provide good friction will increase noise and decrease smoothness. Because ideal as-built texture provides good friction while minimizing noise and maximizing smoothness, a more thorough understanding of the relationships between texture, friction, noise, and smoothness is necessary. The research in this problem statement will develop a comprehensive model that integrates texture, friction, noise, and smoothness to define optimal texture. This model should consider numerous other variables, including pavement materials properties and tire properties.
The tasks include the following:
Benefits: Models that consider concrete pavement texture, friction, noise, smoothness, and other related variables to define optimal texture.
Products: A model that unifies texture, friction, noise, smoothness, and other related variables.
Implementation: This research will develop a model that will allow the industry to relate the complex nature of concrete pavement texture to the various pavement surface characteristics.
Concrete pavement and materials engineering decisions often are driven by functional requirements established at the highest levels. These requirements commonly respond to a perceived public need, such as driver and abutter demands for quieter, smoother, and safer pavements. While concrete pavements can meet these functional demands, pavements must be designed appropriately to do so. The research in this problem statement will be used to develop a concrete mix design system that will evaluate the effects of concrete materials and mixture on pavement functional requirements (i.e., noise, ride quality, and texture). With a better understanding of the relationships between concrete materials and mixtures and pavement functional requirements, improved mix design techniques can be developed to meet these functional requirements more rationally. These mix design procedures will allow innovative solutions, such as two-lift pavements, to be designed optimally for a given set of functional demands.
The tasks include the following:
Benefits: Improved mix design techniques that will rationally meet pavement functional requirements such as noise, ride quality, and texture.
Products: A mix design system that accounts for the functional demands of the pavement surface layer.
Implementation: The research in this problem statement will develop a mix design system that sufficiently addresses the functional demands of the user.
Because safety is important, the highway community must design and build roads that minimize the acceptable risks of vehicular accidents. Pavement surface characteristics, including texture, friction, splash and spray, illuminance, and reflectivity, can impact accident potential. However, little is known about the relationship between pavement surface characteristics and the increased accident rate. Because numerous variables impact the overall accident rate, quantifying the accident risks from any single factor is difficult. Compounding this difficulty are the potential liability issues involved with studies of this nature. As a result, this research must reasonably ensure that its results will not damage the highway industry. The research in this problem statement should methodically evaluate numerous existing concrete pavements, assessing the relevant pavement surface characteristics and collecting accident rate statistics categorized by the likely contributors to the accidents.
The tasks include the following:
Benefits: Improved understanding of the relationship between pavement surface characteristics and vehicle accidents and improved methods for designing and constructing concrete pavements to minimize accident rates.
Products: Reports detailing a methodical evaluation of vehicle accident risks as a function of the types and magnitudes of pavement surface characteristics.
Implementation: The results of this research will help prioritize the measures needed to improve design and construction practices. Furthermore, optimizing concrete pavement surfaces requires that the risks of accidents derived in this optimization effort be understood.
This subtrack includes an evaluation of various concrete paving solutions in improving surface characteristics. Table 24 provides an overview of this subtrack.
| Problem Statement | Estimated Cost | Products | Benefits |
| 4-6-1. Pervious Concrete and Related Issues | $1–$2 million | Guidelines and specifications for the design and construction of porous concrete surfaces. | Effective methods that will lead to the design, construction, and maintenance of high-quality porous concrete pavement surfaces. |
| 4-6-2. Exposed Aggregate Surfaces | $250,000–$500,000 | Guidelines and specifications for designing and constructing exposed aggregate concrete pavement surfaces. | Effective methods for designing and constructing exposed aggregate concrete pavement surfaces as well as exposed aggregate concrete pavement surfaces with low noise, excellent high-speed skidding resistance, good surface durability, and low splash and spray. |
| 4-6-3. Engineered/ Optimized Wet Concrete Texturing |
$1–$2 million | Guidelines and specifications for designing and constructing conventionally textured concrete pavement surfaces. | Optimized conventional methods for texturing concrete pavement surfaces that maximize surface friction while minimizing tire-pavement noise. |
| 4-6-4. Engineered/ Optimized Hardened Concrete Grinding and Grooving | $1–$2 million | Guidelines and specifications for designing, constructing, and grinding concrete pavement surfaces. | Effective grinding and grooving methods that maximize surface friction while minimizing tire-pavement noise and improving macrotexture and microtexture. |
| 4-6-5. Precast Pavement Surfaces | $250,000–$500,000 | Guidelines and specifications for designing and constructing precast concrete pavement solutions. | Methods for designing and constructing precast concrete pavement surfaces with optimum surface characteristics and optimized surface characteristics that are constructed as designed with minimized variations due to construction conditions. |
Pervious concrete pavement has demonstrated an ability to provide surface characteristics similar to those associated with open-graded (porous) asphalt pavements. However, the pervious concrete pavement only performs well if the surface is well maintained. As with porous asphalt surfaces, the pervious concrete pavement surface must be cleaned regularly to prevent debris from clogging the pores that give the surface its beneficial drainage and acoustic properties. Additionally, initial experiences with pervious concrete pavement in Belgium showed poor durability in freezing weather; however, these mixtures since have been made more durable by adding polymers and other cement contents. The research in this problem statement will further develop effective methods for designing and constructing pervious concrete surfaces.
The tasks include the following:
Benefits: Effective methods that will lead to the design, construction, and maintenance of high-quality pervious concrete pavement surfaces.
Products: Guidelines and specifications for the design and construction of pervious concrete surfaces.
Implementation: The guidelines and specifications developed in this problem statement will improve design and construction of pervious concrete pavement surfaces.
Though widely used in European countries, the exposed aggregate technique has not been widely used in the United States. One reason for this is that an experimental U.S. project on I-75 in Detroit, MI, did not show the improved surface friction and tire-pavement noise that had been expected. However, the European experience and subsequent U.S. experiences (e.g., I-70 in Kansas) with the exposed aggregate technique illustrates that, when properly designed and constructed, exposed aggregate surfaces perform very well. Characteristics improved in exposed aggregate pavements include low noise, excellent high-speed skidding resistance, good surface durability, and low splash and spray. The research in this problem statement will further develop effective methods for designing and constructing exposed aggregate concrete pavement surfaces.
The tasks include the following:
Benefits: Effective methods for designing and constructing exposed aggregate concrete pavement surfaces and exposed aggregate concrete pavement surfaces with low noise, excellent high-speed skidding resistance, good surface durability, and low splash and spray.
Products: Guidelines and specifications for designing and constructing exposed aggregate concrete pavement surfaces.
Implementation: The guidelines and specifications developed in this problem statement will improve the design and construction of exposed aggregate concrete pavement surfaces. This research will be coordinated closely with problem statement 5-2-4.
The importance of concrete pavement surface texture characteristics for roadway safety has been recognized since the late 1940s when increases in traffic volumes and vehicle speeds resulted in increased wet weather accidents and fatalities. Often, appropriate microtexture is sufficient to provide adequate stopping on a concrete pavement when vehicles are traveling slower than 50 mi/h. However, when higher vehicle speeds are expected, improved microtexture and macrotexture is necessary to provide adequate wet-pavement friction. While increasing macrotexture reduces splash and spray, rougher macrotexture also increases tire-pavement noise. Similarly, increasing microtexture increases tire wear, although often insignificantly. The research in this problem statement will refine the conventional texturing methods frequently used today, including tining and drag methods used on fresh concrete pavement surfaces. These texturing methods will be engineered to maximize surface friction and minimize tire-pavement noise.
The tasks include the following:
Benefits: Optimized conventional methods for texturing concrete pavement surfaces, maximizing surface friction while minimizing tire-pavement noise.
Products: Guidelines and specifications for designing and constructing conventionally textured concrete pavement surfaces.
Implementation: The guidelines and specifications developed in this problem statement will improve the design and construction of conventionally textured concrete pavement surfaces.
Grinding both newly placed and existing concrete pavements effectively improves surface friction and smoothness while decreasing tire-pavement noise. Grinding improves pavement frictional characteristics by exposing microtexture and creating macrotexture. Additionally, it increases lateral control for vehicles, especially on transitions and superelevated curve sections. The research in this problem statement will develop effective grinding and grooving methods that will maximize surface friction and minimize tire-pavement noise.
The tasks include the following:
Benefits: Effective grinding and grooving methods that maximize surface friction while minimizing tire-pavement noise, improving macrotexture and microtexture.
Products: Guidelines and specifications for designing, constructing, and grinding concrete pavement surfaces.
Implementation: The guidelines and specifications developed in this problem statement will improve the design, construction, and grinding of concrete pavement surfaces.
Concrete pavements designed with optimized surface characteristics may not be constructed as designed due to many factors, including contractor inexperience or environmental conditions during construction. Using precast concrete pavement surfaces will minimize these construction variables because construction processes can be more controlled. The research in this problem statement will develop guidelines and specifications for designing and constructing precast concrete pavement surfaces with optimum surface characteristics. Precast surfaces with innovative features, such as Helmholtz resonators, have already been implemented in Europe. These precast surface technologies also should be attempted in the United States.
The tasks include the following:
Benefits: Methods for designing and constructing precast concrete pavement surfaces with optimum surface characteristics and optimized surface characteristics that are constructed as designed with minimized variations due to construction conditions.
Products: Guidelines and specifications for designing and constructing precast concrete pavement solutions.
Implementation: The guidelines and specifications developed in this problem statement will improve the design and construction of precast concrete pavements. This research will be coordinated closely with problem statement 8-2-5.
This subtrack includes implementation activities related to concrete pavement surface characteristics. Table 25 provides an overview of this subtrack.
| Problem Statement | Estimated Cost | Products | Benefits |
| 4-7-1. Workshops on Products to Improve Concrete Pavement Surface Characteristics | $1–$2 million | Workshops and conferences on products for improving concrete pavement surface characteristics. | Technology transfer opportunities for products that improve concrete pavement surface characteristics. |
| 4-7-2. Workshops on Measurement of Concrete Pavement Surface Characteristics | $1–$2 million | Workshops and conferences on methods and equipment for measuring concrete pavement surface characteristics. | Technology transfer opportunities for methods and equipment that measure concrete pavement surface characteristics. |
| 4-7-3. Web-Based Training for Implementation of Research Products for Concrete Pavement Surface Characteristics | $500,000– $1 million |
A Web site that hosts Web-based modules that train contractors, designers, and owner-agencies in software and equipment on concrete pavement surface characteristics. | Web-based training modules that allow contractors, designers, and owner-agencies to access recent research on concrete pavement surface characteristics and technology transfer accessible from any computer with Internet access. |
While new products for improving concrete pavement surface characteristics constantly are being developed, transportation agencies often are slow to adopt them because they are unfamiliar with the new technologies and lack research resources. Workshops provide an ideal environment for familiarizing and training agencies in new products for improving concrete pavement surface characteristics. The workshops developed will provide technology transfer opportunities for products that improve concrete pavement surface characteristics.
The tasks include the following:
Benefits: Technology transfer opportunities for products that improve concrete pavement
surface characteristics.
Products: Workshops and conferences on products for improving concrete pavement
surface characteristics.
Implementation: This problem statement will result in numerous workshops and conferences on products for improving concrete pavement surface characteristics at various venues throughout the United States, advancing concrete pavement surface design, construction, and evaluation.
While new methods and equipment for measuring concrete pavement surface characteristics are constantly being developed, transportation agencies are often slow to adopt them because they are unfamiliar with these new technologies and lack research resources. Workshops provide an ideal environment for familiarizing and training agencies in new methods and equipment for measuring concrete pavement surface characteristics. The workshops developed will provide technology transfer of methods and equipment for measuring concrete pavement surface characteristics.
The tasks include the following:
Benefits: Technology transfer opportunities for methods and equipment that measure concrete pavement surface characteristics.
Products: Workshops and conferences on methods and equipment for measuring concrete pavement surface characteristics.
Implementation: This problem statement will result in numerous workshops and conferences on methods and equipment for measuring concrete pavement surface characteristics, advancing concrete pavement surface design, construction, and evaluation.
Although every year new research products and technologies are developed and ready for implementation, transportation agencies often implement and use the new research inadequately. Workshops offer contractors and owner-agencies the opportunity to learn about new research products and technologies, but agencies often cannot afford to send employees to workshops or may be restricted from traveling to a workshop outside their home State. Fortunately, with Web-based training, contractors, designers, and owner-agencies can explore new research products and technologies from any computer with Internet access. On-demand Web-based training can include case studies, online software applications, documentation, and other resources to make recent research on concrete pavement surface characteristics accessible to the concrete paving community.
The tasks include the following:
Benefits: Web-based training modules that allow contractors, designers, and owner-agencies to access recent research on concrete pavement surface characteristics and technology transfer accessible from any computer with Internet access.
Products: A Web site that hosts Web-based modules that train contractors, designers, and owner-agencies in software and equipment on concrete pavement surface characteristics.
Implementation: The Web-based training modules developed in this problem statement will allow widely accessible technology transfer to implement new research products for concrete pavement surface characteristics.
