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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
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    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Incorporating Network-Level Friction Data into KYTC's Pavement Resurfacing Prioritization</title>
      <link>https://rip.trb.org/View/2244515</link>
      <description><![CDATA[Kentucky Transportation Cabinet (KYTC) identifies and prioritizes pavement resurfacing projects based on available friction data, but few pavements undergo friction testing. Historically, friction data have only been available through either the Cabinet’s polish-resistant aggregate certification process or at specific locations for which reviews have been requested. With KYTC’s network-level SCRIM testing, the agency can analyze relationships between friction properties, roadway geometry, and crash data. Using these data, pavement management staff can factor existing friction properties into the project prioritization process. But methods are still needed to incorporate friction properties into KYTC’s existing pavement evaluation process to improve safety on state-maintained roadways.]]></description>
      <pubDate>Thu, 14 Sep 2023 08:49:31 GMT</pubDate>
      <guid>https://rip.trb.org/View/2244515</guid>
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      <title>RES2024-08: Evaluation and Development of Cost Prediction Models for Resurfacing Projects to Improve M &amp; R Analysis and Project Development</title>
      <link>https://rip.trb.org/View/2233700</link>
      <description><![CDATA[Tennessee Department of Transportation (TDOT) needs a methodology and tool to accurately predict costs of resurfacing projects during the project development and M&R analysis that will aid TDOT engineers in selecting the best pavement resurfacing treatment type, prioritizing resurfacing project, and developing project bundling strategy that can increase the competition and decrease the project costs. The research will identify the best practices of predicting quick and accurate resurfacing projects costs, strategy for prioritizing projects, and bundle projects to secure more competitive bids. It will consist of an extensive review of existing literature on the topic. A TDOT-specific automation tool will be developed to predict resurfacing project costs to improve M&R analysis and project development. The tool will utilize historical data and machine learning models. Recommendation to integrate the new estimating tool into existing workflow and business practices will be provided. The findings of the study will be shared with TDOT as well as other interested state DOTs.]]></description>
      <pubDate>Fri, 25 Aug 2023 15:26:17 GMT</pubDate>
      <guid>https://rip.trb.org/View/2233700</guid>
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      <title>Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation Projects</title>
      <link>https://rip.trb.org/View/1867134</link>
      <description><![CDATA[NCHRP Report 876, Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects, presents a rational approach for estimating the cost-effectiveness of including safety and operational improvements in a resurfacing, restoration, or rehabilitation (3R) project. The approach uses the performance of the existing road in estimating the benefits and cost-effectiveness of proposed design improvements. These guidelines are intended to replace TRB Special Report 214, Designing Safer Roads: Practices for Resurfacing, Restoration, and Rehabilitation. The guidelines are accompanied by two spreadsheet tools, one for analyzing a single design alternative and one for comparing several alternatives or combinations of alternatives (available at the link above).
 
Prior to 1976, federal highway funds could only be used for the construction of new highways or the reconstruction of existing highways. The Federal-Aid Highway Act of 1976 allowed the use of federal aid for resurfacing, restoration, and rehabilitation (3R) projects on federal-aid highways. However, in 1976 there were no standards for 3R improvements. Transportation agencies relied on standards for new or reconstructed roadways in the AASHTO Policy on Geometric Design of Highways and Streets (the “Green Book”), and where the proposed geometric elements did not meet the AASHTO guidelines on a 3R project, design exceptions or exemptions had to be sought. In response to a provision in the Surface Transportation Assistance Act of 1982, the Secretary of Transportation requested the National Academy of Sciences (now the National Academies of Sciences, Engineering, and Medicine) to study the cost-effectiveness of geometric design standards and recommend minimum standards for 3R projects on existing federal-aid highways, except freeways. The purpose of 3R standards was two-fold: (1) to identify minimum standards for selective geometric elements for which 3R funding could be used to maintain existing highways in an effort to extend their service life and (2) to provide transportation agencies with the ability to make cost-effective improvements to existing highways for selective geometric elements to enhance safety and reduce crashes. The result of this study was TRB Special Report 214: Designing Safer Roads: Practices for Resurfacing, Restoration, and Rehabilitation published in 1987.
 
Since 1987, values for many of the design elements within the AASHTO Green Book have been revised, including FHWA’s designated 13 controlling criteria, and the cost of construction has changed. Incremental geometric design improvements in 3R projects can be cost effective and have significant payoffs in safety and operational benefits. Furthermore, with the publication of the AASHTO Highway Safety Manual and other recent publications, additional knowledge is available regarding the relationship of geometric elements to the frequency and severity of crashes.
 
In NCHRP Project 15-50, MRIGlobal reviewed the literature and state of the practice for designing 3R projects. They also reviewed the latest research on the safety impacts of design improvements and developed cost-benefit analysis equations for the most common design improvements applied to 3R projects. This was supported by the development of spreadsheet tools for evaluating alternative designs. The final research results reflect the experience of 6 state departments of transportation in applying the draft design guidelines and supporting materials. This occurred under NCHRP Project 15-50(01), “Implementation Assessment of 3R Design Guidelines.”]]></description>
      <pubDate>Mon, 19 Jul 2021 22:28:32 GMT</pubDate>
      <guid>https://rip.trb.org/View/1867134</guid>
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    <item>
      <title>Establishing Roadway Cross-Slopes During Resurfacing Projects</title>
      <link>https://rip.trb.org/View/1638640</link>
      <description><![CDATA[Many of Kentucky’s rural roads were built over existing wagon trails and paths. Unlike modern roadway design, which considers speed, geometry, and frictional forces to determine appropriate superelevations in horizontal curves, as well as rates of change, to provide a safer roadway and more comfortable driving experience, older roads were built with a typical 2% crown slope. The 2% crown slope continues through horizontal curves, which directs or pushes vehicles away from the direction of travel. Not only is this less than optimal for motorists, it often produces an uncomfortable feeling for drivers.]]></description>
      <pubDate>Wed, 17 Jul 2019 13:37:30 GMT</pubDate>
      <guid>https://rip.trb.org/View/1638640</guid>
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    <item>
      <title>Scientific Innovations in Micro-surfacing and Slurry Seal Mixture Design TR-755</title>
      <link>https://rip.trb.org/View/1549927</link>
      <description><![CDATA[In recent years, focus on pavement preservation implementation has been renewed as agencies face budget challenges and aging road infrastructure. Microsurfacing and slurry seals have shown great potential as fast, cost-effective pavement preservation and minor rehabilitation strategies. Microsurfacing and slurry seals can be used in high traffic areas and in areas with high traffic demands, which require rapid repairs and completion of work (Asphalt Institute 2008). A recent analysis completed by Iowa State University (ISU) researchers of Iowa Department of Transportation (DOT) data has shown that the application of microsurfacing and slurry seals are providing improvements to roadway characteristics; however, based on survey results sent to county engineers, guidance of pavement preservation is still needed. A large part of understanding microsurfacing and slurry seals is knowledge of the mixture design processes. In general, the understanding of design processes for emulsion-based mixtures needs to be improved so proper field adjustments can be made in real time. This proposal aims to improve and incorporate chemistry-based measurements for microsurfacing and slurry seals to provide a quantitative metric to formulate and tweak designs both in the lab and in the field.
This research project will provide seed funding to explore a scientific approach to microsurfacing mixture design using zeta potential. Zeta potential measurements are the electrical forces that influence particle stability, repulsion, and attraction in the microsurfacing/slurry seal mixture design. The zeta potential of an asphalt-water emulsion system is the measure of the potential difference between emulsifiers adsorbed on the surface of the asphalt droplets and the conducting liquid suspension (water). If mixture components could be engineered with zeta potential, the breaking and setting of the emulsion could be more precisely controlled and scientifically adjusted. The mixture components with more negative zeta potential are holding the mixture in suspension while the components with more positive zeta potential are inducing flocculation. The point at which these components work together to chemically break the emulsion in the mixture is called the isoelectric point.
The objective of this research is to investigate the use of zeta potential as a measurement to predict setting behavior and performance of micro-surfacing mixtures. Results and comparisons between mechanical testing, methylene blue values for aggregates, and zeta potential testing will be performed.
(1) Use zeta potential to incorporate scientific measurements into micro-surfacing mixture design.
(2) Research will provide recommendations about improving micro-surfacing/slurry seal materials.
(3) Research will investigate how zeta potential titrations can be used to better formulate a slurry/micro mixture for improved adhesion properties and/or a faster setting rate to quickly return traffic to a roadway.]]></description>
      <pubDate>Wed, 26 Sep 2018 14:54:03 GMT</pubDate>
      <guid>https://rip.trb.org/View/1549927</guid>
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      <title>The Effects of Public-Private Partnerships on Traffic Safety: Evidence from Mexico</title>
      <link>https://rip.trb.org/View/1264495</link>
      <description><![CDATA[The United States is facing severe infrastructure financing problems. Revenues from fossil-fuel based taxes are declining as vehicles become more fuel efficient and as annual vehicle miles traveled declines. Many states and localities are increasing the role of private investors through public-private partnerships (PPP), and 31 states have now passed PPP enabling legislation. These concerns are particularly salient in the Northeastern part of the United States. Meanwhile, traffic safety, although improving, remains a critical concern in all regions. This study will combine these two areas of inquiry by examining the effects of private participation on traffic safety. The project will use a novel data set from Mexico, which has extensive PPP experience. The data set includes approximately 800 Mexican municipalities from 1997 to 2010, resulting in a panel of about 11,000 observations. The project can identify government versus PPP control over the kilometers of road within a municipality. The data allow us to control for a variety of independent variables. The project is able to include such variables as the class of accident, the condition of the driver, and the condition of the road surface, among others. There are 15 control variables overall. The expected effect of PPPs on road safety is ambiguous. PPPs may increase road safety if more resources are available for resurfacing, and if PPPs are incentivized through contracts to enhance safety. However, PPPs may reduce safety if private operators reduce road quality to increase profit maximize profits. The issue must be resolved empirically. Regarding methods, the study will begin with relatively simple statistical techniques such as ordinary least squares regression to estimate the determinants of traffic accidents and fatality rates. The project will include an indicator (dummy) variable for the type of operation: traditional or PPP. The project will include both time- and municipal-fixed effects, and will use robust standard errors. It is expected that this study will make a significant contribution to the literature on PPPs. This will be the first study to date to examine explicitly the effect of PPPs on traffic safety.]]></description>
      <pubDate>Tue, 08 Oct 2013 01:01:23 GMT</pubDate>
      <guid>https://rip.trb.org/View/1264495</guid>
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