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    <title>Transport Research International Documentation (TRID)</title>
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    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Transport Research International Documentation (TRID)</title>
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      <link>https://trid.trb.org/</link>
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      <title>Freeway Design Consistency Evaluation Model Based on Alignment and Traffic Characteristics</title>
      <link>https://trid.trb.org/View/2113980</link>
      <description><![CDATA[In order to identify the segments of China's highways that may have traffic safety hazards in the design phase, reduce the traffic accident rate and improve the operational safety of vehicles. This paper constructs a safety evaluation model based on design consistency applicable to China's highways, including the operating speed prediction model and design consistency evaluation indexes. Combined with actual cases, the effectiveness of the model is verified by comparing the constructed model, IHSDM and the evaluation method of “Specifications for Highway Safety Audit”. The results show that the accuracy of the model is 42% higher compared with IHSDM, and it can effectively evaluate the design safety of China's highways. It has important theoretical and practical significance for the study of highway design safety evaluation in China.]]></description>
      <pubDate>Tue, 28 Mar 2023 09:56:57 GMT</pubDate>
      <guid>https://trid.trb.org/View/2113980</guid>
    </item>
    <item>
      <title>WIS 75 Intersection Screening &amp; Project Development Process</title>
      <link>https://trid.trb.org/View/2003097</link>
      <description><![CDATA[This case study presents a safety analysis conducted by the Wisconsin Department of Transportation (WisDOT) at the intersection of State Highway 75 (WIS 75) and Plank Road (County Road A) in Racine County, WI. WisDOT proactively identified key safety needs early in the project development process and used a data-driven approach to evaluate the safety effects of potential alternatives. The corridor is scheduled for resurfacing in 2023, and through the network screening process, WisDOT identified an opportunity to develop a Highway Safety Improvement Program-related project in conjunction with routine maintenance. WisDOT’s diagnosis process reviewed recent crash history for potential contributing factors (e.g., driver behavior, sight distance, curvature, intersection geometry, etc.) and underscored the need to reduce failure-to-yield crashes. A preliminary intersection control evaluation eliminated infeasible alternatives early in the process and highlighted appropriate alternatives for further analysis. WisDOT applied State-calibrated safety performance functions in the Interactive Highway Safety Design Model software to predict crashes for each alternative and used State-approved crash modification factors where applicable. With these results, the economic appraisal step highlighted the most cost-effective alternative for this particular location. The State of the Practice methods and tools applied at each step in the process allowed WisDOT to thoroughly evaluate a safety need on its public road network as part of an institutional and readily repeatable planning process.]]></description>
      <pubDate>Wed, 24 Aug 2022 15:05:36 GMT</pubDate>
      <guid>https://trid.trb.org/View/2003097</guid>
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    <item>
      <title>Michigan’s US 31 at I-94 Interchange Alternatives Analysis</title>
      <link>https://trid.trb.org/View/2003096</link>
      <description><![CDATA[Since 1981, the Michigan Department of Transportation (MDOT) has worked with the Federal Highway Administration to complete the US 31 freeway connection between I-80/90 in northern Indiana to I-94 in Berrien County, Michigan. The latest construction on the US 31 freeway ended in 2003 with a terminal interchange at Napier Avenue in Berrien County. The original US 31 alignment planned to connect the new freeway to the existing I-94 and I-196 interchange northeast of Benton Harbor, Michigan. However, MDOT identified a sensitive natural resource and endangered species habitat south of the I-94 and I-196 interchange. Since this discovery, MDOT identified an acceptable tie-in at the I-94 and I-94 Business Loop partial interchange east of Benton Harbor. This case study presents MDOT’s iterative approach to project development that used the Interactive Highway Safety Design Model (IHSDM) software to identify a preferred design alternative based on a broad suite of traffic, safety, and cost considerations. The strategic application of IHSDM allowed MDOT to assess different design alternatives and project assumptions to make data-driven decisions for the proposed I-94 and US 31 interchange and surrounding network.]]></description>
      <pubDate>Wed, 24 Aug 2022 15:05:36 GMT</pubDate>
      <guid>https://trid.trb.org/View/2003096</guid>
    </item>
    <item>
      <title>West South Boulevard Redesign Safety Assessment</title>
      <link>https://trid.trb.org/View/2003092</link>
      <description><![CDATA[This case study summarizes a safety analysis conducted by the Federal Highway Administration (FHWA) Geometric Design Lab (GDL), in collaboration with the Alabama Department of Transportation (ALDOT) and the FHWA Alabama Division. GDL used the Interactive Highway Safety Design Model (IHSDM) software to assess the safety performance of W South Boulevard, a high-volume, high-speed suburban arterial in Montgomery, Alabama. This analysis supported a proposed access management design that included pedestrian improvements. The existing corridor lacked pedestrian accommodations but exhibited notable pedestrian activity and informal worn paths. The corridor also experienced a higher-than-expected number of crashes in recent years, particularly pedestrian crashes. GDL used the IHSDM’s Crash Prediction Model to predict annual crashes and compare the existing condition of W South Boulevard with the proposed redesign that included pedestrian safety improvements. The results of the data-driven analysis informed ALDOT’s decision-making on the project and increased confidence in the pedestrian safety elements selected for the final design. W South Boulevard represents a facility type that is common throughout the United States, especially where suburban and rural areas interface and mixed land uses are adjacent to major freeway corridors. This example showcases one way that data-driven safety analysis and crash prediction available through IHSDM can enable agencies to make informed investments in road user safety.]]></description>
      <pubDate>Wed, 24 Aug 2022 15:05:35 GMT</pubDate>
      <guid>https://trid.trb.org/View/2003092</guid>
    </item>
    <item>
      <title>Crash Distribution Dataset: Development and Validation for the Undivided Rural Roads in Oromia, Ethiopia</title>
      <link>https://trid.trb.org/View/1929801</link>
      <description><![CDATA[Predicting the number of crashes that may occur as a result of specific highway features is critical in evaluating different treatment or design alternatives. Since different highway geometric characteristics can influence crash distribution datasets, Highway Safety Manual's (HSM's) predictive method encourages users to predict crashes based on their severity and collision type proportions. This study used crash data from rural two-way two-lane road segments in the Oromia region over seven years to develop Oromia's fixed crash distribution dataset on Interactive Highway Safety Design Model (IHSDM) software. The crash distribution dataset has two parts; the crash severity proportions and the collision type percentages. The developed Oromia's fixed crash distribution dataset was compared and validated against the default HSM crash configuration. As a result, the Crash Prediction Model (CPM) evaluation results confirmed that the developed crash severity proportion (the first part of the crash distribution dataset) estimates are more accurate and closer to the observed values. Furthermore, the findings show that crashes in the Oromia region are severer than in the states where the HSM crash configuration was developed. According to the second part of the crash distribution dataset evaluation (collision type percentage), the developed fixed crash distribution dataset outperforms the default HSM configuration in most collision type proportions, but not in all. For instance, from the ten collision type proportions developed, Right-Angle and sides-wipe collision proportions are predicted more precisely by the default HSM configuration. This points to the need for developing collision type proportion (the second part of the crash distribution dataset) as a function rather than a fixed configuration for a better result, based on the availability of complete crash data (i.e. crash location). In general, the study revealed that in order to exploit the full potential of HSM's predictive approach, researchers must develop a jurisdiction crash distribution dataset using local crash data. The methodology demonstrated in this study to develop the jurisdiction's crash distribution dataset has been validated as true thus, safety practitioners are encouraged to adopt it.]]></description>
      <pubDate>Fri, 25 Mar 2022 12:08:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/1929801</guid>
    </item>
    <item>
      <title>Yale-Kilgore Road Safety and Traffic Assessment</title>
      <link>https://trid.trb.org/View/1885307</link>
      <description><![CDATA[This case study presents a safety analysis by the Federal Highway Administration, Western Federal Lands Highway Division (WFLHD) Highway Safety Team. The WFLHD used the Interactive Highway Safety Design Model (IHSDM) software as part of the design process for the rehabilitation of Yale- Kilgore Road. The Yale-Kilgore Road corridor is a county owned and operated two-lane undivided road located in Clark and Fremont counties in Idaho. The project corridor is an important recreational and commercial artery for the community. As a rural highway in and around a national forest, it has many unique challenges that may not exist in more urban and suburban environments. The Yale- Kilgore Road Safety and Traffic Assessment is a practical example of how the suite of IHSDM modules can support typical project development in an atypical context. Although the corridor is currently a mix of paved and unpaved surfaces, with speed and out-of-town traffic representing major concerns in both the present and the future, IHSDM assisted practitioners with the analysis tradeoffs necessary to make informed design and safety countermeasure decisions. The ability to analyze the corridor from a broad perspective (i.e., not crash prediction alone) allowed WFLHD to assess targeted improvements along the corridor, especially along segments of the corridor where the relative crash risk is highest.]]></description>
      <pubDate>Fri, 29 Oct 2021 15:40:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/1885307</guid>
    </item>
    <item>
      <title>Safer Roads Through Better Design: Using the Interactive Highway Safety Design Model</title>
      <link>https://trid.trb.org/View/1732610</link>
      <description><![CDATA[Improving roadway safety continues to be at the forefront of all stages of project development, including planning, alternatives analysis, design, construction, and operations. One tool available now to estimate a project’s substantive safety is the Interactive Highway Safety Design Model (IHSDM). IHSDM supports performance-based practical design (PBPD) via implementation of Highway Safety Manual (HSM) Part C predictive methods and can be an integral part of the Road Safety Audit process. The IHSDM contains six modules: Crash Prediction, Design Consistency, Intersection Review, Policy Review, Traffic Analysis, and Driver/Vehicle. This FREE software package helps users identify areas of safety concern within a given facility, and IHSDM outputs assist agencies in determining how to best invest limited resources to improve safety performance. Results from the model help project developers identify and justify safety-related design decisions. This brief document covers: using the crash prediction module to implement HSM Part C methods; evaluating safety performance using the IHSDM; using the IHSDM to evaluate alternative interchange designs; and IHSDM and road safety audits.]]></description>
      <pubDate>Thu, 10 Sep 2020 12:05:16 GMT</pubDate>
      <guid>https://trid.trb.org/View/1732610</guid>
    </item>
    <item>
      <title>Updating the Crash Modification Factors and Calibrating the IHSDM for Indiana</title>
      <link>https://trid.trb.org/View/1532585</link>
      <description><![CDATA[The Interactive Highway Safety Design Model (IHSDM) is a tool for assessing the safety impact of project-level design decisions by implementing the HSM crash prediction methodology. Safety Performance Functions (SPFs), Crash Modification Factors/Functions (CMFs), calibration factors, and crash proportions are utilized in predicting the number, severity, and type of crashes occurring on various types of roadway facilities. This study updated and expanded the set of CMFs applicable to Indiana conditions for various geometric, traffic, pavement, and other road characteristics. CMFs for 80 various road and control improvements for urban and rural segments, intersections, and interchanges. This report also presents the methodology of calibrating the IHSDM’s predictive components based on local data and past research. This method jointly estimates the SPFs and CMFs to preserve the crash prediction consistency. SPFs, CMFs, and crash proportions were calibrated for Indiana rural two-lane segments, rural divided multilane segments, and urban/suburban arterial segments. Example calculations showed that some results were only slightly affected while others vary considerably. This finding confirms the need for calibrating the parameters in the IHSDM to local conditions.]]></description>
      <pubDate>Mon, 27 Aug 2018 14:04:10 GMT</pubDate>
      <guid>https://trid.trb.org/View/1532585</guid>
    </item>
    <item>
      <title>Evaluation of the Restricted Crossing U-Turn Design as an Alternative to Grade Separated Interchanges on Rural Highways</title>
      <link>https://trid.trb.org/View/1496879</link>
      <description><![CDATA[Two-way stop-controlled (TWSC) intersections on four-lane rural highways rarely experience problems with congestion, but can be prone to higher than acceptable crash rates. In particular, crashes from entering left turn vehicles are among the most frequent, and have the most severe outcomes. Low-cost mitigations can reduce risk at these sites, but in extreme cases the facility can be reconstructed as a grade-separated interchange (GSI). While this is an effective solution in terms of safety, it is over-engineered and extremely costly for the demand volumes present. The restricted-crossing u-turn (RCUT) intersection design presents a cost-effective solution to mitigate safety concerns at TWSC intersections on rural highways. This study assesses the operational and safety expectations of TWSC, GSI, and RCUT facilities for different major road to minor road volume proportions. Case study sites were selected from among intersections currently being evaluated by the Nebraska Department of Transportation (NDOT) as potential GSI locations to resolve safety concerns. The base condition for traffic demand volume scenarios came from field data collection at a selected site in Palmyra, Nebraska. Results from VISSIM showed the GSI had the best operational performance, followed by the RCUT, and lastly the TWSC for all scenarios tested. Safety assessments using the Interactive Highway Safety Design Model predict that the RCUT intersection would greatly reduce crashes compared to the TWSC intersection, with better results than the GSI for some of the scenarios examined. Consequently, a cost-benefit analysis found the RCUT design to be the most cost-effective solution, recuperating construction costs within two years, with a 15-year return on investment for GSIs.]]></description>
      <pubDate>Thu, 22 Mar 2018 12:03:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/1496879</guid>
    </item>
    <item>
      <title>Application of IHSDM: KY 30 Case Study</title>
      <link>https://trid.trb.org/View/1484758</link>
      <description><![CDATA[A section of KY 30 in Jackson and Owsley Counties is targeted for redesign to provide a safer and more efficient corridor that will support economic activity in eastern Kentucky. Data for the existing KY 30 alignment and eight alternative alignments developed by HMB Professional Engineers Inc. were provided to researchers at the Kentucky Transportation Center (KTC). KTC researchers also developed a new alternative that modified the existing alignment to improve the safety of various locations. Researchers applied safety analysis procedures from Part C of the Highway Safety Manual (HSM) to the existing and alternative alignments of KY 30 using the Interactive Highway Safety Design Model (IHSDM). The resulting crash predictions were used to analyze each alternative and perform a benefit-cost analysis. Each alignment’s safety benefits were derived by calculating the total reduction in crashes (i.e., subtracting the number of crashes anticipated for an alternative from the number of crashes that would be expected if the segment were not redesigned). Comprehensive crash costs from the National Safety Council (NSC) were applied to the reduction in crashes to estimate, in monetary terms, the safety benefit. This figure was compared to the estimated cost of each project. KTC’s modified existing alignment had a benefit-cost (B/C) ratio of 0.14, meaning project’s cost outweighs the expected safety benefits. The other new build alternatives had negative B/C ratios, meaning the cost of crashes is expected to increase after their implementation. The increase in crash costs for the new build alternatives is due to the increase in crash severity expected on the new alignments coupled with the current alignment remaining a source of crashes (as the latter would remain open to facilitate the mobility of residents). IHSDM analysis only captures expected safety benefits, however. The selected alternative may be economically justifiable based on a holistic evaluation of the potential benefits it offers — in addition to safety benefits. The potential non-safety benefits of each project alternative should be analyzed to inform and improve the decision-making process for the KY 30 redesign.]]></description>
      <pubDate>Tue, 10 Oct 2017 17:41:36 GMT</pubDate>
      <guid>https://trid.trb.org/View/1484758</guid>
    </item>
    <item>
      <title>Road Safety Audit Case Studies: Using IHSDM in the RSA Process</title>
      <link>https://trid.trb.org/View/1455482</link>
      <description><![CDATA[Road Safety Audits (RSAs) are a formal safety performance examination of an existing or future roadway or off-road facility and are conducted by an independent, experienced, multidisciplinary team. The purpose of the Road Safety Audit Case Studies: Using IHSDM in the RSA Process is to help Federal, State, Tribal, and local agencies understand the benefits of using the Interactive Highway Safety Design Model (IHSDM) during the RSA process as a decision-support tool to evaluate and estimate the safety and operation of various design features. This case study document provides a review of the RSA process, an overview of IHSDM, and three case study examples of RSAs that utilized IHSDM. The case studies include photographs, a project background, how IHSDM was used, key RSA findings and suggestions, and the benefits of the IHSDM. These case studies will help jurisdictions incorporate this useful decision-support tool into the RSA process.]]></description>
      <pubDate>Wed, 22 Mar 2017 12:47:33 GMT</pubDate>
      <guid>https://trid.trb.org/View/1455482</guid>
    </item>
    <item>
      <title>Proposed Macro-Level Safety Planning Analysis Chapter for the Highway Safety Manual</title>
      <link>https://trid.trb.org/View/1407198</link>
      <description><![CDATA[The objectives of this research were to develop validated and demonstrated quantitative macro-level safety prediction models and a quantitative safety planning chapter for the AASHTO Highway Safety Manual (HSM) intended for use by transportation practitioners at all levels. This includes a guidance document on the development and application of these models, methods to integrate the model results into planning procedures, and electronic analysis tools for applying the models in practice. The research results are intended as a new chapter for inclusion in a future edition of the HSM. The results should address a broad range of safety planning level issues related to macro-level models such as, but not limited to, geography, demographics, transportation modes and modal interaction, existing or planned land-use and/or transportation projects, model transferability, calibration needs, and associated data limitations.]]></description>
      <pubDate>Thu, 12 May 2016 13:55:06 GMT</pubDate>
      <guid>https://trid.trb.org/View/1407198</guid>
    </item>
    <item>
      <title>Application of IHSDM Design Consistency Module and UK Operating Speed Prediction Model: A Case Study in the UK</title>
      <link>https://trid.trb.org/View/1270403</link>
      <description><![CDATA[Operating speed and design consistency have been agreed upon as the two critical measures of highway design evaluation, and could help researchers to study the contributors to traffic accidents and black-spots on roads. In the UK, Hashim has developed the most recent model since the first operating speed prediction model published in 1989. Comparably, much more research has been conducted in the USA, and a lot of achievements have been made. The Interactive Highway Safety Design Model (IHSDM) is a suite of evaluation tools for highway geometric design. Both of the two models are mainly focused on two-lane rural highways which also dominate the primary road classification in the UK. The major goals of this research are to find out the effectiveness of the highway design evaluation solution - IHSDM - applied on UK roads, as well as the further possible developments of the model developed by Hashim. The background of the two models has been investigated; furthermore, they have been implemented on carriageways to systematically evaluate their practical feasibility in the UK, especially for IHSDM. The comparisons of predicted operating speeds with collected speeds, as well as the appraisal of the results with traffic accident data both have been achieved. Finally, the further tasks that are required to make IHSDM appropriate for the UK conditions are recommended, including calibration of IHSDM Design Consistency Module to local situations and verification of highway alignment data input procedures of IHSDM; moreover, based on the results of applying Hashim's model, the constructive suggestions for its further development have been also presented in this report.]]></description>
      <pubDate>Sat, 24 May 2014 12:46:29 GMT</pubDate>
      <guid>https://trid.trb.org/View/1270403</guid>
    </item>
    <item>
      <title>Relationship between Predicted Speed Reduction on Horizontal Curves and Safety on Two-Lane Rural Roads in Spain</title>
      <link>https://trid.trb.org/View/1299723</link>
      <description><![CDATA[According to different studies, speed reduction is considered one of the major factors in contributing road safety. For that reason, several guidelines have been recommended for maximum desirable speed reductions from tangents to horizontal curves and for maximum differentials between design and operating speeds on horizontal curves. The Interactive Highway Safety Design Model (IHSDM) Design Consistency Module presents an analysis of the relationship between speed reduction and crashes for horizontal curves on U.S. two-lane rural highways. This paper presents the relationship between speed reduction and crashes for horizontal curves on Spanish two-lane rural roads. A model for using regression analysis to predict crashes is presented. Exposure, curve length (CL), and difference in 85th-percentile speeds (ΔV85) between successive tangents and horizontal curves, as well as between successive curves, are used. The model’s coefficients were different from the ones obtained for U.S. highways, although the values of the goodness-of-fit criteria were similar. In addition, the relationship between crashes and different speeds is analyzed, taking the difference in speed as a speed differential not exceeded by 85% of the drivers traveling under free-flow conditions (Δ85V), instead of considering it as ΔV85. The two models (ΔV85 versus Δ85V) give very similar results.]]></description>
      <pubDate>Fri, 21 Feb 2014 15:16:25 GMT</pubDate>
      <guid>https://trid.trb.org/View/1299723</guid>
    </item>
    <item>
      <title>Use of the Output of the Driver Vehicle Module of the IHDSM as Surrogate Measures for Departure Crashes</title>
      <link>https://trid.trb.org/View/1285693</link>
      <description><![CDATA[This paper presents the results of a research that investigates whether four output measures of the  Interactive Highway Safety Design Manual (IHSDM) Driver Vehicle Module (DVM), longitudinal and lateral Friction Ratios, Lateral Offset, and Roll-Over Index, follow the Normal distribution. The research then studies how the lateral offset can be used as a surrogate measure for departure crashes. The “UNIVARIATE” procedure of SAS software was used in the normality tests. Besides the graphical outputs, the skewness and Kurtosis values as well as the Shapiro-Wilk and the Anderson-Darling tests results were reviewed. For Lateral Offset, the authors could not reject the hypothesis that these data are normally distributed for results of 95 locations (α=5%). The results for longitudinal and lateral Friction Ratio, and Roll-Over Index were 73, 84, and 83 locations, respectively. The data used in this study come from running the DVM simulation on stretches of two-lane rural highways from Washington State. For the normality testing the simulation output of 100 randomly selected locations were studied. For studying the lateral offset as a surrogate measure the probabilities of Lateral Offset values exceeding the threshold values (encroachments) were calculated and the relations of these encroachments with departure crashes was studied. In this part of the study it was observed that for highways with narrow shoulders there exists a strong correlation between number of encroachments and the departure crash rates. The authors concluded that this measure can be used as a surrogate measures for departure crashes for this type of highway.]]></description>
      <pubDate>Fri, 24 Jan 2014 14:29:12 GMT</pubDate>
      <guid>https://trid.trb.org/View/1285693</guid>
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