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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>Introduction of the Barrier Equivalent Time (BET) Methodology in the Analysis of Delta-V</title>
      <link>https://trid.trb.org/View/1787415</link>
      <description><![CDATA[The determination of delta-V from the Barrier Equivalent Velocity (BEV) using energy analysis techniques such as CRASH3 is common in the field of accident reconstruction. This paper introduces a new methodology for determining delta-V in the field of accident reconstruction. Specifically it will introduce a linear analysis technique which utilizes the time to common velocity associated with two vehicles involved in an impact. This method employs all the assumptions used in the derivation of the CRASH3 damage based solution but rather than using an energy based solution a linear Barrier Equivalent Time (BET) method will be employed. This method requires the BEV, and thus the BET, of one of the vehicles involved in a collision and either the stiffness or the crush of the other vehicle. Instead of calculating the energies involved in the collision, the BET is used in conjunction with the time to common velocity in the impact. By remaining in the time domain the analysis remains linear and thus promotes a more coherent understanding between the BEV and delta-V relationship.]]></description>
      <pubDate>Mon, 13 Jan 2025 11:12:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/1787415</guid>
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      <title>Estimating the Speed Change and Relative Approach Speed of Aligned Offset Impacts using CRASH3 Techniques</title>
      <link>https://trid.trb.org/View/1829951</link>
      <description><![CDATA[CRASH3 techniques are often used to reconstruct aligned offset vehicle impacts. The goal of this study was to evaluate the accuracy of the CRASH3 technique using a series of aligned staged collision with varying degrees of overlap. Five front-to-rear vehicle impacts using the same vehicle model were staged using 25, 33, 50, 75 and 100% overlap. Impact kinematics were measured using overhead high speed video. The CRASH3 coefficients and methods developed previously (SAE 2010-01-0069) were used to reconstruct the impact speed and speed changes of both vehicles based on the residual crush. Overall, the CRASH3 analysis yielded good results for the 33 to 100% overlap collisions: predicted speed changes were within 29% of the measured speed change and predicted impact speeds were within 16% of the measured impact speed. The CRASH3 analysis yielded poor results for the 25% overlap collision: the predicted speed changes were up to 59% different from the actual speed changes and the predicted impacts speeds were up to 54% different from the actual impact speeds. These findings indicated that CRASH3 techniques can be used to reconstruct aligned offset impacts where the overlap is 33% or larger for collisions similar to those staged here.]]></description>
      <pubDate>Mon, 27 Jun 2022 08:59:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/1829951</guid>
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    <item>
      <title>Finite element method for reconstruction of road traffic accidents</title>
      <link>https://trid.trb.org/View/1577291</link>
      <description><![CDATA[The article examines the accident rate statistics on the roads of the Russian Federation, analysis of which provides the basis for posing the issue of improving the quality of expert study of road traffic accidents. The theory of the finite element method is studied and an algorithm for simulating road traffic accidents is proposed, which is based on the analysis of deformation damage to a vehicle and calculation by finite element method. The proposed algorithm is used to calculate the vehicle speed during frontal impact with an undeformable obstacle. The result is verified by calculating the fraction of kinetic energy expenditure (ΔЕ) for development of deformations and the speed equivalent to this expenditure by “Crash3” algorithm. The analysis of the obtained data showed high efficiency of the algorithm proposed by the authors.]]></description>
      <pubDate>Mon, 11 Feb 2019 16:33:51 GMT</pubDate>
      <guid>https://trid.trb.org/View/1577291</guid>
    </item>
    <item>
      <title>An Overview of NHTSA’s Crash Reconstruction Software WinSMASH</title>
      <link>https://trid.trb.org/View/1367870</link>
      <description><![CDATA[The National Highway Traffic Safety Administration (NHTSA) uses WinSMASH computer software to estimate the change in velocity, delta-V, of the vehicles involved in crashes. The software uses detailed measurements from the crash scene, vehicle damage and vehicle stiffness characteristics to compute energy absorbed by the vehicle and estimate the delta-V and Barrier Equivalent Speed (BES). The WinSMASH is a Microsoft Windows based, enhanced and updated version of the accident reconstruction software CRASH3 previously used by NHTSA. The purpose of this paper is to describe the new enhancements in the program. The damage algorithm used in CRASH3 has been reformulated in WinSMASH. The new damage algorithm in WinSMASH is based on an assumed linear relationship between crash energy and crush and uses intercept d₀ and slope d₁ to describe vehicle stiffness. The software uses generic vehicle size and stiffness categories based on the vehicle’s wheelbase. However, the program also allows the users to enter the vehicle specific stiffness coefficients. The stiffness coefficients for a large number of vehicles have been calculated from crash test results and integrated into WinSMASH. An automated procedure to select the vehicle specific stiffness coefficients is currently under development. A statistical model is also being developed for estimating the stiffness coefficients of a vehicle that is not crash tested. The paper provides an overview of these procedures. The WinSMASH estimated delta-V of the vehicles is compared with the corresponding delta-V obtained from the Event Data Recorder (EDR) installed in the crashed vehicles to assess the accuracy of the software. The staged crash tests used to validate the software are also discussed in the paper.]]></description>
      <pubDate>Fri, 25 Sep 2015 16:19:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/1367870</guid>
    </item>
    <item>
      <title>The Implications of the CRASH3 Uniaxial Structural Response Model and the Nature of Available Collision Test Data in Regards to Work-Energy Relationships for Oblique Impacts</title>
      <link>https://trid.trb.org/View/1365884</link>
      <description><![CDATA[This article discussed the Calspan Reconstruction of Accident Speeds on the Highway (CRASH3) algorithm. The algorithm is used for quantifying the severity of a collision based upon the residual damage present to the collision partners. The article described how the reconstruction of motor vehicle collisions for inclusion in the National Automotive Sampling System (NASS) Crashworthiness Data Systems (CDS) involved the use of a damage analysis algorithm or a trajectory algorithm. The collision characteristics that fall within the CRASH3 algorithm are classified as planar impacts, inclusive of collinear collisions.]]></description>
      <pubDate>Fri, 28 Aug 2015 13:56:44 GMT</pubDate>
      <guid>https://trid.trb.org/View/1365884</guid>
    </item>
    <item>
      <title>Evaluation of the Accuracy of Side Impact Crash Test Reconstructions</title>
      <link>https://trid.trb.org/View/915017</link>
      <description><![CDATA[This paper describes how side-impact crashes claim over 6000 lives every year in the United States (U.S.). Policy and research efforts designed to mitigate the death toll from this crash mode rely heavily upon estimations of the delta-V in real-world crashes. Many of the delta-V estimations for side crashes found in commonly used databases are made using the CRASH3 reconstruction algorithm. Thus, the accuracy of CRASH3 delta-V estimations for side crashes is of critical importance to a wide body of research and policy. This study was performed to help assess the accuracy of CRASH3 when reconstructing side impacts.]]></description>
      <pubDate>Wed, 14 Apr 2010 07:14:12 GMT</pubDate>
      <guid>https://trid.trb.org/View/915017</guid>
    </item>
    <item>
      <title>DIFFERENCES BETWEEN EDCRASH AND CRASH3</title>
      <link>https://trid.trb.org/View/272332</link>
      <description><![CDATA[Motor vehicle accident researchers have used the CRASH computer program for some time.  Over the years, the code was upgraded until it reached its present and popular form, CRASH3, which runs on a mainframe computer or minicomputer with a sizeable memory capacity. A new version of the program, EDCRASH, has been developed which runs on personal computers using 128K of memory. This paper describes and compares this program with its mainframe counterpart.  The program performed the same function as CRASH3, but was designed as a screen-oriented program utilizing the environment of the personal computer.  Its design also allowed for file saving, graphics, routing of output, and interfacing with other accident reconstruction programs.  For most accident types, the results for both programs were identical.  However, for some types the results were different.]]></description>
      <pubDate>Fri, 31 Jan 1986 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/272332</guid>
    </item>
    <item>
      <title>INACCURACIES IN THE CRASH3 PROGRAM</title>
      <link>https://trid.trb.org/View/272334</link>
      <description><![CDATA[The CRASH3 computer program, a well known and useful tool in accident reconstruction, is shown to be inaccurate by comparison with car-to-car crash test data. Claims for accuracy of about 10 percent cannot be validated. Both the impact model and the damage only model yield results which are in error.  Cases involving error well in excess of 20 percent are demonstrated.  These inaccuracies are due primarily to the omission of terms in the formulation of the energy equation and to the sensitivity of the solution to the input estimate of principle-direction-of-force.]]></description>
      <pubDate>Fri, 31 Jan 1986 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/272334</guid>
    </item>
    <item>
      <title>BARRIER EQUIVALENT VELOCITY, DELTA V AND CRASH3 STIFFNESS IN AUTOMOBILE COLLISIONS</title>
      <link>https://trid.trb.org/View/272339</link>
      <description><![CDATA[Accident Investigators have occasionally and mistakenly assumed that the magnitude of the Change of Speed (delta V) during an auto collision is simply proportional to the post collision crush of the automobile.  This paper reviews the introduction of the Vehicle Deformation Index, Collision Deformation Classification, Barrier Equivalent Velocity (BEV), Stiffness of the other vehicle, and the appropriate delta V.  Presented are some practical worked examples deriving delta V and comparing it with crush and BEV for each deformed automobile.  Change of Speed is also reviewed for crashes into deformable barriers and compared with post collision deformation and BEV.  The crush magnitude of three types of non-symmetrical frontal collisions are studied and compared with BEV.  The crash test stiffness of recent models and the CRASH3 crush parameters are compared.]]></description>
      <pubDate>Fri, 31 Jan 1986 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/272339</guid>
    </item>
    <item>
      <title>NEW TECHNOLOGIES AND TECHNIQUES FOR NASS ACCIDENT INVESTIGATIONS</title>
      <link>https://trid.trb.org/View/272344</link>
      <description><![CDATA[The National Accident Sampling System (NASS) has investigated more than 40,000 traffic accidents in its six years of operation.  This paper discusses some of the new technologies and techniques of accident investigation being adopted in NASS.  These include a microcomputer data entry system, the CRASH 3 program for estimating the severity of an impact, a contour gauge for measuring vehicle deformation, and automated scene diagramming techniques.  The authors also define some of the unsolved problems in mass accident investigation, and discuss the constraints on solving them.]]></description>
      <pubDate>Fri, 31 Jan 1986 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/272344</guid>
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