Journal of the National Academy of Forensic Engineers

Methodology for Reconciliation of Different Forms of Electronic Data in Vehicle Collision Reconstruction

2022-11-10T02:52:39+00:00

Collision analysis utilizing electronic data recorders, videos, traffic signal timing data, and other electronic records adds valuable input but can be a challenge to tie together due to the lack of a finite time stamp or common recording rate. However, overlapping data streams that have a common point-in-time identifier can be resolved. A strategic approach was developed by the author for unifying and validating the vehicle positions and time-distance reconstruction. The method outlines the steps for establishing known data points, forming a common time line, identifying overlapping information, and linking together independent records. A case study demonstrates a crash at a traffic signal-controlled intersection in which each vehicle entered on their respective green lights without conflict; however, the collision still occurred. The crash reconstruction will highlight driver options and demonstrate the value of combining multiple data streams into one time line.

Factors to Consider in Developing Conceptual Scopes of Repair for Common Low-Slope Roofing Assemblies

2023-05-09T23:25:03+00:00

Forensic engineers are commonly asked to develop conceptual scopes of repair as part of their work. Many factors impact these recommendations, including building codes, construction feasibility, manufacturer assessment, and installation requirements. In addition, the conditions present on and within the existing roof surfaces can limit the repairability of a commercial roof assembly such that removal and replacement of the entire roof section is the appropriate or only feasible repair option. This paper will focus on common limitations to be considered when developing a conceptual scope of repair for common commercial roof systems, including single-ply membranes, built-up roofing, metal panel roofing, spray polyurethane foam roofing, and the application/maintenance of roof coatings. It will also discuss an assessment methodology that can assist in developing a broader understanding of the condition of the roof surfaces.

Utilizing ASCE/SEI 7 to Estimate Wind Speeds for Forensic Investigations

2023-08-24T02:07:17+00:00

The American Society of Civil Engineers/Structural Engineering Institute (ASCE/SEI) 7 standard is utilized to determine design wind loading on buildings and other structures. However, it can also be utilized in a forensic capacity to approximate a wind speed that would cause specific conditions to occur, such as the overturning of a structure. This paper provides a brief overview of the ASCE/SEI 7 method for wind loading and discusses the use of various adjustment factors used to determine the wind on structures, including wind directionality factor, velocity pressure coefficient, topographic factor, and the ground elevation factor. A clear understanding of these factors — and how to apply them — is crucial to estimating a wind speed and resulting force to cause a particular event or condition to occur.

Forensic Engineering Investigation of a Machine Guarding-Related Injury

2023-06-12T00:24:18+00:00

OSHA regulations and industry-accepted standards are intended to be used in conjunction to help prevent worker injury. Despite the aforementioned intention, a point of operation injury occurred to an employee while he was operating a hydraulic rotary bending machine. The machine had been retrofitted with a two-hand control device that was intended to act as a means of point of operation safeguarding. A forensic engineering analysis of both the electromechanical design and programmable logic code — combined with a performance and prescriptive requirement analysis — ultimately revealed flaws in the design of the electromechanical system and software design. It also demonstrated a lack of adherence to the applicable industry-accepted standards related to machine guarding. These factors led to the point of operation injury.

Investigation and Root Cause Analysis of Transformer Metering Destruction by Arc Flash

2023-10-04T18:36:38+00:00

An arc flash and fire in the secondary compartment of an industrial facility utility transformer resulted in destruction of newly installed electrical metering equipment. Inherent to this type of event are two loss-of-evidence challenges: extremely high heat burns or melts everything nearby, and urgency to restore normal operation may prevent comprehensive examination of the scene. The facility contractor’s operations staff conducted an initial root cause analysis. The contractor’s management called on an external forensic team to provide an independent assessment. Having an established investigation methodology allows the forensic examiner to better understand what was, and was not, evaluated by facility staff and prevents confirmation biases. This paper examines the facility’s report, addresses shortcomings in its conclusions, and goes on to detail the methods and reasoning behind the forensic team’s findings. The methodology presented in this paper is applicable to a wide range of industrial electrical fires.

FE Investigation of Design and Quality Control-Related Issues Contributing to Metal-On-Metal Hip Implant Failures

2023-06-13T01:16:38+00:00

High levels of cobalt and chromium ions were detected in the bodies of multiple recipients of modular cobalt chrome molybdenum metal-on-metal hip implants, necessitating the revision of their implants. A forensic engineering investigation of provided discovery documents and existing literature regarding the design, manufacturing, and clinical testing of these modular hip implants was performed. The investigation revealed that the modular interfaces of the implant allowed for micromotion to induce mechanically assisted crevice corrosion at these surfaces. The debris from this corrosion resulted in the release of metal ions into the bodies of the users, forming pseudotumors and compromising the user’s health and wellbeing. The effect of this corrosion was enhanced by the galvanic couple that existed between the modular components of the implant. In addition, scanning electron microscopy (SEM) and electron dispersive spectroscopy (EDS) analysis identified silicon carbide (SiC) and aluminum oxide (AL2O3 ) particles left behind from polishing, which were embedded in the ball and liners. These particles accelerated the wear of the hip implant and further exacerbated the release of metal ions. The designers of future hip implants should take care in preventing the occurrence of the above-stated factors.

FE Investigation of Maintenance and Operational Factors Contributing to the Collapse of a Crane Boom

2023-04-21T01:56:37+00:00

During the coating of a natural gas pipeline, all 14 bolts securing the pedestal of a crane boom to a truck bed failed, causing the boom to fall and strike a worker in the head. The bolts exhibited excessive corrosion indicative of exposure to a harsh corrosive environment prior to the failure. Review of provided documents revealed that the crane was kept in an uncovered yard for two years. Afterward, it was rented to petrochemical companies for use in heavy oil and gas industrial environments. The fracture surfaces of the bolts revealed signs of excessive fatigue, which were determined to be caused by loadings that the previous renters of the crane had subjected it to. Bolt fatigue drastically reduced their strength, allowing them to fail under loads well below the recommended load capacity of the crane. Maintenance records indicated that the lessor failed to perform adequate inspection of the crane, allowing bolt corrosion and fatigue to go unnoticed. Had proper inspections and maintenance instructions been provided and performed, the incident would not have occurred.