Total Station Surveying Technology for Forensic Mapping

Total Station Surveying Technology for Forensic Mapping of Fire and Explosion Incident Scenes

Brian C. Dunagan, CSP, CFEI, CFII
IFO Group, Inc. – Incident Free Operations, Inc., USA
Christopher F. Schemel, Ph.D.
IFO Group, Inc. – Delta Q Consultants, Inc., USA

ABSTRACT
Total stations (electronic surveying equipment) are frequently used in traffic accident investigations to collect data for reconstruction specialists. For more than 20 years these devices have dramatically reduced the time and labor required to document and map vehicle accident scenes. The data collected by a total station can be easily imported into modeling and sophisticated mapping software. This technology can be deployed in other forensic applications and can be readily used to assist investigators in systematically and accurately mapping fire and explosion incident scenes. This paper summarizes the role a total station plays in forensic mapping. First, an overview of forensic mapping using total stations and associated equipment such as prisms and data collectors is presented. Second, the constraints and the legal considerations of the technology are discussed. Third, a case study using forensic mapping of an explosion scene is presented. Finally, it will be demonstrated that the use of these techniques can assist the savvy investigator in building a compelling case narrative that builds on and complements other evidence collected while satisfying the ever increasing standards for reliable and accurate documentation of scenes.

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Misuse of Simple Explosion Tools in Complex Explosion Investigations

Misuse of Simple Explosion Tools in Complex Explosion Investigations

Scott Davis, Ph.D., P.E., CFEI
Derek Engel, CFEI
Tom DeBold
Peter Hinze, Ph.D., P.E., CFEI
And
Bryant Hendrickson
GexCon US, U.S.A.

Presented at the International Symposium on Fire Investigation Science and Technology, 2014

ABSTRACT

There are numerous simple models that can be used to assist the investigation into fuel-air explosions. These models include simple equilibrium based unvented explosions, single and multiple vent equations for large vessels and rooms, constant flame speed models with completely unconfined and fixed congestion (e.g, TNO Multi-energy model, BST method), TNT equivalent models that compare explosion consequences for gas phase explosions with TNT, etc. Some of these simplified methods can help predict both the free-field blast pressure, as well as the dynamic effects due to the venting of the expanding cloud (e.g., drag forces resulting from the blast wind).

While these models may be appealing to assist in an investigation, extreme caution needs to be exercised when using these models outside their intended application. For example, asymmetries and non-uniform congestion, or partially confined structures can result in simple tools vastly over or under-predicting explosion loads and the associated dynamic effect. This data is oftentimes critical in an accident investigation. This paper will present a variety of case studies where simple tools were incorrectly applied to complex explosion investigations, resulting in incorrect opinions regarding the incident. In contrast, the paper will compare the simplified results with those obtained using more advanced CFD modeling.

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Complex Explosion Development in Mines: Case Study

Complex Explosion Development in Mines: Case Study – 2010 Upper Big Branch Mine Explosion

Scott David, Ph.D., P.E., CFEI
Derek Engel, CFEI
Kees van Wingerden, Ph.D.
GexCon, US, USA

ABSTRACT
On April 5th, 2010 a methane explosion occurred within the Upper Big Branch mine south of Charleston, WV. Twenty-nine men lost their lives as a result of a flammable concentration of methane that built up in the enclosed space and ignited, resulting in a methane explosion that transitioned into a coal dust explosion. This study used the FLACS CFD solver to conduct a detailed explosion analysis to evaluate the complex overpressure development throughout the mine as a result of the flammable cloud ignition. As a result of the accident investigation, unique explosion patterns were found in the mine where certain “blast indicators” within the mine shafts were deformed in such a manner that was inconsistent with the likely flow of the expanding blast wave. The FLACS analysis will analyze the explosion dynamics and shed light on the damage observations made after the blast.

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Fire Effects on Receptacles

Matthew E. Benfer, Daniel T. Gottuk
Hughes Associates Inc., USA

Presented at the International Symposium on Fire Investigation Science and Technology, 2012

ABSTRACT

Although significant casualties and damage are attributed to electrical fires, there is still much uncertainty in clearly identifying forensic indicators of electrical components post-fire to be able to justify whether the component damage was a result of the fire (i.e., a fire victim) or whether it signifies a cause. The objective of this study was to assess the damage and potential forensic signatures of a range of electrical receptacle configurations exposed to two types of fires in order to provide a technical basis for realistic electrical fire scenarios, improving fire scene interpretation, and evaluating the utility of forensic analysis techniques. Specifically, the approach was to, first, characterize the damage (e.g., location of damage, melt, arcing, etc.) to receptacle configurations that have been the source of overheating and compare this to data for receptacles exposed to fire. A second objective was to characterize the similarities and differences between arcing and melting in receptacle components and wiring.

Laboratory testing evaluated the impact of a wide range of variables on the formation of overheating connections in residential duplex receptacles. Two types of receptacle configurations have been evaluated: 1) those focused on terminal connections and 2) those focused on plug connections. Testing included 528 receptacle trials, 408 trials with various terminal connections and 120 trials with various plug connections. Thirteen pre-fabricated wall assemblies of 36 receptacles were placed in 8 compartment fire tests and 5 furnace fire tests. The variables evaluated in the fire exposure testing included: the receptacle material, materials of the receptacle faceplate and box, terminal torque, and energized state of the receptacle. A portion of receptacles in the fire exposure testing had overheated connections that were created in the laboratory testing. These receptacles were used to assess whether evidence of overheating would persist after a fire exposure. All receptacles were documented for damage to the receptacle, faceplate, and outlet box including any arcing, overheating, and/or melting.

The results of laboratory testing indicate that only the loosest connections tend to form significant overheated connections irrespective of other variables such as receptacle materials and installation. Characteristics of damage to receptacles as a result of overheating have been identified and have been found to persist even after fire exposure. In addition, locations of arcing within receptacles as a result of fire exposures were identified and characterized. The location of arcing is primarily dependent on the duration and intensity of the fire exposure, as well as the construction and materials of the receptacle, outlet box, and faceplate.

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Observations on Two Fires

Observations on Two Fires in Which the Spill of Flammable Liquids Led to Deflagration and/or Flash Fire in a Stratified Heavy Vapor/Air Mixture

Giovanni Cocchi, P.E., Ph.D.
ARSON Fire, Safety and Environmental Investigations S.r.l., Italy

Presented at the International Symposium on Fire Investigation Science and Technology, 2014

ABSTRACT

The most common kind of diffuse phase explosions investigated by fire investigators involve methane or LPG, either accidentally or willingly allowed to accumulate in the confined volume of the room(s) of a building. Many volatile ignitable liquids can form a flammable vapor/air mixture when spilled on the floor and let evaporate for enough time. Upon ignition, flash fire or deflagration will take place, possibly followed by the development of a compartment fire. This work reviews the relevant literature about evaporation of volatile ignitable liquids, heavy gas dispersion and propagation of flame front in stratified heavy vapor/air mixtures. Subsequently, two cases in which the author was asked to provide its technical opinions will be discussed. The first one is a massive semi-confined deflagration in a large storage room that eventually vented through the weakest brick wall of the building. The building was not equipped with natural gas lines and no LPG can was retrieved at the scene. Subsequent fire debris analysis demonstrated the use of volatile accelerants. The second one is a flash fire that was caught on CCTV camera. Around four minutes before, a person was taped while pouring a liquid…After the flash fire, the puddles of liquid of what was intended to be a trailer were observed to burn as pool fires, until smoke obscured the camera. The flame front of the flash fire shows all the relevant features that other authors have previously shown to be peculiars of flash fires in a stratified heavy vapor/air mixture. Fire investigator should consider that when an explosion or a flash fire take place before fire development and natural gas or LPG sources can be legitimately ruled out, use of highly volatile accelerants should be regarded as a legitimate hypothesis and tested according to the scientific method of NFPA 921-2014 .

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Measuring the Impact of Cognitive Bias

Measuring the Impact of Cognitive Bias in Fire Investigation

Paul Bieber, CFEI, B.S., M.L.S.
Director of the Arson Research Project, USA

Presented at the International Symposium on Fire Investigation Science and Technology, 2012

ABSTRACT

Cognitive bias has been found to shape decision making in a wide variety of fields. Criminal investigation and the forensic sciences are no exception.  Fire investigation, part criminal investigation, part forensic examination, is uniquely positioned to be influenced by the affects of cognitive bias.

The 2009 report from the National Academy of Science, Strengthening Forensic Science in the United States; A Path Forward (NAS Report) , recognizes conceptual bias as a factor in all forensic disciplines.  The National Fire Protection Association Guide for Fire and Explosion Investigation (NFPA 921)  acknowledges these biases as a concern in fire investigation.3

This report will explore the most common forms of cognitive bias found in the field of fire investigation, review past research and give recommendations on how these biases might be minimized. It will also present the results of new research which sought to measure the influence of expectation and role bias in fire investigation. A companion report, “Case Study Review of Contextual Bias in Fire Investigation” is available at www.Thearsonproject.org.

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The Differences Between the North American Building Constructions and the Southern European Building Constructions

The Differences Between the North American Building Constructions and the Southern European Building Constructions Affects the Type of Fire Pattern That Are Most Commonly Found in a Fire Scene

Giovanni Cocchi, P.E., Ph. D.
ARSON Fire, Safety, and Environmental Investigations S.r.l., Italy

Presented at the International Symposium on Fire Investigation Science and Technology, 2014

ABSTRACT

Fire pattern analysis is a fundamental step in any fire investigation, since it provide the basis for the heat and flame vector analysis onto which the reconstruction of fire spread and the identification of the area of origin of the fire are based. Fire patterns formation depends on the fire effects being produced by the fire. This works discuss some of the differences between building construction in North America and Southern Europe, on the basis of the example of Italy, and try to tackle the problem if such differences may affects the type of fire patterns that are found in a fire scene.

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Arc Mapping: A Review of Findings and a Reply to the ATF Laboratory

There has been a lot of debate in fire investigation industry recently regarding Arc Mapping.  NAFI’s mission is to increase the knowledge and improve the skills of persons engaged in the investigation and analysis of fires, explosions and arsons, or the litigation that ensues from such investigations. The opinions expressed in this paper do not necessarily reflect the opinion and beliefs of NAFI. Over the next three weeks, we will be sharing different views on Arc Mapping with our members and the industry – it is up to you to draw your own conclusions.

Week 1 – Arc Mapping: New Science or New Myth?
Week 2 – Arc Mapping as a Tool for Fire Investigations
Week 3 – Arc Mapping: A Review of Findings

Abstract
The ATF Laboratory recently issued Special Bulletin No. 2 which offered a series of objections to the arc mapping review presented by this author earlier this year. This paper reviews the original research findings and explains the context of these findings. It then addresses in detail the comments made by ATF, and further addresses the concerns about arc mapping as currently used in the field. It reaffirms that the original findings are correct. It also shows that a new “ellipse” method proposed by the ATF for origin determination from arcing locations is not technically sound.

Download the complete paper here

 


Analysis of Post-Fire Characteristics of Portable Oil Filled Room Heaters

Analysis of Post-Fire Characteristics of Portable Oil Filled Room Heaters to Determine Pre-Fire Orientation

K. Scott Barnhill, PE
Investigative Forensic Specialists, PLLC

Presented at the International Symposium on Fire Investigation Science and Technology, 2014

ABSTRACT
A portable oil filled room heater is a steel vessel typically with 5 to 8 fins containing approximately 3 to 4 liters of mineral oil. The mineral oil acts as the heat transfer fluid that is heated by an immersed electric heating element. The outward appearance of an oil filled heater is that of an old steam radiator.

An oil filled heater (OFH) exposed to full room involvement conditions will commonly display fire effects to include: rupture of the vessel’s spot welds, localized wavy deformations to the fins in the unwetted regions of the vessel, and differential deformation of the vessel’s fins. This study addresses the post-fire characteristics of oil filled heaters exposed to full room involvement conditions in two burn cells. A primary focus of the study is to determine if the pre-fire orientation of the oil filled heater can be determined by analysis of the post-fire appearance. A description of the dynamics that occur between the wetted and unwetted surfaces when the vessel is exposed to full room involvement conditions is discussed.

Analysis of an OFHs’ post-fire characteristics, to include vessel dimensions and wavy deformations, compared to the burn cell experiment results, allows an investigator to accurately interpret the normal reaction of an OFH to full room involvement as well as to determine its pre-fire orientation (upright or otherwise).

Download the complete paper here


Arc Mapping as a Tool for Fire Investigations

There has been a lot of debate in fire investigation industry recently regarding Arc Mapping.  NAFI’s mission is to increase the knowledge and improve the skills of persons engaged in the investigation and analysis of fires, explosions and arsons, or the litigation that ensues from such investigations. The opinions expressed in this paper do not necessarily reflect the opinion and beliefs of NAFI. Over the next three weeks, we will be sharing different views on Arc Mapping with our members and the industry – it is up to you to draw your own conclusions.

Week 1 – Arc Mapping: New Science or New Myth?
Week 2 – Arc Mapping as a Tool for Fire Investigations

ATF Fire Research Laboratory Technical Bulletin
Arc Mapping as a Tool for Fire Investigations

ABSTRACT
The purpose of this Technical Bulletin is to address statements that are contained in Arc Mapping: New Science or New Myth?, which was presented at the Fire and Materials Conference in February 2017. The paper’s interpretations and analysis of the published literature, the limitations it places on the process of arc mapping, and the conclusion that arc mapping is applicable to less than 1% of fire scene investigations are misleading. This bulletin addresses some of these issues.

Download the entire technical bulletin here.