Stephen Fenton, PE
Executive Vice President | Accident Reconstruction Practice Lead | J.S. Held LLC
Greenwood Village, CO, UNITED STATES
Professional Engineer | Traffic Accident Reconstructionist | Expert Witness | Photogrammetry specialist | Engineering Technical Author
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Biography
Stephen Fenton joined J.S. Held in July of 2021 as part of J.S. Held's acquisition of Kineticorp. Mr. Fenton is a registered Professional Engineer in the State of Colorado and he is accredited as a Traffic Accident Reconstructionist through the Accreditation Commission for Traffic Accident Reconstruction (ACTAR). He holds a degree in Engineering from the Colorado School of Mines. Mr. Fenton investigates and reconstructs vehicular accidents and provides expert testimony in state and federal courts for both defendants and plaintiffs. He chaired the Photogrammetry Committee for the Society of Automotive Engineers (SAE) from 2001 to 2012 and participated as a team member in the Accident Investigation and Accident Reconstruction Standards Committee (AIARSC). As a part of the AIARSC, he participated in the following subcommittees: Investigation Techniques, Vehicle Road Friction, Reconstruction Analysis, Information Resources, and Motor Vehicle Fire Investigations Task Force.
Mr. Fenton has given presentations and lectures at a number of national and international technical conferences, including the Society of Automotive Engineers’ World Congress and Northeastern University’s Symposium on Criminal Justice. He conducts seminars for regional bar associations and engineering societies on photogrammetry and vehicular accident reconstruction. He has authored numerous technical articles in the areas of accident reconstruction, photogrammetry, and computer animation, which have been published in the SAE’s Technical Paper Series, Accident Reconstruction Journal, and the National Academy of Forensic Engineers. Mr. Fenton is the recipient of the prestigious 2006 Arch T. Colwell Merit Award. He has been awarded grants related to photogrammetric documentation and has been listed as a training specialist for close-range photogrammetry software. Mr. Fenton’s accident reconstruction expertise has been featured on such television programs as MSNBC’s “Why Cars Crash,” Discovery Channel’s “Discover Magazine – The Science Behind the Headlines” and NBC’s News Magazine “Dateline.”
Industry Expertise (2)
Automotive
Legal Services
Areas of Expertise (8)
Forensic Engineering
Accident Reconstruction
Vehicle Dynamics
Occupant Kinematics
Photogrammetry
Computer Modeling
Vehicle & Product Testing
Expert Testimony
Accomplishments & Recognitions (1)
Arch T. Colwell Merit Award (professional)
2006 Society of Automative Engineers
Affiliations (6)
- SAE (Society of Automotive Engineers) : Member
- Photogrammetry Committee for the Society of Automotive Engineers (SAE) : Former Chair
- ASCE (American Society of Civil Engineers) : Member
- SPIE (The International Society of Optical Engineering) : Member
- ASPRS (American Society of Photogrammetry and Remote Sensing) : Member
- AIARSC (Accident Investigation and Accident Reconstruction Standards Committee) : Team Member
Articles (8)
Reconstruction of 3D Accident Sites Using USGS LiDAR, Aerial Images, and Photogrammetry
WCX SAE World Congress Experience2019 The accident reconstruction community has previously relied upon photographs and site visits to recreate a scene. This method is difficult in instances where the site has changed or is not accessible. In 2017 the United States Geological Survey (USGS) released historical 3D point clouds (LiDAR) allowing for access to digital 3D data without visiting the site. This offers many unique benefits to the reconstruction community including: safety, budget, time, and historical preservation. This paper presents a methodology for collecting this data and using it in conjunction with aerial imagery, and camera matching photogrammetry to create 3D computer models of the scene without a site visit.
Determining Vehicle Steering and Braking from Yaw Mark Striations
SAE World Congress & Exhibition2009 This paper presents equations that relate the orientation and spacing of yaw mark striations to the vehicle braking and steering levels present at the time the striations were deposited. These equations, thus, provide a link between physical evidence deposited on a roadway during a crash (the tire mark striations) and actions taken by the driver during that crash (steering and braking inputs).
A Method to Quantify Vehicle Dynamics and Deformation for Vehicle Rollover Tests Using Camera-Matching Video Analysis
SAE World Congress & Exhibition2008 This paper examines the use of camera-matching video analysis techniques to quantify the vehicle dynamics and deformation for a dolly rollover test run in accordance with the SAE Recommended Practice J2114. The method presented enables vehicle motion data and deformation measurements to be obtained without the use of the automated target tracking employed by existing motion tracking systems.
Occupant Ejection Trajectories in Rollover Crashes: Full-Scale Testing and Real World Cases
SAE World Congress & Exhibition2008 A simple two-dimensional particle model was previously developed to calculate occupant ejection trajectories in rollover crashes. Model parameters were optimized using data from a dolly rollover test of a 1998 Ford Expedition in which five unbelted anthropomorphic test devices (ATDs) were completely ejected. In the present study, the model was further validated against a dolly rollover test of a 2004 Volvo XC90 in which three unbelted ATDs were completely ejected.
The Influence of Vehicle-to-Ground Impact Conditions on Rollover Dynamics and Severity
SAE World Congress & Exhibition2008 This paper explores the influence of the impact conditions on the dynamics and the severity of rollover crashes. Causal connections are sought between the impact conditions and the crash attributes to which they lead. The paper begins by extending previously presented equations that describe the dynamics of an idealized vehicle-to-ground impact. It then considers the behavior of these equations under a variety of impact conditions that occur during real-world rollovers.
Analysis of Vehicle-to-Ground Impacts During a Rollover with an Impulse-Momentum Impact Model
SAE World Congress & Exhibition2008 This paper explores the accuracy of a planar, impulse-momentum impact model in representing the dynamics of three vehicle-to-ground impacts that occurred during a SAE J2114 dolly rollover test. The impacts were analyzed, first, using video analysis techniques to obtain the actual velocity conditions, accelerations, impact force components and the energy loss for each of the impacts.
Image Analysis of Rollover Crash Tests Using Photogrammetry
SAE World Congress & Exhibition2006 This paper presents an image analysis of a laboratory-based rollover crash test using camera-matching photogrammetry. The procedures pertaining to setup, analysis and data process used in this method are outlined. Vehicle roll angle and rate calculated using the method are presented and compared to the measured values obtained using a vehicle mounted angular rate sensor.
A Video Tracking Photogrammetry Technique to Survey Roadways for Accident Reconstruction
SAE World Congress & Exhibition2004 When reconstructing vehicle accidents, it is often important to record the accident scene roadway geometry. Survey techniques such as the plane surveying method1 and the coordinate and triangulation method2, have been the most widely used recording methods and are generally accepted in the industry. This paper proposes to introduce video tracking photogrammetry as a new tool in gathering accident scene and roadway data.
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- English
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