ollision C The International Compendium for Crash Research
Volume 12 Issue 1
Autonomous Vehicle Technology
an Accident Reconstructionist’s Perspective
Fracture Energy Calculations for Wooden Utility Poles
Tire Friction Comparisons in Various Temperature
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Contents
Volume 12 Issue 1
inside 4
Industry Partners
6
Letter From the Editor
5
8
Advertiser Index and Digital Download Information
features 8
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62 74
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Three Different Methodologies for Determining the Drag Factor for Motorcycles Sliding on Their Sides
by Michael DiTallo, Brent Munyon, Thomas Green, Eric Paul, Kelley Adamson, Mike Merolli, Kevin Vosburgh, Billy Cox, Robert Anderson, David Hallman, Eric Moody, and James Whelan
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Tire Friction Comparison of Three Tire Types in Warm and Near Freezing Temperatures by Peter J. Leiss, Steven Becker and Gary Derian
My Turn at the Wheel: A Dirty Trick to Achieve the Desired Result, or What? by Erik Carlsson
Motorcycle Center of Gravity Data: Methodology and Reference
by Michael DiTallo, Eric Paul, Kelley Adamson, Thomas Green, Mike Merolli, Brent Munyon, Kevin Vosburgh, Billy Cox, Eric Moody, Robert Anderson, James Whelan and David Hallman
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Fracture Energy Calculations for Wooden Utility Poles by Nathan Rose
Autonomous Vehicle Technology: Looking One, Five, and Fifteen Years into the Future. An Accident Reconstructionist's Perspective by Luis Flores
3D Laser Scanners in Crash Testing by Thomas Green, Michael DiTallo, Eric Paul, Kelley Adamson, Mike Merolli, Brent Munyon, Kevin Vosburgh, Billy Cox, Robert Anderson, David Hallman, Eric Moody and James Whelan Fast Approach to Building Solid Cases: Laser Scanning Provides Important Benefits for Investigator
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by Chad McFadden
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Evaluation of the MIDE Slam Stick as a Low-Cost Accelerometer and Data Acquisition System for Vehicle Skid Testing
by David Hallman, Robert Anderson, Billy Cox, Kevin Vosburgh, Kelley Adamson, Thomas Green, Mike Merolli, Brent Munyon, Eric Paul, Eric Moody, James Whelan, and Michael DiTallo www.collisionpublishing.com
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Different Methodologies for Determining the Drag Factor for Motorcycles Sliding on Their Sides
Michael DiTallo, Brent Munyon, Thomas Green, Eric Paul, Kelley Adamson, Mike Merolli, Kevin Vosburgh, Billy S. Cox, Jr., Robert Anderson, David Hallman, Eric Moody, James Whelan 8 Collision Magazine - Volume 12 Issue 1
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ntroduction Twenty-six motorcycles were used to conduct tests to determine the drag factor for a motorcycle sliding on its side. Three different methodologies were employed for the testing. The motorcycles in the first test method were already on their sides before they were pulled across the pavement. For the last two test methods, the motorcycles fell to the pavement before sliding. otorcycles The test motorcycles consisted of various ages, styles and manufacturers. The manufacturers included; Harley Davidson, Buell, Honda, Kawasaki, Suzuki, Yamaha, Jonway and Znen. Motorcycle styles included sport, touring, motocross and moped. Photograph 1 shows some of the motorcycles used for the tests. Many of the tested motorcycles had been involved in previous impact testing at the 2016 ARC-CSI earlier in the year. The test motorcycles had standard equipment with some of them having minor pre-testing modifications such as the removal of the seat. One of the sport style test motorcycles had frame sliders. Any modifications were minor in nature and would have no outcome on the results of the drag factor testing. Each motorcycle was assigned a letter destination for the testing. Figure 1 shows the letter designation, brand, model, VIN, year, and type for each tested motorcycle.
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est Methodology The first test method used a load cell to measure the force required to drag the motorcycles across the pavement (pull tests). The tests consisted of dragging the motorcycle in either longitudinal or lateral pull configurations. A second method used the drop method which involves releasing a motorcycle from rear hydraulic lift of a moving box truck (drop tests). When the box truck reached a target speed, the motorcycle was released from the lift of the truck, allowing the motorcycle to drop and slide to rest. The final testing method involved towing a motorcycle behind a moving vehicle with its front tire held in a pneumatic clamp just above the pavement; the front tire was mechanically locked into a stationary position; the tow vehicle gained speed; and the front wheel was released from the pneumatic clamp allowing the motorcycle to drop, slide and/or tumble to rest (clamp test).
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Tire Friction Comparison of Three Tire Types in Warm and
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he purpose of this paper is to demonstrate the differences in braking capability of different types of tires through data collected from testing. Testing was performed during summer weather near 75°F (24°C), and then again on the same road surface in winter with temperatures near freezing (32°F, 0°C). The main variable in these tests was the type of tire installed. Three different tire types; summer, all season, and winter, all of the same size, were tested in ambient temperature on wet and dry asphalt surface with a single vehicle. The braking tests were conducted with ABS activated and deactivated for modulated and locked wheel friction comparison of the tire types.
fort braking performance, whether locked wheel or ABS modulated, is influenced mainly by the road to tire interaction and is greatly affected by the tire tread and material. This paper researches the difference in braking performance of 3 different tires; 3 season, all season, and winter of the same size in two ambient temperatures on a single wet and dry asphalt surface with a single vehicle. The braking tests were conducted with ABS active and deactivated for modulated and locked wheel friction comparison of the tire types.
High performance, “3-season”, tires are increasingly available as Original Equipment ManufacAccident reconstructionists rely on accurate fric- turer fitment. These tires were once reserved for tion coefficients to calculate speeds from skid and sports cars and European performance sedans. yaw marks left at a collision scene. Maximum ef- Today they are available as standard or option24 Collision Magazine - Volume 12 Issue 1
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Peter J. Leiss Steven Becker Robson Forensic Inc.
Gary Derian
Derian Engineering
Near Freezing Temperatures al equipment on domestic Sport Utility Vehicles and compact cars. These tires are not intended to be used when temperatures are near freezing or on snow and ice, necessitating the use of either all-season or winter tires for owners in areas that are susceptible to these atmospheric conditions. Similarly, winter tires are not intended to be used during warm weather, but drivers may travel to warmer areas or leave their winter tires on during warm conditions.
A total of 144 tests were conducted on both wet and dry pavement conditions.
The vehicle chosen for this testing is available from the manufacturer with either all-season or 3 season tires. The vehicle was left in an as manufactured condition for all tests, with the exception of tire changes and deactivating the Anti-Lock Brake System/Electronic Stability Control Electro-Hydraulic Control Unit for locked wheel tests. The vehicle was braked from about 45 MPH for all tests.
Guidance will be given for modifying the friction coefficient used in reconstruction calculations for the permutations of tires, brake systems, roadway conditions, and ambient temperatures. The results show differences not only between the tire types, but how each tire types’ friction varies between wet and dry asphalt and ABS modulated and locked wheel braking, in moderate and cold climates.
The results show differences not only between the tire types, but how each tire types’ friction varies between wet and dry asphalt, and temperature. The results also report tire friction values higher than typical published numbers. Results of the near freezing testing are compared to results of testing in warm temperatures.
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eel h W The t a rn u T My
A DIRTY TRICK TO ACHIEVE THE DESIRED RESULT, OR WHAT? erik carlsson
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his article is about a traffic accident that perhaps can be de-scribed as more unnecessary than most accidents, if indeed it is even possible to rate different levels of something unnecessary. The tiny driver of a small car, equipped with the then recently mandated air-bag in the steering wheel, was southbound on a four-lane two-way ma-jor highway, traveling at a moderate speed in the ‘slow’ lane. Her mind may have been somewhere else because she did not notice that a traffic signal at an intersection in front of her on the straight road turned red. First when an SUV that was stopped at her right on the intersecting country road began to move forward did she realize she had a red light. She hit the brakes, and almost managed to stop before her car reached the intersection. The driver of the SUV was making a left turn, and, as many drivers do, cut the corner. He began his northbound turn as soon as the front of his SUV began to cross the first of the two southbound lanes. The ensuing collision happened in that lane.1 The impact was minor, and can perhaps best be described as a sideswipe, with the left front corner of the car hitting the driver side rear half of the now northbound SUV. Both vehicles could have been driven from the accident scene, but the airbag in the car deployed and broke the tiny driver’s wrists. She therefore ended up in a hospital instead of driving her car home. The driver of the car admitted at the subsequent police investigation that she didn’t see the traffic light turning red and that she only became aware of the red signal when she saw the SUV beginning to move. The driver of the SUV stated that he didn’t see the approaching car until just before the collision. He had been waiting for a green light and was concentrating on the traffic signal. When the light turned green, he “stepped on it” and began his left turn. He had no reason to look out for traffic on the highway because he knew that drivers on the highway had a red light when he got green light. Overly aggressive airbags! It did not take long after that the mandatory requirements for airbags in the steering wheels in new cars went into effect before it became clear that the airbags were too powerful, or “overly aggressive,” as NHTSA phrased it. The airbags caused in low speed impacts more injuries than they prevented. The reason for the high force with which the airbags deployed was that it was initially believed that for optimal protection of drivers the vehicles should meet the mandatory FMVSS 208 frontal barrier crash test requirements with the driver dummy unrestrained. The airbags therefore had to be more powerful than they needed to be if the vehicles instead were tested with the dummies restrained. De-powered airbags: The observation that the airbags in low speed impacts caused unnecessary injuries led to a changed safety standard that resulted in less powerful airbags. These airbags were in the beginning called “de-powered airbags.” Owners of cars equipped with the overly aggressive airbags were in some cases permitted to have the airbags disconnected. Broken wrists led to a law suit. The lady driver’s injuries became a text book example of unnecessary injuries caused by overly powerful airbags. She would probably have escaped injuries completely if the airbag had not deployed as this was a collision that even in the pre-seatbelt and pre-airbag era no doubt would have been considered an insignificant fender-bender.
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Motorcycle Center of Gravity DatA Methodology and Reference
2016 ARC-CSI Motorcycle Crash Team Pre-Crash Testing Michael DiTallo Eric Paul Kelley Adamson Thomas Green Mike Merolli Brent Munyon Kevin Vosburgh Billy S. Cox, Jr. Eric Moody Robert Anderson James Whelan David Hallman
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bstract Over the course of several days before the 2016 ARC-CSI crash conference, the Motorcycle Crash Team conducted detailed inspections and measurements of the test motorcycles. The test motorcycles included five new Harley-Davidson Inc., (Harley-Davidson) motorcycles, which were owned and driven by Harley-Davidson, but were never involved in collisions. The remainder of the test motorcycles had all been involved in some type of collision or event resulting in minimal side damage. None of the test motorcycles previously involved in a collision had sustained frontal damage. The test motorcycles were photographed, manually measured, scanned using a FARO 3D scanner (See scanner usages in Crash Testing Article Volume 12 Issue 1), and the damage and configuration of each
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one was documented. All test motorcycles were measured and weighed “wet” (full gas tank) and several were also measured and weighed “dry” (empty gas tank). One inspection goal was to create a resource containing the longitudinal and vertical center of gravity (CG) for each test motorcycle that could become a useful database in crash reconstruction analysis.
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ntroduction The same process and methodology of data collection was utilized for all twenty-six motorcycles. The following will describe and illustrate the process of collecting data to determine the center of gravity for Test Motorcycle A as the example. Test Motorcycle A is a 2006 Harley-Davidson Sportster.
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ethods and Materials The test motorcycles’ gasoline tanks were filled with fuel and the engine oil levels were checked to ensure they were “full.” The motorcycle dimensional data was measured and documented including the static weight without an operator. The tire air inflation pressure was checked and filled to recommended pressure. In all cases the front tire was lifted as high as possible to be between 25 to 45 degrees from level. The hoisted weight on the rear tire was documented as well as the hoisted height of the front axle. The data was corrected for the height of the scale pads. The scales used were a set of Intercomp SW-RFX 1500 wireless PC scale system, which were calibrated, and a certified accuracy to +/- 0.1% of applied load or +/- graduation, whichever is greater.
Once the data was collected the longitudinal and vertical center of gravity was analyzed. We always lifted the front tire, however either the front or the rear tire could have been lifted for this analysis.
Figure 2: Static weight of Test Motorcycle A
Figure 1: Test Motorcycle A being weighed
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Fracture Energy Calculations for Wooden Utility Poles Nathan Rose
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Kineticorp, LLC.
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ntroduction
The following mechanisms of energy dissipation may need to be considered when calculating the initial speed of a vehicle that impacted a wooden utility pole: (1) crushing of the vehicle; (2) full or partial fracture of the pole; (3) moving and tilting of the pole within the ground; (4) acceleration of the pole after a full fracture; and (5) tire, and other dragging forces, acting on the vehicle during its post-impact motion [Daily, 2009; Cofone, 2007 and 2012].i Each of these will be discussed in this article. However, the focus will be on validating Kent and Strothers’ method for calculating the full or partial fracture energy for the pole [1998]. In general, a vehicle’s kinetic energy at the time of impact with a wooden utility pole can be calculated by adding the vehicle’s post impact kinetic energy to the energies dissipated through vehicle crush, pole fracture, and pole movement (including tilting and accelerating after fracture). This is described mathematically by Equation (1).
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Autonomous Vehicle Technology Looking One, Five, and Fifteen Years into The Future
An Accident Reconstructionist's Perspective
Luis Flores P.E., ACTAR, CFEI Crane Engineering
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ntroduction I recall a friend of mine asking me about a year ago if I was worried about autonomous vehicles making my job as a vehicle accident investigator essentially obsolete. I retorted: as long as it’s still humans behind the software, there will always be room for, well, human error.
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unctionality As you can imagine, the proliferation of autonomous vehicle technology relies on more than the safety mechanisms introduced by vehicle manufacturers can offer. More importantly, a coordinated effort amongst traffic engineers and the general public is key to its success. Autonomous vehicle technology operates on the idea that vehicles will be able to: “talk to” or “see” each other; interact with the ever-changing infrastructure they operate on; and account for the non-motorized traffic they encounter (pedestrians, bicycles, wildlife, etc.). Radar and Light Detection and Ranging (LiDAR) technologies sense objects near and far, GPS keeps the vehicle on its route, and computer vision (optics) detect markings and signs along the road.
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evel Up The Society of Automotive Engineers currently identifies six levels of vehicle automation:
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Level 0 is no automation.
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Level 1 is driver assistance (i.e. electronic stability control and adaptive cruise control).
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Level 2 is partial automation (i.e. driver can deactivate automated accelerating, braking and steering and take over).
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Level 3 is conditional automation (i.e. autonomous in limited environments such as freeways).
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Level 4 is high automation (i.e. all environments except severe weather).
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Level 5 is full automation.
xisting Limitations Perhaps the most overlooked item on the autonomous feasibility checklist is cybersecurity. Just last year, WIRED magazine published a story on how a pair of cybersecurity researchers managed to take control of a Jeep Cherokee from its climate control to its audio system. And this year that same pair demonstrated a slew of new attacks perpetrated through the vehicle’s communication network, or CAN bus. It is no coincidence that shortcomings like this one have resulted in a senatorial plan to introduce an automotive security bill in 2015, legislation that would direct the National Highway Traffic Safety Administration (NHTSA) and the Federal Trade Commission (FTC) to establish federal standards to secure personal cars and protect drivers’ privacy.1
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3D Laser Scanners in Crash Testing
Thomas Green Michael DiTallo Eric Paul Kelley Adamson Mike Merolli Brent Munyon Kevin Vosburgh Billy S. Cox, Jr. Robert Anderson David Hallman Eric Moody James Whelan
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bstract A series of motorcycle crash tests was conducted at the 2016 ARCCSI Conference. The crash plan was aggressive, with 27 separate crash tests performed over 3 days. One day of crash testing was open to attendees of the conference. Accurate and efficient data collection was a necessity. A decision was made to use several 3D laser scanners simultaneously during the physical measurement process of the crash tests. The FARO S-120 and FARO X-330 3D scanners were used for these tests.
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ntroduction During the 2016 ARC-CSI Conference, a large group of motorcycle crash tests was performed. An article published in the February 2017 issue of Collision Magazine entitled “Motorcycle Crash Testing: Advanced Boot Camp Was Born” describes the crash testing process and lists the motorcycles used during the testing. Other aspects of the testing pro-
cess and data acquisition results are described in another article in this issue of Collision Magazine. See “Evaluation of the MIDE Slam Stick X As a Low Cost Accelerometer And Data Acquisition System For Vehicle Crash Testing.” The motorcycle crash testing included motorcycle-to-barrier, motorcycle-tostationary vehicle and motorcycle-to-moving vehicle impacts.
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ethods and Materials To ensure the results of any testing are useful, reliable, and repeatable, certain testing parameters must be accurately measured and recorded. For our crash testing, these parameters included vehicle weight, vehicle dimensions (pre and post-crash), vehicle positioning (pre and post-crash), impact speed and crash acceleration. During these motorcycle crash tests, we used the following instrumentation and equipment: custom MIDE Slam Sticks and IST 3-D 6-degree of freedom accelerometers to measure the crash pulse; Intercomp SW-RFX 1500 racing scales to measure vehicle weights; FarmTek Polaris timer, V-Box Sport and Garmin VIRB to measure vehicle impact speeds; high-speed and regular digital video cameras to record the tests, and total stations and 3D scanners to measure physical dimensions.
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FAST APPROACH TO BUILDING SOLID CASES
LASER SCANNING PROVIDES IMPORTANT BENEFITS FOR INVESTIGATORS Chad McFadden
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Trimble od Green has been doing accident and crime scene reconstructions for 14 years. In addition to collecting and analyzing information, Green is working to improve the reconstruction process on-scene and in the office. His work is drawing attention in Washington and surrounding states.
A 21-year veteran with the Washington State Patrol (WSP), Green is using his experience and knowledge to simplify and speed the work in collecting and analyzing information and evidence at accidents and crime scenes. Green’s blend of high-tech hardware and software tools together with common sense approaches has produced measureable improvements in scene reconstruction. Like many law enforcement agencies, WSP has adopted laser scanning as a tool for scene measurement and documentation; Green has spearheaded the move. He has worked on every aspect of scene reconstruction, from data collection and processing to the production of drawings. But, for Green and others, the technology takes a back seat to the core mission of public safety and law enforcement. “I’m not so concerned with how pretty the point cloud looks as I am with getting the details—all of the details—to accurately gather measurements of the scene for reconstruction,” Green said. Green believes that laser scanners’ ability to gather vast amounts of information can play an important part in producing reports, drawings and exhibits that contribute to the successful resolution or prosecution of a case. But for scanners to become mainstream tools, they must seamlessly blend into the work of people who are already very, very busy.
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ime, Safety and Comprehensive Data
On-scene investigators at fatal collisions and crime scenes face a variety of challenges. They must collect comprehensive information in an accurate, systematic manner. Often working at night or in bad weather, investigators need to capture data quickly while the scene is fresh and before rain or snow can cause evidence to erode or wash away. Speed is also essential to reduce the duration of road or lane closures, which are costly and inconvenient to the public. According to a 2015 report by the National Highway Transportation Safety Administration (NHTSA), costs attributed to congestion caused by fatal crashes in 2010 including travel delay, excess fuel consumption, greenhouse gases and pollutants totaled $189 million. On average, a fatal collision resulted in a closure of nearly 3.75 hours. By using laser scanners for data collection, Green and his WSP colleagues demonstrated that they could reduce the time on site while significantly increasing the quality and quantity of information they gather. Collision investigators must also guard their own safety. In many incidents, they are working near traffic or other hazards. Other measurement methods such as total stations and baseline-and-offset
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techniques may require several people to capture and record the data and can result in closing more lanes. Total station measurement often requires someone else at the site to hold the prism rod; that person could be working on some other aspect of the investigation.
But large point clouds come with their own challenges. “There are people who look at a point cloud and say they can’t see the details,” Green said. “That is usually because it wasn’t scanned or processed correctly. We want to avoid the trap of not seeing the evidence for the cloud. We do not want just a huge cloud; we want better manageGreen knows of some jurisdictions that have ment of the cloud.” The solution comes from inclosed busy street or arterial for 6 hours or more tegrating the processes from collection through to to accommodate measurements with a total sta- final reports. tion. In contrast, a laser scanner, which operates autonomously, can reduce the time and number That integration begins in the field, where WSP of people needed for measurement and documen- uses a Trimble TX5 scanner. The scanner simplitation while also lessening exposure to traffic. fies the work for scene investigators by providing preset scanning modes that capture data at differIt’s not just the work in the field. In addition to ent levels of resolution. Similar to preset modes on-scene measurements, reconstructors must also on a digital camera, users can select the scanning manage and process the data to produce the in- mode to fit the detail needed at each setup on the formation needed by investigators and district site. Green has developed guidelines for WSP inattorneys. They need to focus on the pertinent vestigators that suggest which mode is appropridetails while maintaining data integrity and the ate for capturing different types of details and evichain of evidence. Their finished products are ex- dence. “We like the presets,” he said, “because we hibits, reports and analyses that provide the basis can teach our people what mode to use in a given for the accurate depiction of the scene and events. situation without having to calculate resolution.” Green has developed a combination of hardware, Scanning at higher resolution requires a bit more field procedures, software and data management time but can capture small details. “I might need that reduces time on site and yields greater depth to capture shell casings or faint tire marks; for of detail throughout an investigation. that we might scan at high-resolutions,” Green explained. “But for other setups we can run at orensic Scanning: Focus on Evidence To some degree, scanners have been uti- lower resolution, which is much faster. We can lized in scene reconstruction for nearly 20 gain a lot more detail much faster, by as much as years. A scanner uses laser technology to 2/3rds than with other scanners.” collect a large number of closely-spaced measure- When data from the scanner arrives in the ofments and produce a “point cloud” of 3D points. fice, detectives use Trimble RealWorks software By setting the scanner in several locations around to combine the scans and begin analyzing the a scene, investigators can capture multiple point scenes. The software can use “plane-based” and clouds to develop a 3D snapshot of the location. “cloud to cloud“ registration to merge multiple Even small or subtle features such as shell casings scans—the technique helps reduce the need for or tire marks can be captured using the scanner on-scene investigators to handle the spherical tarand point cloud. gets commonly used in many scanning projects.
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After the on-scene work is complete, the scan data is transferred to office computers for archival and processing. The multiple scans are combined into a single point cloud, which provides a complete view of the scene.
Although target spheres are needed in some situations, Green said the plane-based and cloud to cloud approach is much simpler and faster for field investigators—so much so, it’s become the default method.
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