Friction Applications in Accident Reconstruction

Warner, Charles Y.; Smith, G. C. Moore; James, Michael B.; Germane, G.J.

doi:10.4271/830612

Cited by 43 publications

(12 citation statements)

References 5 publications

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“…Thus, the mailbox impact speed was computed to be 107.9 km/h. Because there was no evidence that the driver applied the brakes before impacting the mailbox, a drag factor of 0.01 for the rolling resistance was used (Warner et al 1983). The vehicle traveled a total of 8.7 m before impact for an estimated departure speed of 108 km/h.…”

Section: Reconstructed Variablesmentioning

confidence: 99%

Expansion of NASS/CDS for characterizing run-off-road crashes

Riexinger

Gabler

2020

Traffic Injury Prevention

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Objective: Runoff road (ROR) crashes account for one-third of all annual crash fatalities in the US. The National Automotive Sampling System Crashworthiness Data System (NASS/CDS) is a dataset which may be used to understand the nature of ROR crashes. Despite the wealth of coded data available in NASS/CDS, this dataset lacks coded information about the roadside environment and the off-road trajectory of the vehicle. This information would be useful for determining lane departure warning (LDW) benefits, residual safety problems, performance of current safety hardware, lane marking inventory, LDW test procedure development, radius of curvature characterization, and effectiveness of ESC. The purpose of this paper is to demonstrate a methodology for expanding the data available in NASS/CDS to form and validate a specialized road departure database. Methods: Observed, measured, and reconstructed data elements were extracted from NASS/CDS and compiled into the National Cooperative Highway Research Program (NCHRP) 17-43 database. Observed variables were primarily coded from the scene photographs and included information such as the lane markings, and geometry of the roadside cross-section. Additional variables were measured from the scaled scene diagrams including the path of the vehicle, road dimensions, and roadside object positions. The vehicle impact speed and departure speed were reconstructed using the WinSMASH delta-v, roadside object characteristics, and vehicle path. Two studies were conducted to demonstrate the usefulness of the NCHRP 17-43 database in evaluating both vehicle-based and infrastructure-based ROR countermeasures. Results: The resulting NCHRP 17-43 database includes 1,581 NASS/CDS cases representing 510,154 ROR crashes. Analysis of the database found that drivers which crashed following an overcorrection were younger than drivers which did not overcorrect. This may indicate that inexperienced drivers are more likely to overcorrect when departing the roadway. The 85 th percentile impact severity of ROR crashes, which occur on roads with a speed limit greater than 65 mph, is higher than the practical worst-case test conditions for roadside barriers. Conclusions: The NCHRP 17-43 database contains information extracted from NASS/CDS cases to better understand the nature of ROR crashes, driver behavior in these crashes, and the potential benefits of both vehicle-based and infrastructure-based ROR countermeasures.

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Section: Reconstructed Variablesmentioning

confidence: 99%

Expansion of NASS/CDS for characterizing run-off-road crashes

Riexinger

Gabler

2020

Traffic Injury Prevention

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“…The principle of the proposed trol system, etc.). To improve safety it would be more procedures consists in the use of an iterative process relevant to determine the causes of accidents (driver error, based on the minimization of quadratic error in order dysfunctions of the transportation system) [1,2]. The to find the optimal tyre characteristic.…”

Section: Subscriptsmentioning

confidence: 99%

Transversal tyre road characteristic estimation

Cadiou¹,

Hadri²

2004

Proceedings of the Institution of Mechanical Engineers, Part D:

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This paper presents two methods for lateral tyre/road characteristic identification. The proposed methods are estimation based on simulation (EBS) and estimation based on observer (EBO). The first method is based on the development of a vehicle dynamics simulation whereas the second is based on a vehicle dynamics observation. In the EBS method, a vehicle simulator is used to replay certain road tests assuming that only the side force characteristic is unknown. The EBO method uses an observer to reconstruct vehicle dynamics and thus estimate tyre forces. For both methods a tyre characteristic described by a reduced Bakker-Pacjeka tyre model is used to characterize the tyre/road interface. The principle of the proposed procedures consists in the use of an iterative process based on the minimization of quadratic error in order to find the optimal tyre characteristic. To evaluate the proposed procedures, some experimental results were performed. The results are obtained off line on the basis of a set of test data. The originality of these approaches is to have a simple method and a less expensive technique for the characterization of the tyre/road interface.

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“…µ y = µ x = µ. However, experimental data has shown that for tires, differences between these values do occur, [Warner, et al (1983)], so these coefficients are considered distinct. Following the above preliminary concepts, individual mathematical models for the longitudinal and transverse forces are discussed and presented.…”

Section: Longitudinal and Transverse Force Componentsmentioning

confidence: 99%

“…The approach taken here is to combine the individual longitudinal and transverse force component equations in such a way to produce a single force, F, tangent to the roadway surface where with components collinear with and perpendicular to the heading of the tire, and both in the road plane. It is instructional to begin the investigation of combined tire friction forces by looking at the concept referred to as the "friction circle" [see for example, Warner, et. al.…”

Section: Combined Longitudinal and Transverse Forcesmentioning

confidence: 99%

Modeling Combined Braking and Steering Tire Forces

Brach¹

2000

SAE Technical Paper Series

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The force distributed over the contact patch between a tire and a road surface is typically modeled in component form for dynamic simulations. The two components in the plane of the contact patch are the braking, or traction force, and the steering, or side or cornering force. A third force distributed over the contacts patch is the normal force, perpendicular to the road surface. The two tangential components in the plane of the road are usually modeled separately since they depend primarily on independent parameters, wheel slip and sideslip. Mathematical expressions found in the literature for each component include exponential functions, piecewise linear functions and the Bakker-Nyborg-Pacejka equations, among others. Because braking and steering frequently occur simultaneously and their resultant tangential force is limited by friction, the two components must be properly combined for a full range of the wheel slip and sideslip parameters. This paper examines the way in which these two components are combined for an existing approach known as the Nicolas-Comstock model. First, performance criteria for tire modeling are proposed. Then the Nicolas-Comstock model is examined relative to the criteria. As originally proposed, this model falls short of meeting the criteria over the full range of transverse and longitudinal wheel slip values and sideslip angles. A modified version of the Nicolas-Comstock model is presented that satisfies these performance criteria. Finally, comparisons are made of the Modified Nicolas-Comstock model to other combined tire force models and to existing tire force measurements.

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Friction Applications in Accident Reconstruction

Cited by 43 publications

References 5 publications

Expansion of NASS/CDS for characterizing run-off-road crashes

Expansion of NASS/CDS for characterizing run-off-road crashes

Transversal tyre road characteristic estimation

Modeling Combined Braking and Steering Tire Forces

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