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Evaluating the deceleration rate of air-braked heavy trucks based on brake components and their adjustment has been well documented for vehicles not equipped with anti-lock brake systems (ABS). Though there are many non-ABS trucks still on the road, ABS is becoming more common, having been required by NHTSA on all heavy trucks manufactured since March 1998. It has been found that the stopping-capabilities of ABS-equipped trucks are often not well modeled by the traditional Heusser technique. This paper will present an expansion of that method to accommodate ABS-equipped trucks, a means of characterizing air brake chambers to obviate the need for lookup tables, and discuss some sources of uncertainty in the analysis. A comparison of predicted stopping characteristics to test results for one truck is presented.

It has been shown that one can calculate the braking deceleration capabilities of an air-braked heavy truck given a modest amount of information about the components in the brake system and their adjustment level. The error introduced by ignoring the transient air pressure effects early in the event has been found to be negligible during stops from normal road speeds, but during stops from low speeds, the actual decelerations achieved can be expected to be lower than this overall average value. This paper presents an extension of the Heusser analysis technique to include the air pressure rise-time.

The critical speed model is a tool used by accident reconstructionists to determine vehicle speeds. One assumption implicit in the model is that when in a critical speed yaw, the vehicle's center of mass travels in a circular arc. The validity of this assumption was investigated by comparing the results obtained by manually measuring the tire marks, assuming them parallel to the center of mass path, and fitting a polynomial. The results indicate that the assumption of a circular path is reasonably accurate.

The most frequently cited papers on driver abilities are somewhat dated. This paper reports on the abilities of a large sample of drivers as they negotiated a closed cone-marked course using modern vehicles. The steering wheel position, brake line pressure, and throttle application were monitored, along with vehicle chassis accelerations. The objective of this paper is to report on the physical inputs utilized by operators, and compare gender-specific and vehicle-specific results. Willingness limits and g-g diagram results are presented.

Lightweight “drag sleds” have long been used by crash investigators to determine the “drag factor” at a crash scene. Despite this long history, no published work has ever shown a correlation between drag sled results and the skidding performance of vehicles on multiple “uncalibrated” surfaces. Indeed, some researchers have noted that their testing appeared to show a poor correlation between the two. It has become clear in recent years that the interaction between braking or skidding tires and pavement does not fit the simple weight- and speed-independent friction model that has been assumed, leaving the accuracy of drag sleds in doubt. This paper presents the results of several comparison tests at different locations, involving multiple skid-test vehicles, dozens of drag sleds of various designs, and more than a hundred “pullers,” and attempts to correlate the results of the two methods.

The most effective allocation of accident investigation resources requires knowledge of the overall uncertainty in a set of calculations based on the uncertainty of each variable in real-world accident analyses. Many of the methods currently available are simplistic, mathematically intractable, or highly computation-intensive. This paper presents the Finite Difference method, a numeric approach to partial differentiation with error analysis that requires no high-level mathematical ability to apply, uses very little computation time, provides good results, and can be used with analysis packages of any complexity. The Finite Difference method inherently incorporates an error treatment which provides investigators a basis to qualitatively rank from dominant to trivial the effects of uncertainty and errors in measured and estimated values.

Independent verification of the accuracy of data from Event Data Recorders (EDRs) is useful when using the information to help reconstruct a crash. To this end, the accuracy of the EDR function of the Airbag Control Module (ACM) was tested on 2010 and 2011 Toyota Camry sedans during straight line operation. During steady state operation, and maximum ABS-braking runs starting from approximately 80 km/h (50 mph), and 113 km/h (70 mph), non-deployment events were artificially induced to store event data. Following each run, the EDR was imaged using the Bosch Crash Data Retrieval (CDR) system. The CDR reported speed values were compared to Racelogic VBox differential GPS speed records. Data recorders were also used to monitor the vehicle Controller Area Network (CAN) bus traffic, including the indicated speed, brake pressure, engine RPM, and accelerator pedal position. The speed and RPM reporting algorithms stated in CDR Data Limitations were confirmed.

The evasive capabilities of motorcycles and riders are often an important consideration when analyzing a motorcycle crash. Specifically, the longitudinal distance or time required for a motorcycle to move laterally some distance can be of critical interest. Previous publications on this topic have not all measured the same thing and have often included limited test data so their results can be difficult to compare or apply. In addition to reviewing some of the literature on the topic, this paper will present the results of a series of tests conducted with four riders on four motorcycles swerving 2 m (6.5 ft) to their left after passing through a gate at speeds of 40 to 88 km/h (25 to 55 mi/h). The most recent testing involved relatively skilled riders who had faster transitions and greater willingness to lean than the “average” rider generally described in the literature.

A method for evaluating a driver's response in a nighttime crash scenario is offered. A pedestrian can be said to be within the headlight beam when the line representing the shape of a headlight beam equals the pedestrian approach vector. This method is based upon headlight beam mapping and the illumination necessary for drivers to recognize non-illuminated objects on an unlit road at night. The most notable information gained through this research is to be able to correlate headlight illumination with driver response distances. From 25 nighttime driver response distance experiments, information was gathered from many of the original authors. This information includes position left or right, headlight type, lighting, movement of the object or pedestrian, and the position (standing, slumped or laying).

It has been observed that locked-wheel skidding friction values are essentially vehicle- and tire-independent. It has been tacitly assumed by most crash reconstructionists that any ABS-equipped vehicle would also decelerate at nearly the same rate as any other ABS-equipped vehicle. This paper will review literature with relevant straight-line test results on paved roadways and gravel, and present additional results from recent tests generated with four modern vehicles built by three manufacturers. Results from the recent testing showed that locked-wheel skidding values on a concrete roadway were similar for all four vehicles, but the ABS-improvement on the same roadway varied. On gravel, ABS was always less effective than locked-wheel skidding. ABS and locked-wheel results on gravel had less car-to-car variation than tests conducted on concrete.

When performing calculations pertaining to the analysis of motor vehicle accidents, investigators must often select appropriate values for a number of parameters. The uncertainty of the final answers is a function of the uncertainty of each parameter involved in the calculation. This paper presents the results of recent tests conducted to obtain sample distributions of some common parameters, including measurements made with tapes, measurements made with roller-wheels, skidmark measurements, yawmark measurements, estimation of crush damage from photographs, and drag factors, that can be used to evaluate the uncertainty in an accident reconstruction analysis. The paper also reviews the distributions of some pertinent data reported by other researchers.

Monte Carlo analysis has been shown to be a powerful tool for evaluating confidence limits and probability distributions for values calculated during the analysis of vehicle accidents. Using this tool has generally required specialized software. This paper presents a method of using the tools provided with most simple spreadsheet programs to conduct Monte Carlo analysis with both evenly distributed and normally distributed variables for cases where the equations can be expressed in closed form. The accuracy one can expect given a particular number of trials is discussed. Example analyses using both even-probability and normal-probability variables are shown.

Eleven instrumented crash tests were performed as part of the 2016 World Reconstruction Exposition (WREX2016), using seven Harley-Davidson motorcycles and three automobiles. For all tests, the automobile was stationary while the motorcycle was delivered into the vehicle, while upright with tires rolling, at varying speeds. Seven tests were performed at speeds between 30 and 46 mph while four low-speed tests were performed to establish the onset of permanent motorcycle deformation. Data from these tests, and other published testing, was analyzed using available models to determine their accuracy when predicting the impact speed of Harley-Davidson motorcycles. The most accurate model was the Modified Eubanks set of equations introduced in 2009, producing errors with an average of 0.4 mph and a standard deviation (SD) of 4.8 mph.