Comparison of Roadside Crash Injury Metrics using Event Data Recorders

The occupant impact velocity (OIV) and acceleration severity index (ASI) are competing measures of crash severity used to assess occupant injury risk in full-scale crash tests involving roadside safety hardware, e.g. guardrail. Delta-V, or the maximum change in vehicle velocity, is the traditional metric of crash severity for real world crashes. This study compares the ability of the OIV, ASI, and delta-V to discriminate between serious and non-serious occupant injury in real world frontal collisions. Vehicle kinematics data from event data recorders (EDRs) were matched with detailed occupant injury information for 180 real world crashes. Cumulative probability of injury risk curves were generated using binary logistic regression for belted and unbelted data subsets. By comparing the available fit statistics and performing a separate ROC curve analysis, the more computationally intensive OIV and ASI were found to offer no significant predictive advantage over the simpler delta-V.

A Framework for the Automation of Discrete-Event Simulation Experiments

Simulation is an important resource for researchers in diverse fields. However, many researchers have found flaws in the methodology of published simulation studies and have described the state of the simulation community as being in a crisis of credibility. This work describes the project of the Simulation Automation Framework for Experiments (SAFE), which addresses the issues that undermine credibility by automating the workflow in the execution of simulation studies. Automation reduces the number of opportunities for users to introduce error in the scientific process thereby improvingthe credibility of the final results. Automation also eases the job of simulation users and allows them to focus on the design of models and the analysis of results rather than on the complexities of the workflow.

Catastrophic Flooding In North-Central Pennsylvania: Geomorphic Findings From The September 2011 Event And Their Significance To

Tropical Storm Lee produced 25-36 cm of rainfall in north-central Pennsylvania on September 4th through 8th of 2011. Loyalsock Creek, Muncy Creek, and Fishing Creek experienced catastrophic flooding resulting in new channel formation, bank erosion, scour of chutes, deposition/reworking of point bars and chute bars, and reactivation of the floodplain. This study was created to investigate aspects of both geomorphology and sedimentology by studying the well-exposed gravel deposits left by the flood, before these features are removed by humans or covered by vegetation. By recording the composition of gravel bars in the study area and creating lithofacies models, it is possible to understand the 2011 flooding. Surficial clasts on gravel bars are imbricated, but the lack of imbrication and high matrix content of sediments at depth suggests that surface imbrication of the largest clasts took place during hyperconcentrated flow (40-70% sediment concentration). The imbricated clasts on the surface are the largest observed within the bars. The lithofacies recorded are atypical for mixed-load stream lithofacies and more similar to glacial outburst flood lithofacies. This paper suggests that the accepted lithofacies model for mixed-load streams with gravel bedload may not always be useful for interpreting depositional systems. A flume study, which attempted to duplicate the stratigraphy recorded in the field, was run in order to better understand hyperconcentrated flows in the study area. Results from the study in the Bucknell Geology Flume Laboratory indicate that surficial imbrication is possible in hyperconcentrated conditions. After flooding the flume to entrain large amounts of sand and gravel, deposition of surficially imbricated gravel with massive or upward coarsening sedimentology occurred. Imbrication was not observed at depth. These experimental flume deposits support our interpretation of the lithofacies discovered in the field. The sizes of surficial gravel bar clasts show clear differences between chute and point bars. On point bars, gravels fine with increasing distance from the channel. Fining also occurs at the downstream end of point bars. In chute deposits, dramatic fining occurs down the axis of the chute, and lateral grain sizes are nearly uniform. Measuring the largest grain size of sandstone clasts at 8-11 kilometer intervals on each river reveals anomalies in the downstream fining trends. Gravel inputs from bedrock outcrops, tributaries, and erosion of Pleistocene outwash terraces may explain observed variations in grain size along streams either incised into the Appalachian Plateau or located near the Wisconsinan glacial boundary. Atomic Mass Spectrometry (AMS) radiocarbon dating of sediment from recently scoured features on Muncy Creek and Loyalsock Creek returned respective ages of 500 BP and 2490 BP. These dates suggest that the recurrence interval of the 2011 flooding may be several hundred to several thousand years. This geomorphic interval of recurrence is much longer then the 120 year interval calculated by the USGS using historical stream gauge records.