title: Methodology for using advanced event data recorders to reconstruct vehicle trajectories for use in safety impact methodologies (SIM).
abstract: OBJECTIVE
  Safety impact methodologies (SIMs) have the goal of estimating safety benefits for proposed active safety systems. Because the precrash movements of vehicles involved in real-world crashes are often unknown, previous SIMs have taken the approach to reconstruct collisions from incomplete information sources, such as scaled scene diagrams and photographic evidence. The objective of this study is to introduce a novel methodology for reconstructing the precrash vehicle trajectories using data from advanced event data recorders (EDRs).
  
  
  METHODS
  Some EDRs from model year 2009 and newer Ford vehicles can record steering wheel angle in addition to precrash vehicle speed, accelerator pedal, and throttle input prior to the crash. A model was constructed using these precrash records and a vehicle model developed in the simulation software PreScan. The model was validated using the yaw rate and longitudinal and lateral accelerations also recorded by this type of Ford EDR but not used to develop the models.
  
  
  RESULTS
  In general, the model was able to approximate the dynamics recorded on the EDR. The model did not match the observed dynamics when either the vehicle departed the paved surface or when electronic stability control was active. Modifying the surface friction at the estimated point at which the vehicle departed the road produced better simulation results. The developed trajectories were used to simulate 2 road departure crashes, one into a fixed object and one into a vehicle traveling in the opposite direction, as if the departing vehicle were equipped with a lane departure warning (LDW) system. This example application demonstrates the utility of this method and its potential application to a SIM.
  
  
  CONCLUSIONS
  This study demonstrated a novel method for crash reconstruction that can be applied to a SIM for active safety systems. Benefits of this method are that the driver inputs do not need to be inferred from other reconstructions because they are recorded directly by the EDR. Currently, there are too few cases with the advanced EDR data to estimate fleet-wide benefits of a system. Because of recent regulation (49 CFR Part 563), EDRs are likely to be downloaded in more real-world crashes, making this method a potentially valuable and low-cost method for developing SIMs in the future.
authors.affiliation: Virginia Tech, Mechanical Engineering, Blacksburg, VA 24060, USA. Kdkusano@Vt.Edu
authors.forename: Kristofer D
authors.initials: KD
authors.lastname: Kusano
authors.forename: Rini
authors.initials: R
authors.lastname: Sherony
authors.forename: Hampton C
authors.initials: HC
authors.lastname: Gabler
mesh_terms: D000063:Accidents, Traffic / Q000706:statistics & numerical data*; D003198:Computer Simulation; D003625:Data Collection / Q000295:instrumentation / Q000379:methods*; D004867:Equipment Design; D005240:Feasibility Studies; D006801:Humans; D008962:Models, Theoretical; D018986:Motor Vehicles / Q000706:statistics & numerical data; D012449:Safety