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2009 ARC-CSI Crash Conference Presentation
Accuracy of Critical Speed Formula (CSF) When Applied to Yaw Marks Leading to Rollovers of SUVs
Presented By: Lawrence Wilson, P.E.
Time: 1 hour
Yaw marks that lead to rollovers of SUVs are often measured by accident reconstructionsists and used to determine the speed of the subject vehicle by applying the critical speed formula (CSF). The results usually overestimate the speed of the SUV when compared to results derived from actual rollover testing.
An SUV will be instrumented to measure travel speed during steer maneuvers that will cause the vehicle to experience two‐wheel lift. Rollover will be presented through the use of outriggers. The yaw marks, pre‐outrigger contact, will be measured. The speed will be calculated using CSF and then compared with the measured speed of the SUV to determine the accuracy of CSF. The loading conditions will be tested:
- Driver only
- Fully Loaded (near GVWR)
- Fully Loaded (near GVWR) with loaded biased toward the rear to increase yaw rate
About Lawrence Wilson, P.E.
Principal Engineer and Accident Reconstructionist
Wilson Consulting, LLC, a nationally recognized forensic engineering firm specializing
in vehicle accident-related litigation, is lead by Lawrence A. Wilson, P.E.. Mr. Wilson
has over 15 years of experience in the field of accident reconstruction including expertise
in the following areas:
- Vehicle-to-vehicle collisions
- Airbag control module data analysis and deployment criteria
- Visibility, site distance, perception-reaction time
- Accident avoidance maneuvers
- SUV and light truck rollovers
- Commercial vehicle accident reconstruction
- Narrow object impacts
- Vehicle accident databases (NASS/CDS)
Mr. Wilson has extensive experience in accidents involving rollovers. This experience
includes:
- Steering-induced, on-road, untripped rollover tests of SUVs
- Publication of papers related to:
o Steering inputs that lead to rollovers
o Accident reconstruction techniques for rollover accidents
o Analysis of vehicle motion in rollover accidents
o Analysis of physical evidence and vehicle motion in rollover tests - Guest lecturer on rollovers at ARC-CSI Crash conference (2006, 2008)
- Development of graduate level curriculum related to rollover accidents at George Washington University's National Crash Analysis Center.
Mr. Wilson's crash test experience includes the following:
- Remote-controlled, steering-induced, on-road rollover tests
- Motorcycle-to-vehicle crash tests
- Vehicle-to-pedestrian crash tests
- Bus-to-vehicle crash tests
- Vehicle-to-vehicle crash tests
Mr. Wilson is a licensed Professional Engineer and a certified technician and data analyst
for the Bosch Crash Data Retrieval (CDR) system. He is also an active member of the
Society of Automotive Engineers (SAE) and the University of Maryland Chapter of the
Order of the Engineer.
