McHenry Forum - Crash Reconstruction & Simulation

Q: References on Rollover speed versus the number of rotations?
A: The following is part of a literature review on Rollovers from our book, McHenry Accident Reconstruction:

• An often cited value for the average ground deceleration factor for rollovers is 0.40-0.65 and is based on reported values found in a 1972 report by Hight ( Reference 1 ).
  • It should be noted that the values reported were not measured values but were calculated from “estimated rollover speeds” based on “other road users’ statements, highway geometry, braking and centrifugal skid marks, critical cornering speeds, etc.”. However more recent measurements of drag on rolling vehicles support the general range of the estimates cited in the Hight report.
  Orlowski (Reference 2 ) included 8 dolly rollover tests wherein the average drag was found to be approximately 0.44 (see Figure below from Reference 2).
  • A few items to note: Dolly rollovers start with the CG elevated above the normal CG height (they sit upon the dolly and are launched) and the tests were run on level, paved terrain surfaces.
  Cooperrider, et al (Reference 3 ) includes soil-tripped, curb tripped and dolly rollover tests. The reported average deceleration from trip to rest was reported as: 0.48 g’s for soil tripped tests, 0.32 g’s for curb tripped tests and 0.31 g’s for the dolly rollover.
  • The authors of Reference 3 raise questions regarding the average decelerations during rollover that have been reported by others (e.g., References 1, 2, 4). However, the direct comparisons are made between averages over time (Reference 3) and averages over distance (References 1,2, 6). Clearly, the accident reconstructionist must work with the average deceleration over a distance.
  In 1998, Cooperrider further investigated soil tripped rollovers in Reference 4 . The results are similar to those found in Reference 3; The average drag (over distance) from start of furrow to rest was 0.80 (prior tests in Reference 3 showed 0.86 and 0.93).
  • Due to the nature of the soil trip area (they filled an area with dirt so no vegetation/furrow/irregular terrain effects were included). For their tests they had difficulty determining the end of trip phase/start of rollover.
  Some other references related to rollovers which should be reviewed are Moffatt (Reference 88 ) and Orlowski (Reference 6 ).

The following figure is from Orlowski, SAE 851734, Ref 2 below: REFERENCES

• 1 Hight, P.V., Siegel, A.W., Nahum, A.M., “Injury Mechanisms in Rollover Collisions”, SAE paper 720966
  2 Orlowski, K.F., Bundorf, R.T., Moffatt, E.A., ”Rollover Crash Tests – The Influence of Roof Strength on Injury Mechanics”, SAE 851734
  3 Cooperrider, N.K., Thomas, T.M, Hammoud, S.A., “Testing and Analysis of Vehicle Rollover Behavior”, SAE 900366
  4 Cooperrider, N.K., Hammoud, S.A., Colwell, J., “Characteristics of Soil-Tripped Rollovers”, SAE paper 980022
  5 Moffatt, E.A., “Occupant Motion in Rollover Collisions”, 19th Conference of AAAM
  6 Orlowski, K.R., Moffatt, E.A., Bundorf, R.T., Holcomb, M.P., “Reconstruction of Rollover Collisions”, SAE paper 890857