Case Study
Dump Truck Rollover
Two vehicles, a loaded dump truck hauling 2B stone and a medium-sized SUV, were traveling parallel to one another in adjacent lanes when one vehicle exited its travel lane and entered the path of the other vehicle. The impact resulted in both vehicles losing control, exiting the roadway, and the dump truck and its contents rolling over on top of the SUV causing multiple fatalities. Reconstruction regarding which vehicle departed from their lane of travel was performed as well as an evaluation of the load condition of the dump truck and the operation of the commercial vehicle.
S-E-A was asked by the insurer of the construction company to conduct an accident reconstruction and evaluate the loading condition of the commercial vehicle.
S-E-A Diagram and Intermediate Vehicle Positions
Assigned Task:
To perform the analysis, S-E-A took the following steps:
- Created a scale diagram and 3D terrain from police terrestrial-based photos and drone aerial photos using photogrammetry.
- Performed inspections of the subject commercial vehicle to evaluate the maintenance condition, impact related damage, and the rated axle capacities.
- Performed a loading analysis of the subject commercial vehicle in an unloaded and loaded condition with the tag axle in both the raised and lowered configuration.
- Evaluated the loading procedure of the 2B stone including the weight distribution and load settling during the loading process.
- Conducted a road test of the subject commercial vehicle to evaluate how the 2B stone reacted/shifted/settled during different dynamic movements including, lateral accelerations experienced during low and high-speed cornering, longitudinal accelerations experienced while traversing inclines and declines, and vertical accelerations while experiencing roadway terrain and irregularities.
- Reconstruction calculations and computer simulations were completed to reconstruct the impact speeds, pre-impact motion, and collision dynamics of the subject vehicles.
Evidence was evaluated resulting in the following findings:
- The SUV departed from its lane of travel and impacted the front of the dump truck inducing a hard left steer which resulted in a loss of control and ultimately the rollover event.
- The loading procedure performed by the construction company resulted in a load that was evenly distributed along the floor of the dump bed container and formed a naturally occurring conical distributed load near the center of the dump bed.
- The axle weights of the subject dump truck in its accident loaded condition were below the axle ratings identified on the data plate of the dump truck.
- The road tests revealed that minimal load settling occurred during normal operation of the subject dump truck.
- The center of gravity of a uniformly distributed load versus the naturally occurring conical distributed load in the dump bed were negligibly different.
While painstaking research, engineering expertise and sophisticated lab equipment are key elements in reaching a sound scientific conclusion, the multi-disciplinary teams at S-E-A are a large part of the reason why we have been able to help so many clients find real answers. Our scientific methodologies cross all disciplines and our wealth of experience solving a wide range of problems is invaluable in assuring broad perspective and thinking unfettered by familiarity and repetition.
Loading Procedure Evaluation
Axle Load Evaluation
Evenly distributed load CG (blue) vs. accident loaded conditions CG (red)