Computer Simulation of Pavement Edge Traversal

This study examines through computer simulation the vehicle dynamics regime of vehicle entry into a travel lane via traversal of a vertical change in pavement elevation. A three-dimensional vehicle dynamics software package is used to model a vehicle as a six degree-of-freedom sprung mass with up to five degrees-of-freedom for each unsprung mass for each axle. The parameters of the simulator’s radial and sidewall tire force models are determined through correlation with full-scale vehicle traversal tests.

The correlation parameters include vehicle speed, heading, yaw rate and lateral acceleration. The simulation is first calibrated by successfully modeling vehicle traversal of a pavement edge at shallow angles. The calibrated model is then used to analyze vehicle yaw motion for the condition when the direction of travel of the vehicle is parallel to the pavement edge while the tires on the edge side of the vehicle scrub against the pavement edge prior to the vehicle mounting the pavement. The study further uses the calibrated model to examine the relationship between pavement edge height and the vehicle speed and encounter angle required for the vehicle to mount a pavement edge without steer input.

The simulation output matches the test data to a reasonable degree in the shallow angle runs and in the tire scrub run. A previously-published empirical relation between pavement edge height and vehicle closing speed required to climb the pavement edge is mirrored by the simulations results. The simulation model predicts slightly higher normal closing speeds to initiate edge climb than in the published relation.