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Phase II Vehicle Dynamics Testing of Roadside Rock Liners

REPORT NUMBER

TRP-03-364-17

AUTHORS

Mojdeh Asadollahipajouh, John Reid, Cody Stolle, Ronald Faller

PUBLICATION DATE

2017-07-10

ABSTRACT

Roadside rock liners (i.e., rock ditch liners) are common erosion control features which may be comprised of large, angular rocks. Rock ditch liners were developed for areas susceptible to roadside erosion, such as silty soils and in conjunction with steep grades. The safe traversability of these features has not been studied. Wisconsin Department of Transportation (WisDOT) funded a research study to investigate the safe traversability of rock ditch liners. Vehicle stability was investigated using finite element analysis to simulate vehicular traversal over a rock ditch liner installed on level terrain. One non-compliant full-scale vehicle test was conducted with a small car (1100C) with a speed of 50 mph traversing over a level-terrain, replica rock ditch liner to obtain physical data, calibrate vehicle models, and investigate vehicle stability and damage. The small car experienced tire deflation at the end of the event and safely traversed over the rocks with minimal damage. The numerical simulation of an 1100C vehicle traversing a non-grade rock ditch liner was evaluated based on the test results. Further simulations were performed to identify critical scenarios for a vehicle traversing over a rock ditch liner installed on slopes. Simulation efforts consisted of small car and pickup truck tracking traversals over a 1V:3H fill slope at speeds of 30 and 45 mph with an encroachment angle of 15 degrees. No rollovers or snag were observed in simulations of small cars and pickup trucks traversing a non-grade rock liner, as well as a rock-lined, 3:1 slope. However, full-scale traversal testing under MASH is required to demonstrate vehicle stability and safety while traversing sloped-ditch liners. Also, additional research should be conducted to aid in the development of a safety guideline that includes maximum fill slope for a given speed and maximum rock size gradation, which assists engineers with configuring a safer roadside while minimizing roadside erosion.