Dr. Jennifer Schmidt
Dr. Ronald Faller
Dr. Cody Stolle
Date of this Version
Guardrail end terminals are often used to shield approach ends of roadside guardrail systems as well as protect errant motorists from the risk of rail penetration through the vehicle and/or rapid deceleration. Energy-absorbing end terminals absorb an errant vehicle’s kinetic energy through rail deformation, or other means, in order to safely decelerate the vehicle in a controlled manner. Most modern energy-absorbing terminals are proprietary, and few terminals have passed the safety evaluation criteria published in the American Association of State Highway and Transportation Officials (AASHTO’s) Manual for Assessing Safety Hardware (MASH) in order to be installed with the Midwest Guardrail System (MGS).
State Departments of Transportation (DOTs) are faced with a need to install energy-absorbing, guardrail end terminals that meet current MASH impact safety criteria. Thus, the Midwest Pooled Fund Program member states deemed it desirable to develop a new generic energy-absorbing guardrail end terminal. Thus, this Phase I study was conducted to perform preliminary analysis and design of a preferred concept or prototype. This initial effort included an investigation of patents and Federal Highway Administration (FHWA) eligibility letters to identify energy-absorbing terminals and their energy-absorption methods. Next, brainstorming was conducted to identify methods that could be used in a new terminal, after which preliminary design calculations and drawings were completed. Thereafter, several project paths and preliminary concepts were presented to the sponsor, followed by additional calculations and brainstorming. The final terminal prototype and its geometry was investigated and designed using results obtained through computer simulation using 3-D nonlinear finite element analysis software, LS-DYNA. This analysis included simulated impacts with end terminal hardware translating down a W-beam guardrail segment. A complete prototype drawing set was produced and submitted to local fabricators to obtain a cost quote, which revealed that the prototype was too complicated to fabricate and more expensive than desired. Finally, additional brainstorming and design refinement was performed using LS-DYNA, which was directed to simplify fabrication, reduce end terminal cost, and decrease the resistance force during translation along the rail. Conclusions were drawn, and recommendations were presented for continuing this work in a second phase.