The Roadside Safety Pooled Fund has prioritized their research needs for various hardware systems, including barrier deflections at lower impact severities. There is a need for State departments of transportation (DOTs) and other municipalities to have accurate deflection distances of barrier systems during a vehicular impact at a lower impact severity. Certain site conditions lower the likely impact severity of an errant vehicle, and therefore, DOTs need information regarding the barrier deflection at lower impact severities. It stands to reason that if an impacting vehicle hits the barrier system at a lower impact severity, then the barrier will deflect a shorter distance. Consequently, the Roadside Safety Pooled Fund has prioritized evaluating the deflection of common barrier systems at lower impact severities through computer simulation.

Objective

The primary objective of this study is to evaluate barrier deflections of common hardware systems at lower impact severities than the systems were originally crash tested. This effort will involve a state survey polling the Roadside Safety Pooled Fund members on which systems would be desirable for evaluation under this project. The TTI research team will then complete computer simulations to investigate the barrier deflections at lower impact severities.

Benefits

This project will benefit the members of the Roadside Safety Pooled Fund by providing a range of deflections for common barrier systems with lower than tested impact severities. This will provide members of the Roadside Safety Pooled Fund with additional tools when site constraints restrict deflection and impact severity.

Products

The TTI research team will provide barrier deflections of prioritized barrier systems for less than tested impact severities. This effort will be comprised of a state survey and computer simulation analyses. The TTI research team will prepare and submit a research report fully documenting the work completed within this project. This report will be submitted to the technical representatives of the Roadside Safety Pooled Fund for review and approval.

Work Plan

To meet the project objectives, the work plan for this phase will consist of four tasks as described below

Task 1: Literature Review and State Survey

The Task 1 objective is to review previous literature and testing related to barrier impacts with lower severities. The TTI research team will accomplish this review through various means, including use of internet search engines, as well as databases like the Roadside Safety Pooled Fund MASH database and the Midwest Roadside Safety Facility library of research projects. Additionally, the TTI research team will survey the members of the Roadside Safety Pooled Fund for needs related to barriers with reduced deflections and impact severities. In particular, the survey will request priorities of barrier types to investigate. This reviewed information will lay the foundation for the analyses in Task 2.

Task 2: Initial Computer Simulations
The TTI research team will first develop models of the barrier systems prioritized in the Task 1 state survey. Subsequently, the TTI research team will use the explicit finite element code LSDYNA (2) to perform initial impact simulations using the developed barrier models and currently available vehicle models. The TTI research team will compare these initial simulations to previous crash testing to ensure proper predictive capability. If needed, the TTI research team will make modifications to these models to improve predictive capability. Once the models’ predictive capability has been confirmed, the TTI research team will complete additional simulations of impacts with lower severities. This may include lower speeds, decreased angles, or a combination of both. The TTI research team will complete these simulations utilizing currently available MASH pickup truck models, which will provide a critical analysis on barrier deflection. Two barrier systems will be evaluated in this task. Each barrier’s dynamic deflection from the simulated pickup truck impact at lower severities will be documented.

 Task 3: Additional Computer Simulations
The objective of this task is to evaluate additional barrier systems through computer simulation, similar to Task 2. The TTI research team will evaluate two additional barrier systems under Task 3. The TTI research team will first develop models of the two additional barrier systems. Subsequently, the TTI research team will use the explicit finite element code LS-DYNA to perform initial impact simulations using the developed barrier models and currently available vehicle models. The TTI research team will compare these initial simulations to previous crash testing to ensure proper predictive capability. If needed, the TTI research team will make modifications to these models to improve predictive capability. Once the models’ predictive capability has been confirmed, the TTI research team will complete additional simulations of impacts with lower severities. This may include lower speeds, decreased angles, or a combination of both. These simulations will be completed utilizing currently available MASH pickup truck models, which will provide a critical analysis on barrier deflection. Each barrier’s dynamic deflection from the simulated pickup truck impact at lower severities will be documented.

Task 4: Reporting and Documentation T
his task includes the reporting and documentation of the project’s effort. The TTI research team will prepare and submit a research report fully documenting the work completed within this project. The TTI research team will submit this report to the technical representative of the Roadside Safety Pooled Fund for review and approval.

Time Schedule