BACKGROUND
    Adequate storm water drainage is necessary to prevent vehicular hydroplaning on bridges and roadways. WSDOT has developed a single slope concrete median barrier that provides drainage to scupper openings located at the base of each barrier segment. This barrier is planned for use on high speed roadways where drainage of the pavement surface is needed.

OBJECTIVE
    The objective of this project will be to develop a single slope concrete median barrier with a pin and loop connection and drainage slots for pavement and roadway drainage to scupper inlets that meets the crash performance specifications of MASH for TL-3 impact conditions.

BENEFITS
    This project will provide WSDOT with a viable concrete median barrier option that provides drainage to scuppers as well as satisfies the crash performance requirements of MASH for TL-3 impact conditions.

 
PRODUCTS
    Texas Transportation Institute (TTI) will perform engineering analyses of the proposed concrete median barrier and develop detailed drawings of the barrier segment and components. TTI will then perform computer modeling and simulation using LS DYNA to predict the performance of the barrier system with respect to MASH TL-3 evaluation criteria. TTI will provide a report that contains detailed drawings of the barrier system tested, material specifications of all components used in the test installation, as well as detailed information and data obtained from the crash tests. A summary of the engineering analyses, computer modeling and simulation effort performed for this project will also be provided in the final report. A copy of the final report will be provided in electronic format for distribution to each participating member state.

IMPLEMENTATION
    A single slope concrete barrier with pin and loop connection and drainage slots will be developed for this project. If the testing is successful, the design can be implemented through the development of a standard detail sheet based on drawings developed under this project.

WORK PLAN
Task 1 -- Engineering of Barrier Segment and Components
    As part of this task, the researchers will review the design details of the proposed WSDOT Pin and Loop barrier. Detailed strength analyses will be performed to determine the appropriate reinforcing steel details for the barrier segments. Strength analyses will be performed on the pin and loop connection to determine if the connection and components are adequate to resist the forces generated in a design impact with a pickup truck.

Task 2 -- Simulation Analysis of the Concrete Barrier
    In this task, the researchers will perform finite element (FE) analysis to evaluate the performance of the concrete barrier under MASH TL-3 impact conditions. The simulation analysis will be used to determine the expected maximum barrier deflection and to evaluate vehicular stability. The analysis will also be used to determine if the scupper geometry has any potential of causing wheel snagging during an impact with a small passenger car. Wheel snagging can cause higher occupant compartment deformation and greater vehicular instability.
    A commercially available general-purpose finite element analysis software, LS-DYNA, will be used to perform the detailed FE analysis. LS-DYNA is an explicit nonlinear finite element program that is capable of simulating complex nonlinear dynamic impact problems. It is frequently used in the roadside safety community for analyzing roadside safety hardware performance under impact loading. LS-DYNA incorporates state-of-the-art contact algorithms that can be used to model vehicular collisions with roadside objects.
    The FE model of the barrier segments will be developed using solid elements. The segments will be modeled using mostly rigid material representation. The faces of the barrier segments, where they come in contact with adjacent segments, and the bottom of the barrier, where it contacts the ground, will be modeled with elastic material representation. The pin-and-loop connections between adjacent barrier segments will be modeled using elastic-plastic material representation. Thus, the connections will be able to deform in an elastic-plastic manner on vehicular impact. Due to the lack of a fast and robust concrete material model, the failure of concrete will not be incorporated in the model. This will also reduce the time and cost required to model the barrier system, and the CPU time taken to complete the simulations.
    The researchers will develop a 150-ft long barrier installation model, which will be comprised of 12 barrier segments. Once the barrier system model has been developed, a vehicle impact simulation will be performed using a pickup truck model. The researchers will use the 2270P (5000-lb) Chevrolet Silverado pickup truck model recently developed by the National Crash Analysis Center (NCAC). The pickup truck will impact the barrier at a speed of 62 mi/h and an angle of 25 degrees, as required by the MASH criteria. The impact will take place 4 ft upstream of the connection at the one-third point of the 150-ft barrier system model.
    The objective of this simulation will be to determine the expected maximum lateral deflection of the barrier and to evaluate vehicular stability. It should be noted that the maximum lateral deflection determined from the simulation will be a lower bound estimate of the deflection expected in a crash test. In a crash test, any spalling or concrete failure occurring at the barrier toe near the impacted connections can cause additional rotation of the barrier segments. This can result in slightly greater overall deflection of the barrier than determined through simulation analysis.
    The 9-inch x 28-inch scupper opening at the bottom of the barrier poses a potential for interacting with the wheel of an impacting small passenger car in a manner that can cause wheel snagging. To evaluate this, the researchers will perform a simulation with a small passenger car impacting the barrier close to the upstream edge of the scupper opening. The MASH evaluation criteria require the small passenger vehicle used for crash testing to have a mass of 2420 lb. Currently, there is no public domain vehicle model available that meets the mass requirements of the MASH small passenger car. Due to the unavailability of a 2420-lb small car vehicle model, the researchers will perform the simulation analysis using a Dodge Neon model developed by NCAC. This vehicle model is the closest match to the MASH design vehicle and has a total mass of 2908 lb. While the mass of the Dodge Neon vehicle model is slightly higher than the MASH design vehicle, the height and location of the wheels is very similar. Thus, for the purpose of evaluating potential for wheel snagging by the scupper, the use of Dodge Neon model should be adequate.

Task 3 -- Construction of Full-Scale Test Installation
    Information gathered from the previous tasks will be used to construct 12 barrier segments. Prior to constructing the barrier units, detailed drawings will be submitted to WSDOT for review and approval. The total length of the test installation constructed for this task will be 150 ft. TTI will document and obtain all specifications for materials used to construct the test installation.

Task 4 -- Full-Scale Crash Testing of WSDOT Pin and Loop Barrier
    Once the test installation is constructed, a full-scale crash test will be performed on the new pin and loop barrier system. The researchers will perform test 3-11 of MASH (2270P vehicle, 62 mi/hr, 25 deg) on the selected design. TTI will provide the test facility, test vehicle, instrumentation of the vehicle, high-speed film, video, still photographs, and a final report suitable for submittal to Federal Highway Administration (FHWA).

Crash Test Report - May 2010

TTI Research Supervisor: William F. Williams, P.E. Texas Transportation Institute Texas A&M University System TAMU 3135 College Station, Texas 77843-3135 (979) 862-2297 w-williams@tamu.edu

Pooled Fund Technical Representative: Rod Erickson P.E. Washington State Department of Transportation Transportation Building 310 Maple Park Avenue P.O. Box 47329 Olympia, Washington 98504-7329 EricksR@wsdot.wa.gov

QUARTERLY PROGRESS REPORTS:
March 2010 Progress Report