Washington State Department of Transportation Pin and Loop Barrier with Drainage Slots: Phase II (FY 2011)
To See Phase I
PROBLEM STATEMENT
The Washington State Department of Transportation (WSDOT) has developed preliminary details for a 34-inch tall concrete barrier utilizing a pin and loop connection. This proposed barrier will be constructed using segments 12 ft-6 inches in length. The proposed barrier will be 8 inches wide at the top and 20 inches wide at the base. The barrier will incorporate a “V”-shaped recess located at the base of the barrier in the longitudinal axis of the barrier. This slot will serve to promote better contact between the barrier and the pavement surface when “high spots” are encountered in the pavement surface. Each barrier segment will incorporate a 9 inches high by 28 inches long drainage slot (scupper) that penetrates through the barrier segment at the base. This drainage slot will be used to channel storm water from the roadway through the barrier onto the roadside or into stormwater containment facilities.
TTI designed and developed a pin and loop barrier with drainage slots in Fiscal Year 2010 (1). This barrier was crash tested on February 24, 2010, in accordance with MASH Test Level 3 (TL-3) specification (2). The barrier did not meet the crash performance requirements of the MASH specifications. The vehicle rolled over immediately after impact with the barrier installation. After further review of the crash performance of the barrier design, the project team concluded that the tolerance in the pin connection needed to be reduced to decrease the lateral dynamic deflection of the barrier from the impact of the pick-up truck. Increasing the pin diameter is the preferred option for reducing the tolerance in the connection. By increasing the pin diameter, deformation in the pin will be likely be reduced, thus, further reducing the dynamic deflection of the barrier system from impact with the TL-3 pick-up truck. The larger pin diameter will also decrease the gap between adjacent barrier segments. For additional information please refer to the details shown in Figure 1. The purpose of this project will be review the strength of the barrier connection, perform engineering analyses to size the new barrier connection pin, and perform a new crash test on the same barrier design as tested in February 2010 using a new/revised pin connection design. The crash test will be performed with respect to MASH TL-3 specifications.
Figure 1. Pin & Loop Barrier with Drainage Slots (1).
BACKGROUND
Adequate storm water drainage is necessary for safety on vehicular bridges and roadways. WSDOT has developed a single slope concrete barrier that provides drainage to scupper openings located through the base of each barrier segment. This barrier is planned for use on high speed roadways where drainage of the pavement surface is needed. The purpose of this project will be review the proposed barrier geometry, perform engineering analyses to size reinforcing steel and placement to resist TL-3 impact, and perform computer modeling simulation to predict the barrier performance with respect to MASH crash specifications for Test Level 3 impact conditions.
OBJECTIVE
The objective of this project will be to develop a single slope concrete barrier with a pin and loop connection with drainage scuppers through the barrier units that meets Test Level 3 crash performance specifications of MASH .
BENEFITS
This project will provide WSDOT with a viable concrete barrier option that provides drainage scuppers as well as satisfies the crash performance requirements of MASH crash specifications for Test Level 3 impact conditions.
NOTE: Crash test performed September 27, 2011. Report forthcoming.
| TTI Research Supervisor: William F. Williams, P.E. Texas Transportation Institute Texas A&M University System 3135 TAMU 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 |
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(1) William F. Williams, Nauman M. Sheikh, and Wanda L. Menges, “MASH Test 3-11 of the WSDOT Pin and Loop Concrete Barrier with Drainage Slots,” Test Report No. 405160-18-1, Texas Transportation Institute, The Texas A&M University Systems, College Station, TX, November 2010.
(2) AASHTO, “Manual for Assessing Safety Hardware,” Washington, DC, American Association of State Highway and Transportation Officials, 2009.
