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FULL-SCALE VEHICLE CRASH TEST ON THE IOWA STEEL TEMPORARY BARRIER RAIL
Abstract and Figures
One full-scale vehicle crash test was conducted on the Iowa Steel Temporary Barrier Rail. Test 15-1 was conducted with at 5,500 pound vehicle at 22.5 degrees and 60.6 mph. The overall test length of the barrier was 200 feet. The barrier was shop fabricated and transported to the test site in 20 foot length sections. The cross-section of the barrier consisted of two stacked steel HP 14x73 (A36) shapes with the edges of the flanges placed back to back and held together by welded steel straps spaced 5 feet on centers. The inside box section between the HP shapes was filled with concrete. The height of the barrier was 29 inches. The 20 foot length sections were bolted together at the test site. The location of the vehicle impact was 100 feet from the end of the barrier installation. This was also the location where two sections were bolted together. The test was evaluated according to the safety criteria in NCHRP 230 and also in the AASHTO guide specifications, performance level 2. The safety performance of the Iowa Steel Temporary Barrier Rail was determined to be satisfactory.
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... It is believed that barriers with a vertical-shape front face would demonstrate markedly better vehicle stability when struck. The vehicle instability observed during previous testing of freestanding F-shape temporary barriers (12) and the improved stability observed during testing of freestanding and tie-down vertical shape temporary barriers (13,14) appear to support that conclusion. ...
Temporary concrete barriers are one of the most common types of roadside hardware found on the nation's highways. However, unresolved issues exist for some installations. These issues include the need for a tie-down system for barrier installations placed on asphalt roadway surfaces and an approach transition between temporary concrete barriers and rigid barriers. The objective of this research was to design a tie-down temporary barrier for use on asphalt road surfaces and then apply that tie-down system to the design of an approach transition from freestanding to rigid barriers. The tie-down and transition systems were to be evaluated according to Test Level 3 safety performance criteria set forth in NCHRP Report No. 350. For the asphalt tie-down system, three steel pins were installed in holes on the front face of the barrier. The new tie-down design was crash tested according to NCHRP Report No. 350 Test Designation 3-11. The test was judged acceptable, barrier deflections were reduced, and all barriers in the system were safely restrained. The approach transition to rigid barrier was developed through strategic application of the previously designed asphalt tie-downs. Computer simulation with LS-DYNA was used to locate the critical impact point for the full-scale crash test. The system was tested according to NCHRP Report No. 350 Test Designation 3-21. Results show that the vehicle was safely redirected, and the test was judged acceptable. Recommendations concerning the application of both the tie-down and transition designs are given.
The Iowa Department of Transportation typically builds separation barriers between vehicle and pedestrian/bicycle facilities when sidewalks or trails are present on vehicular bridges. Currently, Iowa DOT employs a combination bridge rail that utilizes a concrete parapet that previously had been successfully evaluated to National Cooperative Highway Research Program (NCHRP) Report 350 Test Level 4 (TL-4) criteria for these situations. While the parapet had been successfully evaluated, the combination bridge rail system as a whole had not been evaluated to any crash test standards. Iowa DOT desired that researchers at Midwest Roadside Safety Facility (MwRSF) design and test a combination bridge separation barrier to current Manual for Assessing Safety Hardware (MASH) TL-2 standards to use in place of their current, untested system. During this effort, previous combination rails, low-height vertical parapets, and zone of intrusion (ZOI) studies were reviewed to provide guidance on system design. A simulation effort was also performed to aid in height selection of the parapet, as well as placement of the attached bicycle rail to reduce the amount of negative vehicle-to-rail interaction with the system. Using the information gathered during the review of previous systems and simulation effort, a full system design was produced. It was then recommended that the proposed system be evaluated to MASH test designation 2-11 in order to assess the system’s performance during a vehicle impact scenario. Advisor: John D. Reid
Two tie-down temporary barrier systems were developed and crash tested according to the safety performance criteria provided in NCHRP Report 350: Recommended Procedures for the Safety Performance Evaluation of Highway Features. Both tie-down systems were designed to reduce barrier displacements and to retain deflected barriers on the bridge deck edge. The first system consisted of a steel tie-down strap concept for use with the Iowa F-shape temporary concrete barrier. At each barrier joint, the trapezoidal-shaped strap retained the vertical pin and was attached to the concrete bridge deck using two drop-in anchors. An acceptable fullscale vehicle crash test of the tie-down strap concept was conducted according to the Test Level 3 (TL-3) impact safety standards in NCHRP Report 350. The second tie-down system was developed for use with Iowa's steel H-section temporary barrier. A new barrier connection was developed to simplify barrier attachment and to accommodate deviations in horizontal and vertical alignment. It consisted of two steel shear plates positioned within an opening on the adjacent barrier section and held in place with two steel drop pins. Four steel angle brackets were welded to the barrier's base to allow for rigid attachment to the concrete bridge deck with drop-in anchors. Two full-scale vehicle crash tests were conducted on the steel H-barrier system according to TL-3 impact safety standards found in NCHRP Report 350. After an unacceptable first test, the system was successfully tested with minor design modifications.
Full-Scale Vehicle Crash Test on the Iowa Temporary Concrete Barrier Rail Half-Section
- R K Faller
- J A Magdaleno
- E R Post
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