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| Author | : Akram Y. Abu-Odeh |
| Publisher | : |
| Total Pages | : 266 |
| Release | : 2019 |
| Genre | : Automobiles |
| ISBN | : |
| Author | : Chiara Silvestri Dobrovolny |
| Publisher | : |
| Total Pages | : 0 |
| Release | : 2021 |
| Genre | : Automobiles |
| ISBN | : |
Concrete median barriers are designed to mitigate serious cross-median crashes by preventing penetration of errant vehicles into oncoming traffic. When implemented in flood-prone areas, however, solid concrete median barriers can act as a dam to floodwaters, as recently seen in Texas during Hurricane Harvey or in Louisiana and Pennsylvania following severe storms. These severe weather events raise the height of floodwaters and increase the severity of flooding on highways and surrounding roads and communities. In this study, new median barrier options with openings were investigated as a way to reduce flooding. Finite element simulations were used to aid investigation and evaluation of the designs, and laboratory testing was performed to evaluate the hydraulic efficiency of barrier designs in a variety of simulated flood conditions. A concrete single-slope profile median barrier with a large scupper was selected for crash testing following Manual for Assessing Safety Hardware (MASH) Test Level 4 impact conditions and evaluation criteria. The median barrier design was deemed MASH compliant and is ready for implementation in areas susceptible to flooding, with the goals of reducing flooding severity, decreasing associated risk to motorists, and reducing the level of flood damage to both highways and surrounding areas.
| Author | : Nauman Mansoor Sheikh |
| Publisher | : |
| Total Pages | : 0 |
| Release | : 2021 |
| Genre | : Automobiles |
| ISBN | : |
Researchers at the Texas A&M Transportation Institute (TTI) designed and tested a Manual for Assessing Safety Hardware (MASH) Test Level 4 (TL-4) compliant metal guardrail system. The researchers first developed several preliminary design concepts of the guardrail system, one of which was selected by the Texas Department of Transportation (TxDOT) for further development through simulation and crash testing. The researchers then developed a full-scale finite element model of the selected system and performed impact simulations under MASH TL-4 impact conditions. Using the results of these impact simulations, the researchers made further improvements to the guardrail design and developed the final system design details for crash testing. TTI then constructed the guardrail installation and performed MASH Test 4-12 with a single unit truck, MASH Test 4-11 with a pickup truck, and MASH Test 4-10 with a small car to meet MASH TL-4 compliance criteria for longitudinal barriers. This report provides details of the guardrail design development, the crash tests and results, and the performance assessment of the guardrail system for MASH TL-4 longitudinal barrier evaluation criteria. The design developed under this research project provides a MASH TL-4 compliant guardrail system that allows TxDOT to provide enhanced roadside safety in corridors that experience above-average heavy vehicle traffic.
| Author | : Chiara Silvestri Dobrovolny |
| Publisher | : |
| Total Pages | : 96 |
| Release | : 2018 |
| Genre | : Automobiles |
| ISBN | : |
In response to the implementation requirements set forth by the Federal Highway Administration, the Texas Department of Transportation Bridge, Design, Maintenance, and Traffic Operations Divisions reviewed their standards for roadside safety devices and identified those devices that require testing and evaluation to assess MASH compliance. Under this phase of the project, the Low-Profile MASH Concrete Barrier (LPCB-13) was evaluated. The objective of this project was to design a TL-3 low-profile barrier for high speed applications and assess its performance according to the safety-performance evaluation guidelines included in MASH for Test Level 3 (TL-3) longitudinal barriers. Based on the detailed computer model simulations results, researchers performed MASH full-scale crash tests on a low-profile portable concrete barrier system comprised of 26-inch tall, 30-ft long barrier segments with a T-shape profile. Based on constructbility feedback, researchers modified the straight side of the barrier to a 1:18 slope, to allow for easiness of construction forming tje TL-3 Low -Profile Barrier performed acceptably as a MASH TL-3 longitudinal barrier.
| Author | : Nauman Mansoor Sheikh |
| Publisher | : |
| Total Pages | : 0 |
| Release | : 2020 |
| Genre | : Automobiles |
| ISBN | : |
The objective of this project was to develop transition designs for three cast in place concrete barrier combinations. These included transitions for connecting (a) TxDOT's 36-inch tall Single Slope Traffic Rail (SSTR) to 42-inch tall Single Slope Concrete Barrier (SSCB), (b) 32-inch tall F-shape concrete barrier to SSCB, and (c)TxDOT's 32-inch tall T221 vertical concrete wall to SSCB. The designs were required to meet AASHTO [Manual for Assessing Safety Hardware] MASH Test Level 3 (TL-3) criteria, and their compliance was to be evaluated using a combination of past testing results, impact simulation analyses, and limited full scale testing. Researchers developed designs and reinforcement details for all three transitions. The transition from SSTR to SSCB was comprised of a single slope barrier profile on the traffic side. This design did not require simulation or testing due to the known MASH compliance of the single slope barrier profile. Researchers developed designs of the other two transitions by performing dynamic vehicular impact simulations using MASH TL-3 impact conditions. Using results of these simulations, researchers selected the most critical cases for performance of full scale crash tests. The design selected for full scale testing was the transition between T221 and SSCB. MASH requires performing Test 3-20 (small car) and Test 3-21 (pickup) to evaluate transition designs. Both tests were performed on the transition between T221 and SSCB. The direction of vehicle impact in both tests was from the side of the SSCB to T221, which was selected based on simulation results. The transition performed acceptably in both tests for MASH TL-3 criteria. Based on the results of the simulations for F-shape to SSCB transition, and the fact that the more critical design of T221 to SSCB transition passed MASH testing, the F-shape to SSCB transition was also considered a MASH compliant design. This report provides details of the transition designs, simulation analyses,
| Author | : Nauman Mansoor Sheikh |
| Publisher | : |
| Total Pages | : 52 |
| Release | : 2019 |
| Genre | : Automobiles |
| ISBN | : |
The purpose of the testing reported herein was to assess the performance of the free-standing single slope concrete barrier (SSCB) with cross-bolt connections according to the safety-performance evaluation guidelines included in American Association of State Highway and Transportation Officials' Manual for Assessing Safety Hardware (MASH) for Test Level Four (TL-4). The crash test performed was in accordance with MASH Test 4-12 criteria, which involves a 10000S single unit truck impacting the barrier at a target impact speed and angle of 56 mi/h and 15°, respectively. The free-standing SSCB with cross-bolt connection successfully contained and redirected the single unit truck. The barrier performed acceptably for MASH Test 4-12. The maximum dynamic and permanent barrier deflections were each 33.0 inches. In addition to the TL-4 crash test, researchers performed a detailed finite element analysis to determine the expected lateral deflection of the barrier under MASH Test 4-11 conditions, which involve impacting the barrier with a 2270P pickup truck vehicle with a target impact speed and angle of 62 mi/h and 25°, respectively. The maximum lateral barrier deflection for the pickup truck impact was estimated to be in the range of 12.5 inches to 16.8 inches.
| Author | : Robert W. Bielenberg |
| Publisher | : |
| Total Pages | : 102 |
| Release | : 2018 |
| Genre | : Roads |
| ISBN | : |
The Ohio Department of Transportation (ODOT) requested an evaluation of an unreinforced, single-slope concrete median barrier capable of satisfying Test Level 3 (TL-3) safety requirements found in the Manual for Assessing Safety Hardware, Second Edition (MASH 2016). The barrier was designed with a height of 42 in. (1,067 mm), a base width of 28 in. (711 mm), and top width of 12 in. (305 mm). The tarmac surface was milled down 1 in. (25 mm) to accommodate the barrier and asphalt pad. The barrier was cast in place using concrete with a minimum compressive strength of 4,000 psi (27.6 MPa). Expansion joints were installed in 20-ft (6.1-m) intervals to simulate cracking and potential barrier discontinuities. An asphalt pad, installed on the milled surface using a tack coat, functioned as the barrier keyway and extended 96 in. (2,438 mm) from the traffic and back sides of the barrier. Previous testing of similar single-slope concrete barriers indicated that only one full-scale crash test (MASH test designation no. 3-11) was needed to satisfy TL-3 criteria. During the test, the 5,001-lb (2,268-kg) pickup impacted the installation at a speed of 62.8 mph (101.0 km/h) and at an angle of 24.9 degrees for an impact severity of 116.3 kip-ft (157.7 kJ). The vehicle was safely contained and redirected, and the test satisfied safety performance evaluation criteria of test designation no. 3-11 found in MASH 2016.
| Author | : William F. Williams (Transportation engineer) |
| Publisher | : |
| Total Pages | : 0 |
| Release | : 2020 |
| Genre | : Automobiles |
| ISBN | : |
Texas Transportation Institute (TTI) researchers performed an extensive literature review of bridge railing transitions crash tested to Manual for Assessing Safety Hardware (MASH) TL-3, and incorporated the information obtained from this review into the design and details for the new transition testing developed for this project. TTI researchers developed concepts for the new transition anchored to a concrete wing wall. TTI researchers developed a full-scale, three-dimensional finite element model of the guardrail transition. The modeling effort included developing and validating a subcomponent level model of the post installed on concrete. Upon completion of the simulations, TTI researchers processed the results and assessed the likelihood of the transition system passing the required MASH crash tests. TTI researchers noted the design deficiencies and recommended design modifications to the system to mitigate those deficiencies. TTI researchers developed full-scale test installation drawings of the design after the finite element model simulations were completed and all the results were reviewed with favorable results. After approval of the test installation drawings by Texas Department of Transportation (TxDOT), construction of a full-scale test installation for crash testing commenced, and crash tests were performed on the full-scale test installation. The Guardrail to Rigid Barrier Transition Attached to Bridge or Culvert Structure, used on the upstream and downstream ends, performed acceptably for MASH TL-3 transitions.
| Author | : Akram Y. Abu-Odeh |
| Publisher | : |
| Total Pages | : 0 |
| Release | : 2021 |
| Genre | : Automobiles |
| ISBN | : |
The purpose of this research was to develop a Manual for Assessing Safety Hardware (MASH) Test Level 3 (TL-3) compliant transition between a median guardrail and median concrete barrier, and then test the design according to MASH TL-3 crash testing guidelines. The design was developed using finite element computer simulations. This report provides details on the computer simulations, the Texas Department of Transportation (TxDOT) median transition system, the crash tests and results, and the performance assessment of the median transition for MASH TL-3 transition evaluation criteria. The TxDOT median transition met the performance criteria for MASH TL-3 transitions.
| Author | : Akram Y. Abu-Odeh |
| Publisher | : |
| Total Pages | : 98 |
| Release | : 2014 |
| Genre | : Median strips |
| ISBN | : |
