Minimum Effective Length for the Midwest Guardrail System

2015 ◽  
Vol 2521 (1) ◽  
pp. 67-78 ◽  
Author(s):  
Jennifer D. Schmidt ◽  
John D. Reid ◽  
Nicholas A. Weiland ◽  
Ronald K. Faller
Keyword(s):  
System Performance ◽  
Evaluation Criteria ◽  
Full Scale ◽  
Effective Length ◽  
Crash Test ◽  
Minimum Length ◽  
Test Results ◽  
Crash Testing ◽  
Level 3 ◽  
System Length

The recommended minimum length for the standard Midwest Guardrail System (MGS) is 175 ft (55.3 m) based on crash testing according to NCHRP Report 350 and AASHTO's Manual for Assessing Safety Hardware (MASH) specifications. However, varying roadside hazards and roadway geometries may require a W-beam guardrail system to be shorter than the currently tested minimum length. The effects of reducing system length for the MGS were therefore investigated. The research study included one full-scale crash test with a Dodge Ram pickup truck striking a 75-ft (22.9-m) long MGS system. The barrier system satisfied all MASH Test Level 3 (TL-3) evaluation criteria for Test Designation Number 3-11. Test results confirmed that the reduced system length did not adversely affect overall system performance or deflections. Simulations that used BARRIER VII and LS-DYNA were also conducted to analyze system performance with reduced lengths of 50 ft (15.2 m) and 62 ft 6 in. (19.1 m). Both system lengths exhibited the potential for successfully redirecting an errant vehicle at MASH TL-3 test conditions. However, these reduced-length systems would have a narrow window for redirecting vehicles and would be able to shield hazards of only a limited size. Owing to limitations associated with the computer simulations, full-scale crash testing is recommended before these shorter systems are installed.

Finite Element Simulation of a Strong-Post W-Beam Guardrail System

SIMULATION ◽  
2002 ◽  
Vol 78 (10) ◽  
pp. 587-599 ◽  
Author(s):  
Ali O. Atahan
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Full Scale ◽  
Nonlinear Finite Element ◽  
Crash Test ◽  
Original Design ◽  
Dynamic Interactions ◽  
Crash Testing ◽  
Element Simulation ◽  
Test Requirements

Computer simulation of vehicle collisions has improved significantly over the past decade. With advances in computer technology, nonlinear finite element codes, and material models, full-scale simulation of such complex dynamic interactions is becoming ever more possible. In this study, an explicit three-dimensional nonlinear finite element code, LS-DYNA, is used to demonstrate the capabilities of computer simulations to supplement full-scale crash testing. After a failed crash test on a strong-post guardrail system, LS-DYNA is used to simulate the system, determine the potential problems with the design, and develop an improved system that has the potential to satisfy current crash test requirements. After accurately simulating the response behavior of the full-scale crash test, a second simulation study is performed on the system with improved details. Simulation results indicate that the system performs much better compared to the original design.

A Base Study to Investigate MASH Conservativeness of Occupant Risk Evaluation

2020 ◽  
Vol 6 (2) ◽  
Author(s):  
Nathan Schulz ◽  
Chiara Silvestri Dobrovolny ◽  
Stefan Hurlebaus ◽  
Harika Reddy Prodduturu ◽  
Dusty R. Arrington ◽  
...  
Keyword(s):  
Risk Evaluation ◽  
Injury Risk ◽  
Evaluation Criteria ◽  
Oblique Impact ◽  
Full Scale ◽  
Crash Test ◽  
Fe Model ◽  
Vehicle Interior ◽  
Space Model ◽  
The Impact

Abstract The manual for assessing safety hardware (MASH) defines crash tests to assess the impact performance of highway safety features in frontal and oblique impact events. Within MASH, the risk of injury to the occupant is assessed based on a “flail-space” model that estimates the average deceleration that an unrestrained occupant would experience when contacting the vehicle interior in a MASH crash test and uses the parameter as a surrogate for injury risk. MASH occupant risk criteria, however, are considered conservative in their nature, due to the fact that they are based on unrestrained occupant accelerations. Therefore, there is potential for increasing the maximum limits dictated in MASH for occupant risk evaluation. A frontal full-scale vehicle impact was performed with inclusion of an instrumented anthropomorphic test device (ATD). The scope of this study was to investigate the performance of the flail space model (FSM) in a full-scale crash test compared to the instrumented ATD recorded forces which can more accurately predict the occupant response during a collision event. Additionally, a finite element (FE) model was developed and calibrated against the full-scale crash test. The calibrated model can be used to perform parametric simulations with different testing conditions. Results obtained through this research will be considered for better correlation between vehicle accelerations and occupant injury. This becomes extremely important for designing and evaluating barrier systems that must fit within geometrical site constraints, which do not provide adequate length to redirect test vehicles according to MASH conservative evaluation criteria.

scholarly journals Repeatability of Full-Scale Crash Tests and Criteria for Validating Simulation Results

1996 ◽  
Vol 1528 (1) ◽  
pp. 155-160 ◽  
Author(s):  
Malcolm H. Ray
Keyword(s):  
Finite Element ◽  
Full Scale ◽  
Crash Test ◽  
Test Results ◽  
Finite Element Analyses ◽  
Element Analysis ◽  
Acceleration Time Histories ◽  
Time Histories ◽  
Simulation Results ◽  
Crash Tests

A method of comparing two acceleration time histories to determine whether they describe similar physical events is described. The method can be used to assess the repeatability of full-scale crash tests and it can also be used as a criterion for assessing how well a finite-element analysis of a collision event simulates a corresponding full-scale crash test. The method is used to compare a series of six identical crash tests and then is used to compare several finite-element analyses with full-scale crash test results.

Test Level 4 Bridge Rails

2000 ◽  
Vol 1720 (1) ◽  
pp. 80-94
Author(s):  
C. Eugene Buth ◽  
Wanda L. Menges ◽  
William F. Williams
Keyword(s):  
Full Scale ◽  
Safety Performance ◽  
Crash Test ◽  
Test Results ◽  
Recent Past ◽  
Design Specifications ◽  
Performance Requirements ◽  
Steel Tubing ◽  
Aashto Lrfd ◽  
Test Level

Design details and full-scale crash test results are presented for three bridge rails tested for compliance with NCHRP Report 350 Test Level 4 requirements. Designs of these rails are based on AASHTO LRFD Bridge Design Specifications. Each bridge rail consists of structural steel tubing rail elements mounted on wide-flange posts. The rails are generally stronger than many designs commonly used in the recent past. Full-scale crash test results demonstrated that all bridge rails meet NCHRP Report 350 safety performance requirements.

A Base Study to Investigate MASH Conservativeness of Occupant Risk Evaluation

2016 ◽  
Author(s):  
Chiara Silvestri Dobrovolny ◽  
Harika Reddy Prodduturu ◽  
Dusty R. Arrington ◽  
Nathan Schulz ◽  
Stefan Hurlebaus ◽  
...  
Keyword(s):  
Risk Evaluation ◽  
Injury Risk ◽  
Evaluation Criteria ◽  
Oblique Impact ◽  
Full Scale ◽  
Crash Test ◽  
Vehicle Interior ◽  
Impact Performance ◽  
Space Model ◽  
The Impact

The Manual for Assessing Safety Hardware (MASH) defines crash tests to assess the impact performance of highway safety features in frontal and oblique impact events. Within MASH, the risk of injury to the occupant is assessed based on a “flail-space” model that estimates the average deceleration that an unrestrained occupant would experience when contacting the vehicle interior in a MASH crash test and uses the parameter as a surrogate for injury risk. MASH occupant risk criteria, however, are considered conservative in their nature, due to the fact that they are based on unrestrained occupant accelerations. Therefore, there is potential for increasing the maximum limits dictated in MASH for occupant risk evaluation. A frontal full-scale vehicle impact was performed with inclusion of an instrumented anthropomorphic test device (ATD). The scope of this study was to investigate the performance of the Flail Space Model in a full scale crash test compared to the instrumented ATD recorded forces which can more accurately predict the occupant response during a collision event. Results obtained through this research will be considered for better correlation between vehicle accelerations and occupant injury. This becomes extremely important for designing and evaluating barrier systems that must fit within geometrical site constraints, which do not provide adequate length to redirect test vehicles according to MASH conservative evaluation criteria.

NCHRP Report 350 Crash Test Results for Connecticut Truck-Mounted Attenuator

1996 ◽  
Vol 1528 (1) ◽  
pp. 52-60
Author(s):  
John F. Carney ◽  
Charles E. Dougan ◽  
Eric C. Lohrey
Keyword(s):  
Full Scale ◽  
Test Series ◽  
Crash Test ◽  
Test Results ◽  
Impact Attenuation ◽  
Crash Tests ◽  
Test Level ◽  
Level 2

The results of four full-scale crash tests performed on the Connecticut Truck Mounted Attenuator (CTMA) are summarized. The tests were conducted in accordance with the guidelines of NCHRP Report 350 for Test Level 2 devices. NCHRP Report 350 specifies two required and two optional tests. The four crash tests passed all requirements of NCHRP Report 350. No repeat tests were required, and the results were uniformly excellent. The successful CTMA test series is the first of several NCHRP Report 350 test programs that are anticipated to gain compliance for various impact attenuation systems designed and developed in Connecticut.

Development of a 100-km/h Reusable High-Molecular Weight/High-Density Polyethylene Truck-Mounted Attenuator

1998 ◽  
Vol 1647 (1) ◽  
pp. 75-88
Author(s):  
John F. Carney ◽  
Subhasish Chatterjee ◽  
Richard B. Albin
Keyword(s):  
Molecular Weight ◽  
Kinetic Energy ◽  
High Molecular Weight ◽  
High Density Polyethylene ◽  
Full Scale ◽  
High Density ◽  
Crash Test ◽  
Crash Testing ◽  
Impact Attenuation ◽  
Risk Parameters

A reusable truck-mounted attenuator has been developed that dissipates kinetic energy through the lateral deformation of a nested cluster of high-molecular weight/high-density polyethylene cylinders. This 100-km/h impact attenuation device, called the Vanderbilt truck-mounted attenuator (VTMA), satisfies the crash testing requirements of NCHRP Report 350. It has been approved by the Federal Highway Administration for use on the national highway system under these NCHRP Report 350 guidelines. Most impact attenuation devices currently employed require the replacement of damaged structural components and spent-energy-dissipating elements following an impact event. Until these repairs and refurbishments are carried out, these safety devices are largely ineffective because they are unable to dissipate kinetic energy in a subsequent impact in an acceptable manner such that relevant occupant risk parameters are within prescribed limits. The VTMA is a reusable and self-restorative truck-mounted attenuator. It can dissipate large amounts of kinetic energy, undergo significant deformations and strains without fracturing, and then, essentially, regain its original shape and energy-dissipation potential on removal of the load. The VTMA design was optimized through finite-element modeling using DYNA3D. This inexpensive modeling tool resulted in a reduction in the number of expensive full-scale crash tests required to develop the system. Computer modeling can optimize the probability for success of a given full-scale crash test, removing the trial-and-error approach to appurtenance design.

Development of a New Manual for Assessing Safety Hardware TL-3 Low-Profile Portable Concrete Barrier for High-Speed Applications

2019 ◽  
Vol 2673 (7) ◽  
pp. 630-640
Author(s):  
Chiara Silvestri Dobrovolny ◽  
Shengyi Shi ◽  
James Kovar ◽  
Roger P. Bligh ◽  
Stefan Hurlebaus
Keyword(s):  
High Speed ◽  
Evaluation Criteria ◽  
Full Scale ◽  
Crash Testing ◽  
Sight Distance ◽  
Low Profile ◽  
Rail Systems ◽  
Distance Problem ◽  
Crash Tests ◽  
Concrete Barrier

A sight-distance problem is associated with use of 32-in. tall concrete longitudinal barriers, specifically in certain work zone locations and at nighttime. These 32-in. tall barriers can obstruct drivers’ eyesight, making it difficult for drivers to detect oncoming vehicles on the other side of these barriers. To address this sight-distance problem while protecting the errant vehicles, researchers at the Texas Transportation Institute (TTI) developed a 20-in. tall low-profile portable concrete barrier (PCB) for use in low-speed work zones in the early 1990s. To address the problem for high-speed application, TTI researchers applied modifications to the 20-in. tall low-profile PCB. Researchers designed two retrofit metal rail systems to be added on top of the existing 20-in. tall low-profile PCB to address roadside and median applications. The systems successfully performed in full-scale crash testing according to NCHRP Report 350 Test Level (TL) 3 evaluation criteria. This paper describes the efforts to develop and evaluate the crashworthiness of a new low-profile PCB design for high-speed applications. The crash tests were performed following Manual for Assessing Safety Hardware (MASH) guidelines and evaluation criteria. Based on results from finite element computer simulations performed to aid design, MASH full-scale crash tests were conducted on a low-profile PCB system comprised of 26-in. tall, 30-ft long barrier segments, with a T-shaped profile. Based on constructability feedback, the sides of the barrier were formed with a negative 1:18 slope, which allows for ease of construction forming. The new low-profile PCB performed acceptably as a MASH TL-3 longitudinal barrier.

scholarly journals Development of a Test Level 3 Transition Between Guardrail and Portable Concrete Barriers

2017 ◽  
Vol 2638 (1) ◽  
pp. 77-87 ◽  
Author(s):  
Robert W. Bielenberg ◽  
David Gutierrez ◽  
Ronald K. Faller ◽  
John D. Reid ◽  
Phil Tenhulzen
Keyword(s):  
Systems Design ◽  
Road Construction ◽  
Full Scale ◽  
Performance Criteria ◽  
Work Zones ◽  
Design Concepts ◽  
Crash Testing ◽  
Concrete Barriers ◽  
Level 3 ◽  
Test Level

Road construction often requires that work zones be created and shielded by portable concrete barriers (PCBs) to protect workers and equipment from errant vehicles as well as to prevent motorists from striking other roadside hazards. For an existing W-beam guardrail system installed adjacent to the roadway and near the work zone, guardrail sections are removed so a PCB system can be placed. A study was done to develop a crashworthy transition between W-beam guardrail and PCB systems. Design concepts were developed and refined through computer simulation with LS-DYNA. Additionally, a study of critical impact points was conducted to determine impact locations for full-scale crash testing. The design effort resulted in a new system consisting of a Midwest Guardrail System that overlapped a series of F-shape PCB segments placed at a 15:1 flare. In the overlapped region of the barrier systems, uniquely designed blockout supports and a specialized W-beam end shoe mounting bracket were used to connect the systems. Three full-scale vehicle crash tests were successfully conducted according to the Manual for Assessing Safety Hardware Test Level 3 safety performance criteria. Because of the successful test results, a Test Level 3 crashworthy guardrail-to-PCB transition system is now available for protecting motorists, workers, and equipment in work zones.

Long-Span Guardrail System for Culvert Applications

2000 ◽  
Vol 1720 (1) ◽  
pp. 19-29 ◽  
Author(s):  
Ronald K. Faller ◽  
Dean L. Sicking ◽  
Karla A. Polivka ◽  
John R. Rohde ◽  
Bob W. Bielenberg
Keyword(s):  
Simulation Modeling ◽  
Research Study ◽  
Full Scale ◽  
Wood Block ◽  
Long Span ◽  
Crash Testing ◽  
Vehicle Crash ◽  
Level 3 ◽  
Crash Tests ◽  
Test Level

A long-span guardrail for use over low-fill culverts was developed and successfully crash tested. The guardrail system was configured with 30.48 m of nested, 12-gauge W-beam rail and centered around a 7.62-m-long unsupported span. The nested W-beam rail was supported by 16 W152×13.4 steel posts and 6 standard CRT posts, each with two 150-mm×200×360 mm wood block-outs. Each post was 1830 mm long. Post spacings were 1905 mm on center, except for the 7.62-m spacing between the two CRT posts surrounding the long span. The research study included computer simulation modeling with Barrier VII and full-scale vehicle crash testing, using 3/4-ton (680-kg) pickup trucks in accordance with the Test Level 3 (TL-3) requirements specified in NCHRP Report 350. Three full-scale vehicle crash tests were performed. The first test was unsuccessful because of severe vehicle penetration into the guardrail system. This penetration resulted from a loss of rail tensile capacity during vehicle redirection when the swagged fitting on the cable anchor assembly failed. A second test was performed on the same design, which contained a new cable anchor assembly. During vehicle redirection, the pickup truck rolled over and the test was considered a failure. The long-span system was subsequently redesigned to incorporate double block-outs on the CRT posts and crash tested again. Following the successful third test, the long-span guardrail system was determined to meet TL-3 criteria.

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