Development and Implementation of the Simplified Midwest Guardrail System Stiffness Transition

2012 ◽  
Vol 2309 (1) ◽  
pp. 81-93 ◽  
Author(s):  
Karla A. Lechtenberg ◽  
Scott K. Rosenbaugh ◽  
Robert W. Bielenberg ◽  
Mario Mongiardini ◽  
Ronald K. Faller ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Gradual Increase ◽  
Lateral Stiffness ◽  
Potential Hazard ◽  
Crash Testing ◽  
Level 3 ◽  
Successful Testing ◽  
Beam Bridge ◽  
Departments Of Transportation ◽  
Test Level

The varied lateral stiffness between bridge rails and approach guardrail systems may cause vehicle pocketing or wheel snagging to occur near rigid bridge rail ends. To mitigate this potential hazard, an approach guardrail transition (AGT) is used to provide a gradual increase in the lateral stiffness of the barrier between the W-beam guardrail system and the bridge railing. However, these transitions can also cause a propensity for vehicle pocketing or wheel snagging if the change in lateral stiffness occurs too rapidly. Recently, a stiffness transition based on NCHRP Report 350 was developed for use with the Midwest Guardrail System (MGS) and a stiff Thrie beam AGT, and successful testing was performed close to the upstream end of the AGT. The transition was designed with three sizes of steel posts, one of which was nonstandard for state departments of transportation. Thus, a simplified version of the original MGS stiffness transition that used two common sizes of steel posts was developed and was subjected to full-scale crash testing according to Test Level 3 as set forth in the Manual for Assessing Safety Hardware. Subsequently, dynamic post properties obtained from bogie testing and numerical simulations were used to develop an equivalent wood post version of the simplified MGS stiffness transition. Recommendations are made regarding the attachment of the stiffness transitions to FHWA-accepted Thrie beam bridge rail AGTs.

Crash Testing and Evaluation of Culvert-Mounted Midwest Guardrail System

2020 ◽  
Vol 2674 (7) ◽  
pp. 161-171
Author(s):  
Mojdeh Asadollahi Pajouh ◽  
Robert W. Bielenberg ◽  
Jennifer D. Schmidt-Rasmussen ◽  
Ronald K. Faller
Keyword(s):  
American Association ◽  
Water Drainage ◽  
Test Installation ◽  
State Highway ◽  
Crash Testing ◽  
Test Number ◽  
Box Culverts ◽  
Level 3 ◽  
Crash Tests ◽  
Test Level

Concrete box culverts are usually installed under roadways to allow water drainage without affecting the motoring public. Culvert openings can represent a hazard on the roadside when they do not extend outside of the clear zone, and often require safety treatments in the form of roadside barriers. In this study, a modified design of Midwest Guardrail System (MGS) was evaluated for installation on a low-fill culvert with the strong-post attachment using through-bolts and epoxy anchorage through full-scale crash testing. The test installation consisted of MGS with a 31 in. top rail height, supported by W6 × 9 posts, spaced at 37½ in., attached to a low-fill culvert’s top slab with a 12 in. offset from the back of the post to the culvert headwall. Two crash tests were conducted according to the American Association of State Highway and Transportation Officials’ (AASHTO) Manual for Assessing Safety Hardware (MASH) 2016 Test Level 3 impact safety criteria. In test number CMGS-1, a 2,428-lb car impacted the MGS attached to the culvert at a speed of 61.3 mph and at an angle of 25.1°. In test number CMGS-2, a 5,013-lb pickup truck impacted the MGS attached to the culvert at a speed of 62.8 mph and an angle of 25.7°. In both tests, the vehicle was safely redirected and captured. Both tests were deemed acceptable according to TL-3 safety criteria in MASH. Recommendations were made for the safe installation of MGS atop low-fill culverts as well as transitions from the standard MGS to the culvert-mounted MGS.

Test Level 2 Guardrail-to-Bridge Rail Transition Compatible with 31-in. Guardrail

2013 ◽  
Vol 2377 (1) ◽  
pp. 74-83
Author(s):  
R. P. Bligh ◽  
D. R. Arrington ◽  
R. Meza
Keyword(s):  
High Speed ◽  
Low Cost ◽  
Transition Systems ◽  
Speed Test ◽  
Traffic Conditions ◽  
Level 3 ◽  
Common Application ◽  
Departments Of Transportation ◽  
Test Level ◽  
Level 2

Many state departments of transportation are in the process of updating their guardrail standards to comply with the AASHTO Manual for Assessing Safety Hardware (MASH) and guidance issued by FHWA on guardrail height. A key feature of the new systems is an increase in rail mounting height from 27 in. to 31 in. A common application of guardrails is shielding motorists from hazards at bridge approaches, including the end of the bridge rail. When a flexible-approach guardrail is attached to a rigid bridge rail, a transition section is needed to transition the stiffness properly from one system to another. A nested thrie beam transition system has been successfully tested to MASH guidelines and is compatible with a 31-in.-approach guardrail. However, it is cost-prohibitive to use this high-speed, Test Level 3 transition on all roadways. A low-cost transition was successfully evaluated under NCHRP Report 350 Test Level 2 (TL-2) impact conditions for use on lower-speed roadways. However, this TL-2 W-beam transition is 27 in. tall and is not compatible with the new 31-in. guardrail systems. This paper describes a new low-cost guardrail-to-bridge rail transition that was successfully developed and tested under MASH TL-2 conditions. The transition is compatible with new 31-in. guardrails and can connect to rigid concrete bridge rails. The transition is considered suitable for implementation on roadways that have traffic conditions appropriate for the use of TL-2 safety hardware. Use of this system would provide significant savings in both material and installation costs compared with high-speed transition systems.

NCHRP Report 350 Testing of W-Beam Slotted-Rail Terminal

1997 ◽  
Vol 1599 (1) ◽  
pp. 22-31 ◽  
Author(s):  
King K. Mak ◽  
Hayes E. Ross ◽  
Roger P. Bligh ◽  
Wanda L. Menges
Keyword(s):  
High Speed ◽  
Safety Performance ◽  
The Other ◽  
Federal Aid ◽  
Speed Limits ◽  
Crash Testing ◽  
National Highway ◽  
Level 3 ◽  
Test Level ◽  
Highway System

Two slotted-rail terminal (SRT) designs, one for use on roadways with speed limits of 72.4 km/hr (45 mi/hr) or less and the other for high-speed facilities, were previously developed and successfully crash-tested in accordance with guidelines set forth in NCHRP Report 230. Those SRT designs have been approved by FHWA for use on federal-aid projects. However, FHWA has since adopted NCHRP Report 350 as the official guidelines for safety performance evaluation of roadside features and required that all roadside features to be used on the National Highway System be crash-tested in accordance with the NCHRP Report 350 guidelines by 1998. It is therefore necessary to modify and retest the SRT designs in accordance with NCHRP Report 350 guidelines. The modified SRT design has successfully met the guidelines set forth in NCHRP Report 350 for Test Level 3 conditions, that is, 100-km/hr (62.2 mi/hr) and the results of the crash testing. The modified SRT design has been approved by FHWA for use on the national highway system.

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.

Retrofit Bridge Rail Design and Testing for a Historic Texas Steel Truss Bridge

2013 ◽  
Vol 2377 (1) ◽  
pp. 29-37
Author(s):  
William Williams
Keyword(s):  
Analytical Procedure ◽  
Design Procedure ◽  
Steel Truss Bridge ◽  
Crash Testing ◽  
Steel Truss ◽  
Level 3 ◽  
Truss Bridge ◽  
Design And Testing ◽  
Test Level ◽  
Level 2

The State Loop 481 steel truss bridge over the Llano River in Junction, Texas, is classified as a historic structure. The bridge is approximately 1,423 ft long and has a railing that attaches directly to the steel truss members and does not meet the current AASHTO Test Level 2 (TL-2) strength requirements. Many supporting truss members were not adequate to resist TL-2 crash force. The purpose of this research was to design a crashworthy retrofit bridge rail that met the current AASHTO TL-2 strength requirements without overstressing the supporting truss members. The new design maintains the historic appearance of the structure. This paper presents details of the new bridge rail design and an analytical procedure for determining the magnitude of force transmitted to the supporting truss members. Crushable-pipe blockouts located between the new retrofit rail design and the truss members were developed as part of this research and were used to minimize the crash force transmitted to the steel truss members. The new bridge rail design was successfully crash tested in accordance with the TL-2 requirements of NCHRP Report 350. A bridge rail expansion splice was developed for the new bridge rail design and was successfully crash tested in accordance with the Test Level 3 requirements of NCHRP Report 350. This paper presents the results of this research, details of the expansion splice, the new bridge rail design, the design procedure, and the results of the crash testing.

Dynamic Evaluation and Implementation Guidelines for a Nonproprietary W-Beam Guardrail Trailing-End Terminal

2013 ◽  
Vol 2377 (1) ◽  
pp. 61-73 ◽  
Author(s):  
Mario Mongiardini ◽  
Ronald K. Faller ◽  
John D. Reid ◽  
Dean L. Sicking
Keyword(s):  
Safety Performance ◽  
Crash Test ◽  
Impact Location ◽  
Close Proximity ◽  
Level 3 ◽  
Implementation Guidelines ◽  
Potential Risks ◽  
Departments Of Transportation ◽  
Crash Tests ◽  
Test Level

Most state departments of transportation use simple adaptations of crashworthy guardrail end terminals, which typically include breakaway posts and an anchor cable, for downstream anchorage systems. The guardrail safety performance for vehicular impacts occurring in close proximity to these simplified, downstream anchorage systems is not well known. Further, the length of need (LON) for the downstream end of these systems has yet to be adequately determined. This research project assessed the safety performance of the Midwest Guardrail System (MGS) for impacts occurring in close proximity to a nonproprietary, trailing-end guardrail terminal under the Test Level 3 conditions of the Manual for Assessing Safety Hardware. The two research objectives were to (a) determine the end of the LON for impacts with light pickup trucks and (b) investigate potential risks for a small passenger car to become unstable when striking the downstream end of the MGS anchored by the nonproprietary, trailing-end terminal. Numerical simulations were carried out to identify the most critical impact location for the 1100C small car and the end of the LON for the 2270P pickup truck. In full-scale crash tests, considerable snag of the 1100C vehicle occurred; however, occupant risk values and vehicle stability were within acceptable limits. The crash test with the 2270P pickup indicated that the end of the LON was located at the sixth post from the downstream-end post. Guidelines were proposed for installing the MGS to shield hazards in close proximity to the tested nonproprietary, trailing-end terminal.

Development of a 34-in. Tall Thrie-Beam Guardrail Transition to Accommodate Future Roadway Overlays

2019 ◽  
Vol 2673 (2) ◽  
pp. 489-501
Author(s):  
Scott K. Rosenbaugh ◽  
Ronald K. Faller ◽  
Jennifer D. Schmidt ◽  
Robert W. Bielenberg
Keyword(s):  
Full Scale ◽  
Safety Performance ◽  
Performance Criteria ◽  
Concrete Barriers ◽  
Before And After ◽  
Level 3 ◽  
Crash Tests ◽  
Test Level

Roadway resurfacing and overlay projects effectively reduce the height of roadside barriers placed adjacent to the roadway, which can negatively affect their crashworthiness. More recently, bridge rails and concrete barriers have been installed with slightly increased heights to account for future overlays. However, adjacent guardrails and approach transitions have not yet been modified to account for overlays. The objective of this project was to develop an increased-height approach guardrail transition (AGT) to be crashworthy both before and after roadway overlays of up to 3 in. The 34-in. tall, thrie-beam transition detailed here was designed such that the system would be at its nominal 31-in. height following a 3-in. roadway overlay. Additionally, the upstream end of the AGT incorporated a symmetric W-to-thrie transition segment that would be replaced by an asymmetric transition segment after an overlay to keep the W-beam guardrail upstream from the transition at its nominal 31-in. height. The 34-in. tall AGT was connected to a modified version of the standardized buttress to mitigate the risk of vehicle snag below the rail. The barrier system was evaluated through two full-scale crash tests in accordance with Test Level 3 (TL-3) of AASHTO’s Manual for Assessing Safety Hardware (MASH) and satisfied all safety performance criteria. Thus, the 34-in. tall AGT with modified transition buttress was determined to be crashworthy to MASH TL-3 standards. Finally, implementation guidance was provided for the 34-in. tall AGT and its crashworthy variations.

Development of Universal Breakaway Steel Post for Bullnose Median Barrier

2012 ◽  
Vol 2309 (1) ◽  
pp. 94-104
Author(s):  
Robert W. Bielenberg ◽  
Karla A. Lechtenberg ◽  
Dean L. Sicking ◽  
Steve Arens ◽  
Ronald K. Faller ◽  
...  
Keyword(s):  
Controlled Release ◽  
Full Scale ◽  
Successful Completion ◽  
Safe Alternative ◽  
Long Span ◽  
Level 3 ◽  
Crash Tests ◽  
Test Level ◽  
Bolt Steel ◽  
Satisfactory Manner

A new fracturing-bolt universal breakaway steel post (UBSP) was developed and evaluated for use as a replacement for the controlled-release terminal (CRT) wood post currently used in the Thrie beam bullnose system. After numerous steel post concepts were investigated, a fracturing-bolt steel post was selected as the most promising design. The fracturing-bolt steel post successfully matched the strength and dynamic behavior of the CRT wood post in three impact orientations. The UBSP was incorporated into the Thrie beam bullnose barrier system and subjected to three full-scale vehicle crash tests according to the Test Level 3 guidelines provided in NCHRP Report 350. Test Designations 3–30, 3–31, and 3–38 were chosen to evaluate the performance of the Thrie beam bullnose system with UBSPs. All three full-scale crash tests demonstrated that the UBSP performed in a satisfactory manner in the bullnose system, as the vehicle was captured and safely brought to a controlled stop. On the basis of the successful completion of the three full-scale crash tests, it is recommended that the UBSP be considered a safe alternative to CRT posts in the original Thrie beam bullnose median barrier system. It is also noted that the performance of the UBSP suggests that it may have additional applications, including in long-span guardrail, end terminals, and guardrail in mow strips or encased in pavement.

Bayesian Reconstruction of Median-Crossing Crashes and Potential Effectiveness of Cable Barriers

2005 ◽  
Vol 1908 (1) ◽  
pp. 141-147 ◽  
Author(s):  
Gary A. Davis ◽  
Jianping Pei
Keyword(s):  
Opposite Direction ◽  
Bayesian Reconstruction ◽  
Potential Effectiveness ◽  
Level 3 ◽  
The Impact ◽  
Test Level

A cross-median crash occurs when a vehicle leaves its traveled way, completely crosses the median dividing the highway's directional lanes, and collides with a vehicle traveling in the opposite direction. As the advent of divided highways reduced head-on collisions, and the prevalence of forgiving roadsides reduced fixed-object collisions, fatalities caused by median crossings became relatively more prominent. This paper describes the reconstruction of several fatal median-crossing events; the events occurred although the medians were wider than the recommended 30-ft minimum. The impact severities generated by these events, however, were such that the median crossings probably would have been prevented by NCHRP Report 350 Test Level 3 barriers.

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