Standard Midwest Guardrail System Placed at 1V:2H Slope Break Point or with Omitted Post

2017 ◽  
Vol 2638 (1) ◽  
pp. 65-76
Author(s):  
Karla A. Lechtenberg ◽  
Robert W. Bielenberg ◽  
Scott K. Rosenbaugh ◽  
Ronald K. Faller ◽  
John D. Reid
Keyword(s):  
High Speed ◽  
Break Point ◽  
The United States ◽  
Safety Performance ◽  
Performance Criteria ◽  
Safety Hazards ◽  
Long Span ◽  
Level 3 ◽  
Occurrence State ◽  
And Behavior

State departments of transportation (DOTs) throughout the United States commonly use W-beam guardrail systems to keep errant vehicles from leaving high-speed roadways and encountering safety hazards adjacent to the roadway edge, such as steep roadside slopes. Additionally, although W-beam guardrail is used to protect errant vehicles from safety hazards along the roadways, obstructions at post locations within a run of guardrail are a common occurrence. State DOTs wanted to evaluate the standard Midwest Guardrail System (MGS) for use in these instances. First, the standard MGS with 6-ft (1,829-mm) W6 × 8.5 (W152 × 12.6) steel posts spaced at 75 in. (1,905 mm) placed at the slope break point of a 1V:2H slope was successfully crash tested and evaluated according to the Test Level 3 (TL-3) safety performance criteria presented in the Manual for Assessing Safety Hardware (MASH). Subsequently, the standard MGS with one omitted post, which created an unsupported span of 12.5 ft (3.8 m), was full-scale crash tested, and it satisfied the MASH TL-3 safety performance criteria. Because multiple variations of the MGS system have been developed for special applications, recommendations for the omission of a post or installation on a steep slope will vary depending on the nature and behavior of the application. The safety performance of various MGS configurations and special applications was compared. Implementation guidance was then given about the use of the MGS placed at the slope break point and omitting a post in the MGS with MGS special applications. These special applications included terminals and anchorages, MGS stiffness transition to thrie beam approach guardrail transitions, MGS long-span system, MGS adjacent to 1V:2H fill slopes, MGS on 1V:8H approach slopes, MGS in combination with curbs, wood post MGS, and MGS without blockouts.

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.

Midwest Guardrail System Adjacent to a 2:1 Slope

2008 ◽  
Vol 2060 (1) ◽  
pp. 74-83 ◽  
Author(s):  
Karla A. Polivka ◽  
Dean L. Sicking ◽  
Ronald K. Faller ◽  
Robert W. Bielenberg
Keyword(s):  
Performance Evaluation ◽  
High Speed ◽  
Evaluation Criteria ◽  
Break Point ◽  
Safety Performance ◽  
National Highway ◽  
The Cost ◽  
Steep Slopes ◽  
Economical Alternative ◽  
Highway System

A W-beam guardrail is often used to protect motorists from steep roadside slopes adjacent to high-speed roadways. Although previously designed systems have demonstrated acceptable safety performance, the long posts and half-post spacing have proven to be costly and introduce maintenance challenges. Using longer posts is more economical to users than having a system with posts installed at half-post spacing. Furthermore, the improved redirective capacity of the Midwest Guardrail System (MGS) provides the opportunity to eliminate the need for half-post spacing and thereby greatly reduces the cost of placing a barrier at the slope break point. A stiffened version of the MGS was developed for use adjacent to steep roadside slopes. The new design incorporates 2,743-mm (9-ft) long posts with 1,905-mm (75-in.) spacing. With the top of the W-beam mounted at a height of 787 mm (31 in.), this guardrail was successfully crash tested according to the currently proposed NCHRP Report 350 Update safety performance evaluation criteria. Hence, the stiffened MGS guardrail design with full post spacing is acceptable for use on the National Highway System. This new guardrail design will provide a safe and economical alternative for use along highways with steep slopes very close to the travelway.

Review of Live Load Impact Factor for Existing Truss Railroad Bridges in the United States

2013 ◽  
Author(s):  
David W. Jacobs ◽  
Ramesh B. Malla
Keyword(s):  
Impact Factor ◽  
Energy Efficient ◽  
High Speed ◽  
The United States ◽  
Live Load ◽  
Railroad Bridges ◽  
Long Span ◽  
Railway Engineering ◽  
Significant Effort ◽  
Load Impact

The current American Railway Engineering and Maintenance-of-Way Association (AREMA) Manual provides live load impact formulas for the design of steel railroad bridges. The only variable in those formulas is span length and do not include other parameters that bridge engineers know affects live load impact factor. Years of use in practice and research have shown that these formulas are reliable, safe and simple to apply, though often very conservative. In order to make the nation’s transportation more efficient and energy efficient, a significant effort is underway in the U.S. to enhance its railroad infrastructures. Bridges built before the 1950s, many of which are still in service, were designed to sustain the effects of steam engine hammer blow, and consequently slow speed. Yet, most of these bridges may not be replaced and may be required to carry high speed passenger equipment. This raises the question of what effects higher speed trains will have on old, long span truss steel bridges. This paper presents finding from the detail literature review on the current live load impact factor on truss railroad bridges and its implication to the future.

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.

Influence of Random Multi-Point Seismic Excitations on the Safety Performance of a Train Running on a Long-Span Bridge

2020 ◽  
Vol 20 (04) ◽  
pp. 2050054
Author(s):  
Wei Wang ◽  
Yahui Zhang ◽  
Huajiang Ouyang
Keyword(s):  
High Speed ◽  
Ground Motions ◽  
Time History ◽  
Arma Model ◽  
Safety Performance ◽  
Seismic Excitations ◽  
Dynamic Reliability ◽  
Running Safety ◽  
Long Span ◽  
Long Span Bridge

The increasing use of bridges in high-speed railway (HSR) lines raises the possibility of train derailment on bridges under seismic excitations. In this paper, the influence of random multi-point earthquakes on the safe running of a train on a long-span bridge is studied in terms of the dynamic reliability, considering spatial seismic effects, and randomness of ground motions and train locations. The equations of motion for the train and the track/bridge as time-invariant subsystems under earthquakes are established, separately. The two subsystems are connected via the wheel–rail interface, for which a nonlinear contact model and detachment are considered. The time-history samples of nonstationary multi-point random earthquakes considering wave passage effects and incoherence effects are generated by the autoregressive moving average (ARMA) model. The ground motions are imposed on the bridge support points in terms of displacement and velocity. The train location at the time of earthquake is considered a uniformly distributed random variable. The running safety reliability of a train moving on a long-span bridge under earthquakes is determined by combining subset simulation (SS) with a prediction-based iterative solution method. Under different seismic components, train speeds, apparent seismic wave velocities and seismic intensities, the most unfavorable train location intervals are determined, which provides a reference for the safety performance assessment of trains traveling on bridges under earthquakes. Numerical results show that the influence of the lateral seismic component on the wheel derailment coefficient (WDC) is greater than the vertical seismic component, and the earthquake that occurs before the train’s arrival at 70% length of the bridge will significantly reduce its running safety.

Design and Testing of Tie-Down Systems for Temporary Barriers

2003 ◽  
Vol 1851 (1) ◽  
pp. 83-94 ◽  
Author(s):  
Bob W. Bielenberg ◽  
Ronald K. Faller ◽  
John D. Reid ◽  
John R. Rohde ◽  
Dean L. Sicking
Keyword(s):  
Bridge Deck ◽  
Safety Performance ◽  
Performance Criteria ◽  
Crash Test ◽  
Concrete Bridge ◽  
Safety Standards ◽  
Vehicle Crash ◽  
Rigid Attachment ◽  
Level 3 ◽  
Concrete Bridge Deck

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.

Injuries and Occupational Safety

2017 ◽  
Author(s):  
Dawn N. Castillo ◽  
Timothy J. Pizatella ◽  
Nancy A. Stout
Keyword(s):  
United States ◽  
Ionizing Radiation ◽  
Occupational Safety ◽  
Occupational Injury ◽  
Occupational Injuries ◽  
Mechanical Energy ◽  
The United States ◽  
Hierarchical Approach ◽  
Safety Hazards ◽  
Injury Control

This chapter describes occupational injuries and their prevention. It describes in detail the causes of injuries and epidemiology of injuries. Occupational injuries are caused by acute exposure in the workplace to safety hazards, such as mechanical energy, electricity, chemicals, and ionizing radiation, or from the sudden lack of essential agents, such as oxygen or heat. This chapter describes the nature and the magnitude of occupational injuries in the United States. It provides data on risk of injuries in different occupations and industries. Finally, it discusses prevention of injuries, using a hierarchical approach to occupational injury control.

The Interplay of Developing Morality and Gender Attitudes

2020 ◽  
pp. 724-745
Author(s):  
Rebecca S. Bigler ◽  
Lynn S. Liben
Keyword(s):  
Psychological Theory ◽  
The United States ◽  
Gender Nonconformity ◽  
Gender Attitudes ◽  
Future Research ◽  
Policy And Practice ◽  
Ethical Policy ◽  
History Of ◽  
And Gender ◽  
And Behavior

Morality and gender are intersecting realms of human thought and behavior. Reasoning and action at their intersection (e.g., views of women’s rights legislation) carry important consequences for societies, communities, and individual lives. In this chapter, the authors argue that children’s developing views of morality and gender reciprocally shape one another in important and underexplored ways. The chapter begins with a brief history of psychological theory and research at the intersection of morality and gender and suggests reasons for the historical failure to view gender attitudes through moral lenses. The authors then describe reasons for expecting morality to play an important role in shaping children’s developing gender attitudes and, reciprocally, for gender attitudes to play an important role in shaping children’s developing moral values. The authors next illustrate the importance and relevance of these ideas by discussing two topics at the center of contentious debate in the United States concerning ethical policy and practice: treatment of gender nonconformity and gender-segregated schooling. The chapter concludes with suggestions for future research.

Intersectionality, Black Youth and Political Activism

2020 ◽  
Author(s):  
Patricia Hill Collins
Keyword(s):  
Young People ◽  
Social Inequalities ◽  
Coming Of Age ◽  
Black Youth ◽  
Political Activism ◽  
The United States ◽  
Gender And Sexuality ◽  
Youth Activism ◽  
The Political ◽  
And Behavior

For youth who are Black, Indigenous, female, or poor, coming of age within societies characterized by social inequalities presents special challenges. Yet despite the significance of being young within socially unjust settings, age as a category of analysis remains undertheorized within studies of political activism. This essay therefore draws upon intersectionality and generational analyses as two useful and underutilized approaches for analyzing the political agency of Black youth in the United States with implications for Black youth more globally. Intersectional analyses of race, class, gender, and sexuality as systems of power help explain how and why intersecting oppressions fall more heavily on young people who are multiply disadvantaged within these systems of power. Generational analysis suggests that people who share similar experiences when they are young, especially if such experiences have a direct impact on their lives, develop a generational sensibility that may shape their political consciousness and behavior. Together, intersectionality and generational analyses lay a foundation for examining youth activism as essential to understanding how young people resist intersecting oppressions of racism, heteropatriarchy, class exploitation, and colonialism.

Sign in / Sign up

Export Citation Format

Share Document