Safety Hardware Research Articles

Estimating the crash responses of a vehicle from the other size vehicle tested

In the evaluation of crashworthiness of roadside safety features, full-scale impact tests are generally required according to the established test protocols. Since the tests are expensive, it is useful to predict the crash responses of a vehicle from the other size test vehicles. This concept was used in the Manual for Assessing Safety Hardware (MASH) of American Association of State Highway and Transportation Officials (AASHTO) to decide whether mid-size vehicle tests are necessary for an attenuator system design in addition to the small car and pickup truck tests. The general applicability of this procedure in the estimation of impact responses of one vehicle from the tested vehicle is studied using the crash test data of 11 crash cushions tested by the Korea Expressway Corporation Research Institute (KECRI). Each of the 11 crash cushions has two sets of test data from 1.3 and 0.9 ton vehicles tested with an impact speed of 80 or 100 km/h depending on the class of each system. Using the procedure, for each of the 11 systems, 1.3 ton crash data were transformed into the 0.9 ton crash data, then the estimated 0.9 ton crash data were compared with the 0.9 ton test data. It was found that the crash data predictions deviated from the test data, leading to overly conservative estimation of safety risk factors. The procedure was also found inapplicable in estimating crash data of a large vehicle (1.3 ton) from the test data of a small vehicle (0.9 ton). New procedure to estimate the crash data of a vehicle from the test vehicle regardless of their relative mass size was developed and the method was validated using the crash test data of 11 different crash cushions. In the new procedure developed, pivoting the velocity trace of test vehicle was utilised. The new procedure showed favourable results in estimating the crash data of a small vehicle (0.9 ton) from the crash data of a large test vehicle (1.3 ton). It can also be applied in reverse case estimation where the predicting vehicle (1.3 ton) was larger than the test vehicle (0.9 ton).

Safety Performance of G4 (1S) W-Beam Guardrails versus Cable Median Barriers on Florida's Freeways

Different roadside safety hardware including guardrails and cable barriers have been installed on freeways to prevent run-off-the-road and median crossover crashes. This article compares the safety performance of G4 (1S) strong-post W-beam guardrails and cable barriers installed in the medians on freeways in Florida. The comparison is based on the percentages of barrier and median crossovers by vehicle type and crash severity. A crash is categorized as barrier crossover crash if the errant vehicle crosses the barrier during the crash. If after crossing the barrier the errant vehicle clears the median and traverses into the opposite travel lanes, it becomes a median crossover crash. To obtain a more precise measurement of barrier performance, this study considers only crashes involving vehicles hitting a barrier. A total of 678.9 miles of freeways with G4 (1S) W-beam guardrails and 101.0 miles of freeways with cable barriers were identified. Police reports of 8,536 crashes from years 2006 to 2010 at these locations were reviewed. Z-test and odds ratio were used to compare the safety performance of cable median barriers and guardrails. Overall, guardrails performed slightly better than cable barriers in terms of barrier and median crossover crashes. However, cable median barriers were found to result in fewer severe injury crashes.

An automatically reconfigurable software-based safety system for rear-steering multi-unit vehicles

In order to introduce longer heavy vehicles with multiple articulation joints between vehicle units into the UK and other European countries, it is likely that rear steering of the vehicle units will be required to allow sufficient manoeuvrability. This has safety implications. This paper details the development of a modular and automatically reconfigurable safety system, appropriate to this safety-critical application. Details of the specification for the system, the state-chart basis for the system, the issues relating to coding within a safety system, the software and hardware interaction and the implications on the design are covered. Practical implementation of the system on the Cambridge Vehicle Dynamics Consortium’s reconfigurable long combination vehicle is outlined, and the initial test results of the system’s low-speed and high-speed steering functions and fault tolerance are presented.

Impact performance evaluation of MASH TL4 bridge barrier

Many roadside safety features such as traffic barrier systems, end treatments, crash cushions, breakaway devices, truck-mounted attenuators, and other hardware are used to achieve the highest levels of highway safety. A goal of a highway safety feature is to provide a forgiving roadway and roadside that reduces the risk of a serious accident when a vehicle leaves the roadway. Among various evaluation methods, full-scale crash test has been and will continue to be the most common method of evaluating the impact performance of safety hardware, therefore there are many countries that have the full-scale crash test procedures and evaluation criteria including the US, EU, and South Korea.The recommended procedures for the full-scale crash test of safety hardware have been developed in the US starting from Highway Research Correlation Services Circular 482 in 1962. During the subsequent decade, the evolution of roadside safety concepts, technology, and practices necessitated an update to previous recommendations. In 2009, the American Association of State Highway and Transportation Officials (AASHTO) published Manual for Assessing Safety Hardware (MASH) for the purpose of evaluating new safety hardware devices and this publication marks the first time that AASHTO has officially adopted crash-testing procedures for use in assessing roadside hardware. However, the evaluation of a bridge barrier in accordance with MASH has not been performed until 2012. Within the scope of this research, a bridge barrier system that meets the MASH criteria has been developed and evaluated, and the procedures and the results are described in this paper. The developed bridge barrier with the target safety level of TL4 is first designed using the plastic failure mechanism approach presented in AASHTO LRFD Design Specifications as a static manner and then the impact performance is pre-evaluated by the three-dimensional crash analysis software, LS-DYNA. Finally, the full-scale crash test is performed at Texas Transportation Institute for tests 4-10, 4-11, and 4-12 using 2005 Kia Rio passenger car, 2008 Dodge Ram pickup truck, and 1998 International 4700 single-unit truck, respectively. The full-scale crash test results meet the evaluation criteria presented in MASH, hence the developed bridge barrier in this research is ready for the field application.

$$\upmu \mathrm{DC}^2$$ μ DC 2 : unified data collection for data centers

Modern data centers are playing an important role in a world full of information and communication technologies (ICTs). Many efforts have been paid to build a more efficient, cleaner data center for economic, social, and environmental benefits. This objective is being enabled by emerging technologies such as cloud computing and software-defined networking (SDN). However, a data center is inherently heterogeneous, consisting of servers, networking devices, cooling devices, power supply devices, etc., resulting in daunting challenges in its management and control. Previous approaches typically focus on only a single domain, for example, traditional cloud computing for server resource (e.g., computing resource and storage resource) management and SDN for network management. In a similar context of networking device heterogeneity, network function virtualization has been proposed to offer a standard abstract interface to manage all networking devices. In this research, we take the challenge of building a suit of unified middleware to monitor and control the three intrinsic subsystems in a data centre, including ICT, power, and cooling. Specifically, we present $$\upmu \mathrm{DC}^2$$ μ DC 2 , a unified scalable IP-based data collection system for data center management with elevated extensibility, as an initial step to offer a unified platform for data center operations. Our system consists of three main parts, i.e., data-source adapters for information collection over various subsystems in a data center, a unified message bus for data transferring, and a high-performance database for persistent data storage. We have conducted performance benchmark for the key building components, namely messaging server and database, confirming that our system is scalable for a data center with high device density and real-time management requirements. Key features, such as configuration files, dynamical module loading, and data compression, enhance our implementation with high extensibility and performance. The effectiveness of our proposed data collection system is verified by sample applications, such as, traffic flow migration for load balancing, VM migration for resource reservation, and server power management for hardware safety. This research lays out a foundation for a unified data centre management in future.

Performance of the Midwest Guardrail System with Rectangular Wood Posts

Strong-post W-beam is one of the most enduring and prolific safety barriers in the world. Over the years, it has been modified and updated to improve performance. Throughout these changes, two types of guardrail posts have been used to support the rail element: W6 × 8.5 steel posts and 6-in.-wide × 8-in.-deep wood posts. Recent updates to roadside safety hardware evaluation criteria and concerns with the performance of the G4 (1S) and G4 (2W) strong-post W-beam systems have led to the need for enhanced strong-post guardrail designs. The Midwest Guardrail System (MGS) was developed to address this need and provides improved performance over previous strong-post W-beam systems. The MGS was developed and tested with steel support posts, and it was believed that the use of wood posts in the system would provide similar barrier performance. However, the effect of wood posts in the MGS was never quantified through full-scale crash testing. The objective of this study was to investigate and evaluate the performance of the MGS with rectangular posts made of southern yellow pine. This effort included a review of the performance of wood and steel guardrail posts as it pertained to the MGS, the completion of two full-scale crash tests according to the Manual for Assessing Safety Hardware (MASH) safety requirements, and a comparison of the full-scale test results with MASH safety criteria and previous steel-post and alternative species wood-post MGS tests. Finally, recommendations were developed to implement the wood-post MGS and wood posts in MGS special applications.

A Review of Spacecraft Safety: From Vostok to the International Space Station

As the U.S. manned space program begins its transition from government to commercial enterprise, the safety of the crew, ground, and general public is of paramount concern. A catastrophic accident early in NASA's Commercial Crew Development (CCDev) program could derail the nascent commercial space industry, leaving the United States wholly reliant on Russia for manned launch services. To reduce this risk, lessons learned from past space programs should be assimilated into current commercial practice. This article traces the evolution of manned spacecraft hardware safety, from Vostok to the International Space Station, with the hope that a review of yesterday's spacecraft will benefit tomorrow's space travelers.

Evaluation Process for the Hardware Safety Integrity Level

Evaluation Process for the Hardware Safety Integrity Level

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

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.

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

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.

Midwest Guardrail System without Blockouts

The Midwest Guardrail System (MGS) has been shown to provide exceptional redirective capability in standard and special applications. However, the roadway width required to install a guardrail system with a blockout is not always available. In response, a nonproprietary non-blocked MGS was developed and successfully crash tested according to the testing standards established in the Manual for Assessing Safety Hardware. This study compared results from 1100C small car and 2270P pickup truck tests for the standard (blockout) and nonblocked versions of the MGS and concluded that the standard MGS performed better than the nonblocked MGS. As a result, it is recommended that the non-blocked MGS be used only in places where roadway width is a limiting parameter. If width is not restricted, use of a blockout as designated in the design drawings of the standard MGS is still recommended.

The Application of RFID Technology in the University Library

This paper opens with an introduction of RFID technology and its application in libraries at home and abroad, discusses the advantages of RFID technology in the university library applications, and analyzes the problems of RFID technology in the university library applications from the aspects of technical standards, operating frequency, application costs, and management of the library automation system integrated and compatible hardware and software update service and safety aspects.

충격흡수시설에 대한 특정 충돌시험데이터의 확대해석

충돌해석 데이터의 확대해석 사례는 미국의 도로안전시설 지침인 MASH(Manual for Assessing Safety Hardware, AASHTO, 2009)에서 2,270 kg 픽업트럭의 충격흡수시설에 대한 충돌시험 데이터로부터 1,500 kg 중형승용차의 안전도를 계산하는 절차에 관한 내용을 최초로 소개하였다. MASH 방법에 따라 1.3 ton 차량의 충돌시험 데이터로부터 0.9 ton 차량의 충돌데이터 및 안전지수를 계산하여 0.9 ton 차량의 충돌실험 데이터와 비교하였다. 비교 결과 MASH방법으로 계산한 0.9 ton 차량의 충돌데이터 및 안전지수가 충돌실험 데이터와 큰 차이를 나타낸다는 것을 확인하였고 그 원인을 분석하여 새로운 확대해석 방법을 개발하였다. 개발된 확대해석 방법은 질량이 큰 차량(1.3 ton)의 충돌시험 데이터로부터 작은 차량(0.9 ton)의 충돌 데이터를 계산할 수 있을 뿐 아니라 작은 차량(0.9 ton)의 충돌 데이터로 부터 큰 차량(1.3 ton)의 데이터를 계산할 수 있다. 개발된 확대해석 방법은 정확도가 MASH에 비하여 월등하고 이론적인 원리가 확실하다. 본 논문은 충돌시험 데이터를 이용하여 새로운 확대해석 방법의 효율성과 정확도를 입증하고 그 원리를 규명하였다. It is found the first case of broad interpretation of the crash analysis in MASH (Manual for Assessing Safety Hardware, AASHTO, 2009) which is the guideline of roadside safety features in United States. They introduced the procedure of calculating 1,500 kg sedan safety index from the 2,270 kg pick-up truck crash test for crash cushion. First, following MASH's method, calculate 0.9 ton vehicle crash data and safety index using 1.3 ton vehicle crash test data and compare with actual 0.9 ton vehicle crash test data. results show that actual test data and the data calculated by MASH's method have great difference. Second, analyse the cause and develop new method. Proposed method can estimate not only the lighter vehicle (0.9 ton) crash data from the heavier vehicle (1.3 ton) crash test but also heavier vehicle (1.3 ton) data from lighter vehicle (0.9 ton) test. This method is superior to MASH's method and has stronger theoretical foundation. This paper proves the efficiency and the accuracy of new broad interpretation method using crash test data and investigates the principle.

The development of an enhanced finite element tire model for roadside safety hardware assessment

Various types of roadside safety hardware are deployed along highways to safely redirect or contain errant vehicles such that there is no intrusion into a hazardous area or on-coming traffic that may cause harm to the drivers or occupants. Primary factors for the crashworthiness evaluation of these hardwares include structural adequacy, occupant risk, and after-collision vehicle trajectory. Suspension characteristics of the vehicle and tires interaction with safety hardware and surface conditions could influence all these factors. Simulation efforts have resulted in increasingly better replications of crash events, but it has been noted that tire behaviors and failures are still not predicted well. This article will describe efforts to improve the finite element modeling technique of a vehicle tire. A new tire model, having the physical structure of a tire that could influence the nature of operational and crash-induced loading of the tire is presented. Techniques for characterizing the tire material and suspension properties are discussed. Correlation between the simulation results and the full-scale crash testing data is discussed. Measures for assessing occupant injury risk and occupant impact severity are evaluated for both sets of data. Finally, preliminary results using the new tire model in vehicle impact simulations to investigate the effect on vehicle stability, subject to variations in impact conditions such as speed and angle, are presented.

Transition of Temporary Concrete Barrier

The objective of this research was to design a transition from temporary concrete barriers to a permanent concrete barrier for median applications. The researchers at Midwest Roadside Safety Facility utilized a combination of free-standing and tied-down Kansas temporary concrete barriers and a dual-nested thrie beam for the transition to the single-slope permanent barrier as well as a transition cap. Two full-scale vehicle crash tests were performed on the system. Evaluation of the approach transition required testing at two Critical Impact Point (CIP) locations. The first tests was performed using a half-ton pickup truck that impacted the temporary barriers 1,432 mm upstream from the permanent barrier, at a speed and angle of 100.7 km/h and 24.7 degrees, respectively. The second crash test was also performed using a half-ton truck that impacted the temporary barriers 16.6 m upstream from the permanent barrier, at a speed and angle of 100.1 km/h and 26.2 degrees, respectively. Both tests were conducted and reported in accordance with requirements specified in the Manual for Assessing Safety Hardware (MASH) and were determined to be acceptable according to the Test Level 3 (TL-3) evaluation criteria.

Concrete Roadside Barrier Anchorage Details for 5-in., Cast-in-Place Decks on Prestressed Beams

The Texas Department of Transportation commonly builds bridge spans with adjacently framed, prestressed box beams and slab beams and makes them composite with a 5-in.-thick, concrete, cast-in-place deck (CIPD). The presence of a cast-in-place, concrete overlay allows use of more favorable empirical, live-load distribution equations, which results in more efficient bridge spans. This 5-in.-thick CIPD offers limited depth for anchorage of rail reinforcement. AASHTO Load and Resistance Factor Design Bridge Design Specifications has a limiting hook development length of 6 in. for a No. 4 rail anchorage. With a 5-in. deck thickness and a 6-in. minimum required development length, the rail anchorage reinforcement must be cast in the pretensioned beams to meet specification requirements for rail anchorage strength. This need has made it difficult to ensure adequate development of the rail anchorage reinforcement. The objective of the study reported here, therefore, was to develop barrier anchorage details that would meet the AASHTO Manual for Assessing Safety Hardware (MASH) evaluation criteria, minimize damage to the concrete barrier profile and CIPD, and prevent delamination of the CIPD from the precast beams, which was witnessed in a research project performed at Texas Transportation Institute. The anchorage modifications were evaluated successfully under the Manual for Assessing Safety Hardware Test 3–11 and were considered suitable for roadways with traffic conditions appropriate for Testing Level 3 safety hardware.

Collision behaviour of double W-beam transition

Vehicle collisions result in many injuries and fatalities every year all around the world. A significant number of those incidents occur outside the roadway, partly owing to the incompatibility between the roadside safety hardware and impacting vehicles. Although the purpose of using roadside safety hardware is safely to contain impacting vehicles and reduce impact severity, use of inadequate safety hardware can have serious consequences. In this study, the crash behaviour of a currently used double W-beam transition barrier was analysed and its adequacy is evaluated using a series of five vehicular impacts. Finite element simulations were used to perform the analysis, and a full-scale crash test result was used to validate the finite element models used in the study. Results of the analysis predict that double W-beam transition can safely contain and redirect vehicles ranging from compact automobiles to high centre of gravity heavy trucks up to 10,000 kg in mass. Occupant injury risk values obtained from all five cases are also calculated and presented. Further use of computational tools in safety evaluation of the existing roadside safety hardware is strongly recommended.

Minimum Rail Height and Design Impact Load for Longitudinal Barriers that Meet Test Level 4 of Manual for Assessing Safety Hardware

In 2009, the Manual for Assessing Safety Hardware (MASH) was adopted as an updated replacement of NCHRP Report 350. Under MASH, the impact severity of Test Level 4 (TL-4) (Test 4–12) was increased by 56%. Test vehicle mass was increased from 17,640 to 22,050 lb. Impact speed was increased from 50 to 56 mph. Although this is a significant increase in the amount of lateral energy imparted to the barrier, the 54-kip design impact load currently suggested by the AASHTO load and resistance factor design (LRFD) bridge specifications has not been updated to meet MASH TL-4 requirements. Similarly, the AASHTO LRFD specifications require all TL-4 railings to have a minimum height of 32 in. However, because of the increase in test vehicle mass and impact velocity under MASH, the minimum height for TL-4 railings is expected to be greater than 32 in. This height was verified by a recent unsuccessful MASH Test 4–12 of a New Jersey profile rigid concrete barrier 32 in. tall. The research presented in this paper used finite element analysis and subsequent crash testing to determine the minimum rail height for MASH TL-4 impact conditions. The researchers also determined the appropriate lateral impact design load for use with AASHTO LRFD bridge specifications for the design of TL-4 bridge rails.

Comparison of Crash Test and Simulation Results for Impact of Silverado Pickup into New Jersey Barrier under Manual for assessing Safety Hardware

The National Crash Analysis Center (NCAC) at the George Washington University simulated the crash of a 2,270-kg Chevrolet Silverado pickup truck into a standard 32-in. New Jersey shape concrete barrier under the requirements of Test 3–11 of the Manual for Assessing Safety Hardware (MASH). The new, detailed finite element (FE) model for the Chevrolet Silverado was used as the surrogate for the MASH 2270P test vehicle. An FE model of the New Jersey barrier was drawn from the array of NCAC hardware models. The primary objective of this analysis was to simulate the crash test conducted to evaluate how this commonly used, NCHRP 350–approved device would perform under the more rigorous MASH crashworthiness criteria. A secondary objective was to use newly developed verification and validation (V&V) procedures to compare the results of the detailed simulation with the results of crash tests undertaken as part of another project. The crash simulation was successfully executed with the detailed Silverado FE model and NCAC models of the New Jersey concrete barrier. Traditional comparisons of the simulation results and the data derived from the crash test suggested that the modeling provided viable results. Further comparisons employing the V&V procedures provided a structured assessment across multiple factors reflected in the phenomena importance ranking table. Statistical measures of the accuracy of the test in comparison with simulation results provided a more robust validation than previous approaches. These comparisons further confirmed that the model was able to replicate impacts with a 2270P vehicle, as required by MASH.

Low-Cost Median Barrier Gate

Median barriers are commonly used to separate opposing lanes of traffic on divided highways and to separate managed lanes from general purpose lanes. Concrete median barriers (CMBs) are often preferred on urban freeways with narrow medians because of their minimal deflection and low maintenance. However, long, continuous runs of CMBs limit access of emergency and maintenance vehicles to the other side of a roadway or a managed lane. Implementation of crashworthy median barrier gates at these locations can maintain the desired level of median protection for motorists while offering improved cross-median access for emergency and maintenance vehicles. A new median barrier gate was developed and crash tested. The gate spans a 30-ft opening in a CMB and consists of two vertically stacked 12- x 12- x ¼-in. steel tubes connected to steel end brackets with 2¼-in. diameter steel pins. The gate is economical to fabricate and install. It can be manually operated by a single person and is designed to accommodate reversible traffic flow on both sides of the median and be operable in both directions on each end. The median barrier gate satisfies the criteria for impact performance of Test Level 3 of the Manual for Assessing Safety Hardware and is considered suitable for implementation on divided highways at locations where cross-median access is desired.