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Portable concrete barriers (PCBs) are commonly used to protect work-zone personnel and to shield motorists from hazards in construction areas. It is not uncommon to encounter longitudinal gaps within PCB installations resulting from the practice of constructing and connecting the barriers from different ends during setup or contractor operations. Longitudinal gaps can also be created by tensioning issues following an impact event. These gaps can range from 6 in. to a full barrier segment length of 12.5 ft. Longitudinal gaps between adjacent installations of PCB systems pose a serious safety concern for the errant motorist. Therefore, a need existed to develop a treatment capable of shielding the longitudinal gaps that occur between adjacent installations of PCB systems. In this research, design concepts for the gap-spanning hardware were conceived, and two design concepts were selected for further investigation and refinement through LS-DYNA computer simulation. Based on simulation results and input from the Midwest Pooled Fund Program member states, the design concept utilizing nested thrie-beam spanning the gap was chosen for full-scale crash testing under Manual for Assessing Safety Hardware 2016 (MASH 2016). Two tests were conducted to MASH test no. 3-11 to evaluate the length of need of the system, as well as the transition from the gap-spanning hardware to the PCBs. In both tests, the 2270P vehicle was contained and safely redirected. Recommendations are provided for system implementation and future installation with current PCB systems.

Since mid-2015, there has been an increasing number of chicken samples that are positive for infectious bronchitis virus (IBV) in a screening PCR but which do not show positive results in any established, variant-specific PCR tests (793B, QX, D1466, Massachusetts, D274, Italy 02, Arkansas, Variant 2, Q1). Partial sequencing of the viral genome of those samples shows great similarities, but nucleotide similarity in the S1 gene is only about 57%-61% when compared to any other known GI-GVII IBV genotype and lineage. With nucleotide identity in the S1 gene of approximately 80%, the closest related strain in the National Center for Biotechnology Information database (as of March 15, 2020) is the North American PA/1220/98 isolate (AY789942) designated as a unique variant by ValastroIB80—un nuevo genotipo del virus de la bronquitis infecciosa (GVIII). Desde mediados del 2015, ha habido un número creciente de muestras de pollo que resultan positivas para el virus de la bronquitis infecciosa (IBV) por la detección mediante PCR de escrutinio, pero que no muestran resultados positivos en ninguna prueba de PCR específica para las variantes establecidas (793B, QX, D1466, Massachusetts, D274, Italia 02, Arkansas, variante 2, Q1). La secuenciación parcial del genoma viral de esas muestras muestra grandes similitudes, pero la similitud de nucleótidos en el gene S1 es solo del 57% al 61% en comparación con cualquier otro genotipo y linaje GI-GVII conocidos del virus de bronquitis. Con una identidad de nucleótidos en el gene S1 de aproximadamente el 80 %, la cepa relacionada más cercana en la base de datos del Centro Nacional de Información Biotecnológica (al 15 de marzo de 2020) es el aislamiento norteamericano PA/1220/98 (AY789942) designado como variante única por Valastro

Passenger vehicles in Manual for Assessing Safety Hardware (MASH) crash testing are required to be representative of the modern vehicle fleet and practical worst-case impact scenarios. The objective of this paper was to identify potential updates for standard test vehicle selection criteria for MASH as well as develop a preferred strategy for performing future standard test vehicle reviews. Representative vehicles were documented using sales data, and registration and crash data were observed to validate the primary use of sales data. Curb weights were plotted against cumulative market share of new vehicle sales to identify the 5th and 95th percentile “practical worst-case” weights of 2,800 lb and 5,850 lb, respectively, consistent with MASH philosophy. Suitable test vehicle options were found at the 5th percentile weight; however, a pickup near the 92.5 percentile weight (5,400 lb) was recommended to ensure vehicles are both representative of the fleet and obtainable for crash sites. MASH test vehicle specifications were recommended based on a review of geometrical and inertial properties of candidate vehicles near these target weights. Potential mid-size test vehicles were also explored, and four vehicle classes (two mid-size car and two crossover utility vehicle [CUV] classes) were identified as test vehicle candidates. Research on vehicle impact behavior of mid-size cars and CUVs are desired to determine impact behavior of each vehicle with different roadside hardware. Future revisions to MASH test vehicle selection criteria were outlined and should use analysis and attributes of new vehicle sales.

A new, side-mounted, steel beam-and-post bridge rail was designed, crash tested, and evaluated according to safety performance guidelines included in the American Association of State Highway and Transportation Officials Manual for Assessing Safety Hardware (MASH) for Test Level 4 (TL-4). The new bridge rail system was designed to be compatible with multiple bridge decks, including cast-in-place concrete slabs and prestressed box beams. Additionally, the bridge rail was designed to remain crashworthy after roadway overlays up to 3 in. thick. The bridge rail was designed and optimized based on strength, installation cost, weight per foot, and constructability. The new bridge rail consisted of three rectangular steel tube rails supported by standard steel cross section, W6 × 15 steel posts spaced at 8 ft on-center. The upper rail was a 12 × 4 × ¼ in. hollow structural section (HSS) steel tube, and the lower two rails were 8 × 6 × ¼ in. HSS steel tubes. The top mounting heights for the upper, middle, and lower rails were 39 in., 32 in., and 20 in. above the surface of the deck, respectively. A new, side-mounted, post-to-deck connection was also developed that incorporated HSS steel spacer tubes that offset the posts 6 in. from the bridge deck and aligned the face of the bridge rail with the edge of the deck. Thus, the traversable width of the bridge was maximized. Three full-scale crash tests corresponding to the MASH TL-4 testing matrix were performed on the new bridge rail. All three crash tests successfully contained and redirected the vehicles and satisfied all MASH evaluation criteria.

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.

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.

Portable concrete barriers (PCBs) are often used in applications in which limited deflection is desired during vehicle impacts, such as bridge decks and work zones. In an earlier study, a reduced-deflection, stiffening system was configured for use with non-anchored, F-shape PCBs and was successfully crash tested under Manual for Assessing Safety Hardware (MASH) safety performance criteria. However, details and guidance for implementing this barrier system outside the length-of-need, including within transitions to other barrier systems, were not provided. The focus of this study was to develop a crashworthy transition design between the reduced-deflection, F-shape PCB system to free-standing, F-shape PCB segments using engineering analysis and LS-DYNA computer simulation. First, the continuous steel tubes in the reduced-deflection system were tapered down to the surface of the free-standing PCB segments to reduce the potential for vehicle snag. In addition, steel tube spacers were added at the base of the two joints upstream from the reduced-deflection system to increase the stiffness of adjacent free-standing PCBs. Simulations were performed to determine the critical impact points for use in a full-scale crash testing program. It was recommended that three full-scale crash tests be conducted, two tests with a 2270P pickup truck vehicle and one test with an 1100C passenger car, to evaluate the proposed design system with impacts at the recommended critical impact points.

A retrofit stiffening mechanism was developed for use in reducing the deflection of an F-shape portable concrete barrier (PCB) system without requiring anchorage of the barrier segments to the road...

Short-radius guardrail systems were developed to protect motorists from hazards at intersecting roadways. For some intersecting roadway locations, the use of a curved system with radii larger than ...

Experimental and numerical investigations were conducted on impact performance and deflection of precast, portable concrete construction barrier, referred to as a portable concrete barrier (PCB), with a free-standing and a box-beam stiffened configuration. A 61-m long PCB system, consisting of ten 6.1-m long PCBs, was initially evaluated with two full-scale crash tests in a free-standing configuration and a box-beam stiffened configuration according to safety performance guidelines in Manual for Assessing Safety Hardware (MASH) 2016 for Test Level 3 (TL-3). Finite element models were developed using LS-DYNA and validated with these crash tests to ensure their feasibility to estimate barrier deflections and evaluate safety performance. The validated numerical models were used to conduct numerical simulations and investigate effects of concrete constitutive models and barrier length on the performance of PCB system with a box–beam stiffened configuration. Numerical results provided information on the selection and use of concrete constitutive models for evaluation of reinforced concrete barrier impact performance. Furthermore, the reduced-length analysis demonstrated that a reduction in the total system length resulted in decreased dynamic barrier deflection during impact events, as the ends of each system were pinned. This reduced-length analysis provided useful guideline on PCB system design and application for traffic control plan.

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.

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.

A new, high-containment longitudinal barrier was designed to reduce the acceleration imparted to passenger vehicles during impacts and to be restorable and reusable. Elastomer support posts were designed to translate laterally and absorb energy when struck and then to restore to their initial position after impact events. A hybrid concrete beam and steel tube combination rail was optimized to minimize weight, provide sufficient structural capacity, maintain a height to contain and redirect single-unit trucks, and prevent passenger vehicles from snagging on the posts. Three full-scale vehicle crash tests were conducted according to the Manual for Assessing Safety Hardware ( MASH) Test Level 4 (TL-4) safety performance requirements on a barrier 240 ft long with nominal height of 38⅝ in. In the Safer for Highway Test 1 (SFH-1), a 5,021-lb pickup truck was redirected with minimal damage to the barrier. The peak lateral acceleration was reduced 47% compared with similar impacts on rigid barriers. In the SFH-2 test, a 2,406-lb small car was redirected by the barrier, and the peak lateral acceleration was reduced 21%compared with similar impacts on rigid barriers. In the SFH-3 test, a 21,746-lb single-unit truck was successfully contained and redirected, resulting in only minor damage to the concrete rail. Therefore, the barrier met all the MASH TL-4 safety performance criteria. The paper provides recommendations about the performance, future design refinements, and installation requirements of the barrier.

Poles are regularly placed along highways and are used to support signs, lights and electrical lines. The Midwest Guardrail System (MGS) is a standard W-beam guardrail system used throughout the United States to redirect vehicles that leave the roadway away from dangerous roadside obstacles, like ravines, water hazards, and bridge piers. Placing poles near a guardrail may affect its ability to safely contain and redirect vehicles. The compatibility of poles placed in the proximity of the MGS is studied using nonlinear finite element analysis. Computer simulations were conducted with vehicles impacting the MGS with varying lateral pole offsets between the back of the system and the front face of the pole, and varying longitudinal pole location from being placed directly behind a post to directly behind the unsupported rail half-way between posts. Results show that poles placed within 16 inches behind the MGS may cause concern in regard to acceptable crash test performance for guardrail systems. Additional simulations and full-scale crash testing is required before guidelines can be recommended.

A new W-beam guardrail system for use on low-fill culverts was developed and evaluated. The system was adapted from the Midwest Guardrail System (MGS) bridge railing for attachment to the outside face of culvert headwalls. Four attachment concepts were developed and evaluated through dynamic component testing. Both lateral and longitudinal impacts were conducted on the design concepts while mounted to a concrete culvert headwall. The resultant damage from each test was confined to post bending. Although all four designs prevented damage to the socket assembly and culvert headwall, the top-mounted, single-anchor design and the side-mounted design were recommended for use on the basis of ease of fabrication and installation. The new W-beam guardrail system for attachment to low-fill culverts was designed with multiple advantages over current culvert treatments. The guardrail system mounts to the outside face of the headwall. Thus it minimizes intrusion over the culvert and maximizes the traversable roadway width. The barrier has an unrestricted system length and does not require a transition when attached to a standard MGS. The attachment configurations were designed with epoxy anchors to enable system installment on new or existing culverts. Finally, implementation guidance was provided for new system installations.

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.

Previously, the Steel and Foam Energy Reduction (SAFER) barrier system was successfully developed and crash tested for use in high-speed racetrack applications for the purpose of reducing the severity of racecar crashes into permanent, rigid, concrete containment walls. The SAFER barrier has been implemented at all high-speed oval race tracks that host events from NASCAR's top three race series and IRL's top series. However, there are a number of racetrack facilities in the United States that use temporary concrete barriers as a portion of the track layout during races. These barriers are typically used on race tracks to shield openings or protect portions of the infield. Some of these temporary barrier installations are in areas where current safety guidance would recommend treatment with the SAFER barrier. Thus, a system was successfully designed, tested, and evaluated for a system targeted towards the most pressing need in the US motorsports industry, a system for spanning openings between rigid concre...

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 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.

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.

The research study described herein developed an economical method for terminating and anchoring the upstream end of temporary concrete barrier systems. The termination and anchorage system was designed for use with the Kansas F-shape temporary concrete barrier design that is currently used by several states participating in the Midwest Pooled Fund Program. These efforts were performed in accordance with the Test Level 3 guidelines found in the Manual for Assessing Safety Hardware 2008. Criteria governing the design of the termination and anchorage system included development of adequate anchor loads over a finite deflection in order to limit peak loads, mitigation of vertical rotation and tipping of the end barrier about its longitudinal axis, and employing existing roadside safety hardware in the design to limit state hardware inventories. The termination and anchorage system allowed for a significant reduction in the number of barrier segments required upstream from the length of need and for use in anchoring a free-standing TCB system. The anchorage system was configured to effectively constrain the end of the TCB system for impacts as far upstream as the first anchored barrier segment. Full-scale crash testing demonstrated that the impacting vehicle was safely and smoothly redirected, and the test was judged acceptable according to the Test Level 3 safety criteria set forth in the Manual for Assessing Safety Hardware 2008.

A new, low-cost bridge railing was designed to be compatible with the Midwest Guardrail System (MGS). The barrier system was configured to reduce bridge deck width and its associated cost. Several concepts for an energy-absorbing bridge post were developed and tested; the concepts included strong-post designs with plastic hinges and weak-post designs with bending near the bridge deck attachment. The final railing concept incorporated S3 × 5.7 (S76 × 8.5) steel posts housed in a tubular bracket placed at the outside vertical edge of the deck and anchored to its top and bottom with one through-deck bolt. The W-beam rail section was attached to the posts with a bolt that was designed to fracture during an impact event. Two full-scale crash tests were performed in accordance with the Test Level 3 impact conditions provided in the Manual for Assessing Safety Hardware. The bridge rail system met all safety performance criteria for both the small car and pickup truck crash tests. Barrier VII computer simulations, in combination with the full-scale crash testing programs for the bridge railing and MGS, demonstrated that a special-approach guardrail transition was unnecessary.

Nail-laminated timber deck bridges represent an economical and convenient solution for rural low-volume roads, but a need exists to develop effective railing systems for this type of roadway structure. This paper describes the development of two bridge railings that are specifically designed for transverse nail-laminated timber deck bridges and that meet the requirements for Test Level 1 (TL-1) of the Manual for Assessing Safety Hardware (MASH) and TL-2 of NCHRP Report 350. The design for each of the railing systems was based on retrofit modifications applied to existing bridge railings that were previously successfully tested: one for a longitudinal glue-laminated timber deck and the other for a transverse glue-laminated timber deck. For both railing systems, component testing was performed to investigate the behavior of the proposed design and the potential advantage of various solutions. A full-scale crash test assessed the safety performance of the TL-1 curb-type railing under the new MASH criteria, while dynamic component tests were deemed sufficient for the assessment of the steel railing under TL-2 conditions for NCHRP 350.

Design of high-performance concrete barriers for heavy vehicles has advanced little in recent years. Barrier improvements were needed in terms of design aesthetics, safety performance, and economy. Advancement was deemed necessary for improved barrier geometry design to reduce vehicle instability and the potential for occupant head slap on the barrier, improved understanding of impact loads for heavy vehicles and use of these loads to optimize barriers, and improved barrier aesthetics. This paper describes the development of two NCHRP Report 350 Test Level 5 (TL-5) barriers that address these needed advancements. First, a TL-5 open concrete bridge rail was designed with a focus on determining accurate impact loads and providing a barrier geometry with improved safety and aesthetics. Next, a TL-5 concrete median barrier was developed through rigorous analysis of barrier shape options to determine the safest and most economic shape. Structural design of the barrier was also optimized to minimize cost while meeting the design loads for heavy vehicles. The open concrete bridge rail and the concrete median barrier were successfully full-scale crash-tested according to the TL-5 safety requirements set forth in NCHRP Report 350. These designs represent a major advancement in the safety and economy of high-performance concrete barriers.

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.

This paper presents findings of an investigation of the safety performance of culvert safety grates when installed on slopes as steep as 3:1, as recommended by the AASHTO Roadside Design Guide (RDG). LS-DYNA modeling was used to identify critical impact conditions for roadside culvert grates installed on 3:1 slopes. Two full-scale vehicle crash tests were conducted under the guidelines of NCHRP Report 350 on a 6.4- × 6.4-m (21-×21-ft) culvert safety grate installed on a 3:1 slope. The full-scale crash tests demonstrated that the AASHTO RDG recommended safety grates provide acceptable safety performance when installed on 3:1 slopes.

In many crashworthiness applications the tire and suspension play a significant role in the behavior of the vehicle during the crash. For many of those applications, that role can be effectively modeled with simplified models of those parts. However, in some crash events the tire and suspension need to be modeled in great detail in order to accurately capture the response of the vehicle. To better simulate such events, a new tire model was developed that takes into account the major components of a tire, including the tread, sidewall, steel beads, steel belts and body plies. Laboratory testing was performed in order to help validate the tire model. LS-DYNA, a nonlinear finite element analysis code, was used as the simulation tool. Some important details about properly pressurizing the tire and using relative damping to control excessive tread vibrations were discovered during the research. A significant effort was made to keep the number of elements in the model as low as possible without sacrifi...

On the basis of the proposed changes to the NCHRP Report 350 guidelines, NCHRP Project 22-14(2) researchers deemed it appropriate to first evaluate two strong-post W-beam guardrail systems before finalizing the new crash testing procedures and guidelines. For this effort, the modified G4(1S) W-beam guardrail system and the Midwest Guardrail System (MGS) were selected for evaluation and comparison. Five full-scale vehicle crash tests were performed with the two longitudinal barrier systems, in accordance with the Test Level 3 (TL-3) requirements presented in the NCHRP Report 350 Update. For the modified G4(1S) testing program, two 2,270-kg pickup truck vehicles (2270P vehicles) were used: one 3/4-ton, two-door vehicle and one 1/2-ton, four-door vehicle. For the MGS testing program, two 2,270-kg pickup truck vehicles (2270P vehicles) and one 1,100-kg small-car vehicle (an 1100C vehicle) were used, with both pickup truck configurations being evaluated. On the basis of several findings, the NCHRP Project 22-14(2) researchers determined that the 1/2-ton, four-door pickup truck was better suited for use as a surrogate light truck test vehicle than the 3/4-ton, two-door pickup truck. The modified G4(1S) W-beam guardrail system, mounted at the top rail height of 706 mm, provided acceptable safety performance when it was crashed into by the 1/2-ton, four-door pickup truck vehicle, thus meeting the proposed TL-3 requirements presented in the NCHRP Report 350 Update. Testing of the modified G4(1S) W-beam guardrail system was not successful with a 3/4-ton, two-door pickup truck under the TL-3 impact conditions. The MGS was found to meet the TL-3 criteria presented in the NCHRP Report 350 Update for Test Designations 3-10 and 3-11. Satisfactory safety performance was observed with the MGS with both the 1/2-ton, four-door and 3/4-ton, two-door pickup truck vehicles.

The Midwest guardrail system (MGS), developed at the Midwest Roadside Safety Facility, was designed to improve the performance of traditional strong-post, W-beam guardrail systems. These improvements include decreasing the potential for rollover with high center-of-gravity vehicles, decreasing the potential for rail rupture at the splice locations, and decreasing the sensitivity of the system to the installation rail height. However, safe guardrail termination options for the MGS must be developed before the system can be implemented on the roadside. Two end terminal designs, the sequential kinking terminal (SKT) and the flared energy-absorbing terminal (FLEAT), were partially redesigned and crash tested in conjunction with the MGS according to NCHRP Report 350 criteria. The new versions of the terminals were named the SKT-MGS and the FLEAT-MGS to designate them for use with the MGS. To evaluate the performance of the terminals with the MGS, a series of four full-scale crash tests was conducted: two redirection tests, NCHRP Report 350 Test Designations 3–34 and 3–35, and two head-on impacts, Test Designations 3–30 and 3–31. The results from the four crash tests were found to meet all relevant safety requirements. The SKT-MGS and FLEAT-MGS end terminals are the first successfully tested end terminals for use with the MGS.

Analysis of indenting, buckling and piercing of aluminum beverage cans using both physical testing and computer simulation was performed in order to develop a better understanding of the sidewall structural strength of the cans. This understanding can be used to help design better cans and/or improve manufacturing processes.Simulation of the sidewall indentation was done with an impacting sphere. Parameters investigated included the sphere size and velocity, and the impact height along the sidewall. Buckling simulation of the dented can was then performed. Results from the deformed can buckling model compared well with physical testing based on buckled geometry, buckling load, and external work to buckle. Severe damage to a can that might occur during the manufacturing process was investigated by studying piercing of the can sidewall. Impacts of 5 and 10 m/s were performed with both blunt (flat) and sharp (45° tip) steel rods. It was found that separated elements with tied nodal constraints more accurately represent the failure behavior of the can subjected to a piercing load than merged element nodes. It was also found that the more crushing a can undergoes before piercing occurs, the more energy the can material absorbs. However, there is an upper limit to the crushing based on the speed and shape of the impactor.

A bullnose median barrier was designed and successfully crash tested head-on at 100 km/h with a 2000-kg pickup truck. After a failed pickup truck test, LS-DYNA was used to simulate the failed system, to determine the cause of the failure, and to evaluate a solution to the problem. Subsequent testing substantiated the LS-DYNA predictions. To keep up with the design project deadlines, some features of the simulation model were simplified. For other features, however, great attention to detail was required to make a useful model. Specifically, a considerable amount of effort went into defining the material failure criteria and appropriate mesh density for the guardrail, rolling tires for the truck model, and application of the relatively new cable element in LS-DYNA. The simulation effort is documented to demonstrate how LS-DYNA can be used to solve difficult design problems in roadside safety applications.

Recent findings suggest a key role for platelet activating factor in neuroinjury. For this reason we evaluated the effects of the platelet activating factor antagonist apafant (4-(2-chlorophenyl)-9-methyl-2[3(4-morpholinyl)-3-propanol-1- yl[6H-thieno[3.2-f[[1.2.4]triazolo]4,3-1]]1.4]diazepine on farct volume and local cerebral blood flow following irreversible occlusion of the left middle cerebral artery in rats to assess the direct and vascular components of apafant's action. We measured infarct volume 48 hours after middle cerebral artery occlusion. The effect of multiple doses of apafant (30 mg/kg p.o.) was tested in both pretreatment (n = 8) and posttreatment (n = 8) groups. In the pretreatment group apafant was given 30 minutes before and 2, 6, and 18 hours after occlusion. Rats of the posttreatment group received apafant 1, 6, and 18 hours after middle cerebral artery occlusion. We also examined the effect of a single dose of apafant given 30 minutes prior to occlusion (n = 9) on local cerebral blood flow determined 2 hours after middle cerebral artery occlusion. Both regimens of apafant effectively decreased infarct volume. The reduction in cortical infarct volume was 59% (p less than 0.01; H test, U test) when the rats were treated before and after vessel occlusion whereas the decrease was 47% (p less than 0.05; H test, U test) when treatment began 1 hour after occlusion. Apafant did not change local cerebral blood flow after occlusion compared with controls. We suggest that the cytoprotection afforded by apafant occurs mainly via a direct effect on brain tissue and has no major vascular component.

The effects of the calcium channel blocker nimodipine and the non-competitive NMDA-antagonists MK-801 and phencyclidine (PCP) on infarct size 48 h after occlusion of the middle cerebral artery (MCA-O) were evaluated in the rat. Nimodipine was given at a dose of 0.3 mg/kg s.c. 30 min prior and 8, 16, and 24 h after MCA-O. MK-801 (1 mg/kg i.p. or 10 mg/kg i.p.) or PCP (0.3, 1.0, 3.0, 10, or 30 mg/kg i.p.) were administered 30 min prior to ischemia. In additional experiments 30 mg/kg PCP was given 1, 3, or 5 h post ischemia. Nimodipine and 1 mg/kg MK-801 reduced cortical infarct volumes significantly by 50% and 55%, respectively, while cortical infarct size fell by 32% and total infarct volume was not altered significantly after administration of 10 mg/kg MK-801. Pretreatment with 10 or 30 mg/kg PCP reduced cortical infarction by 47–53% and total infarct volumes by 39–42%. Posttreatment with PCP was effective if started at 1 or 3 h post ischemia.

In recent years, NASCAR and the Indy Racing League have improved the safety of their racetracks through the installation of the Steel And Foam Energy Reduction barrier (SAFER). The new barrier consists of a high-strength, tubular steel skin that distributes the impact load to energy-absorbing foam cartridges in order to reduce the severity of the impact, extends the impact event, and provides the occupant of the race car additional protection. During installation of the SAFER barrier, the designers realized that certain race tracks were designed with the emergency track exit in the outside of the corner. Because the SAFER barrier needed to be installed in these corners, a gate mechanism had to be designed for the barrier that would provide access to the track while retaining the safety performance of the system. Full-scale crash testing of the first SAFER gate design showed that the gate did not posses sufficient capacity to handle the loads experienced during a worst-case impact scenario. Non-linear finite element analysis was then used to redesign the gate mechanism. The original gate design was simulated using LS-DYNA in order to validate the computational model. Modifications to increase the capacity of the gate mechanism were designed and analyzed until suitable results were obtained through simulation. Finally, the redesigned SAFER gate was successfully full-scale crash tested.Copyright © 2005 by ASME

Design for safety includes not only the vehicle and occupant protection system but also the structures that vehicles hit. One such example includes temporary concrete barriers. Often in work zones on bridges there is very little room available for barrier deflections when impacted by errant vehicles. Thus, deflections of the barriers must be severely restricted to prevent the barrier from being deflected off of the deck, followed closely by the striking vehicle. A tie-down design was generated consisting of a steel base plate with two vertical steel tubes, each with a crosshead tube blockout. Nonlinear finite element analysis of the new design focused on gauging the performance of the design as well as optimizing the structural requirements and anchor loads. Results of simulating a full-scale crash test predicted that the proposed design would be capable of safely constraining the barriers during an impact event.

The objective of this study was to determine the effect of nimodipine on infarct development and local brain pH after middle cerebral artery occlusion in the rat. Female Fischer-344 rats were subjected to permanent occlusion of the left middle cerebral artery by electrocoagulation. After 6, 12, or 24 hours, brains were frozen, and infarct size, degree of edema formation, and local brain pH were quantified by standard histology or the umbelliferone technique, respectively. In control rats, cortical infarct size was increased from 29.5 microliters at 6 hours to 72.5 microliters at 24 hours after vessel occlusion. In striatum only, an insignificant increase from 15.2 to 24.7 microliters in infarct volume was observed during this period. Edema increased from 7% to 22% in cortical and from 4% to 39% in the striatal infarct areas during this time. Nimodipine (0.1 mg/kg s.c.), given 45 minutes before and again 8 and 16 hours after middle cerebral artery occlusion, did not alter infarct size at 6 hours but considerably improved outcome at later times. Edema formation was lower at 12 hours in the group treated with the calcium antagonist (p less than 0.05). By contrast, effects on local brain pH were seen as early as 6 hours after the vessel occlusion. Nimodipine greatly reduced the areas exhibiting the lowest pH values beyond pH 6.0 (p less than 0.05). Similar effects by nimodipine on brain pH were observed in the 12-hour series, whereas at 24 hours after middle cerebral artery occlusion, a shift to more alkalotic values was noted with no overt differences between control and drug-treated groups.(ABSTRACT TRUNCATED AT 250 WORDS)

We conducted the present study to investigate the effects of 5-hydroxytryptamine agonists on brain morphology after the induction of focal cerebral ischemia by permanent occlusion of the left middle cerebral artery in rats and mice. Forty-eight hours after vessel occlusion, the damage was quantified in rats by planimetry and subsequent integration on cresyl violet-stained serial sections and in mice by planimetric analysis of the damaged cortical surface after counterstaining with carbon black. All 5-HT1A agonists investigated substantially decreased cortical infarct size in the rat focal ischemia model (p less than 0.05). Drugs were applied 30 minutes before the induction of ischemia, and efficacy was demonstrated for 8-OH-DPAT (1 mg/kg s.c.), buspirone (10 mg/kg i.p.), gepirone (10 mg/kg i.p.), ipsapirone (10 or 30 mg/kg i.p.), and Bay R 1531 (1 mg/kg i.p.). The most pronounced effects were seen with the higher dose of ipsapirone and Bay R 1531, both compounds reducing cortical infarct size by more than 60%. Except for 8-OH-DPAT, the 5-HT1A agonists also caused a reduction in total infarct volumes. In a separate series, ipsapirone (30 mg/kg i.p.), applied 1 hour after vessel occlusion, led to a reduction in cortical and total infarct volumes by about 50% compared with corresponding controls (p less than 0.05). In neither series was striatal damage influenced. We tested the compounds in the mouse ischemia model over a broad dose range.(ABSTRACT TRUNCATED AT 250 WORDS)

The present study investigates the effects of the 5-hydroxytryptamine1A agonist ipsapirone on electroencephalography and somatosensory evoked potentials after middle cerebral artery occlusion in the rat. We implanted 17 silver ball electrodes symmetrically distributed over the skull in 14 rats and registered electroencephalography activity and somatosensory evoked potentials before, 1 hour, and 1 week after permanent occlusion of the left middle cerebral artery. Before vessel occlusion, a symmetric distribution of electroencephalography power was seen over both hemispheres. Middle cerebral artery occlusion caused a complete abolishment of electroencephalography power in the frontolateral aspects of the affected hemisphere. When electroencephalographic recordings 7 days after the insult were superimposed with three-dimensional-reconstructed pictures of the infarct, a close correspondence of the extention and spatial orientation was noted. Two negative and two positive peaks were consistently recorded before middle cerebral artery occlusion. In both control and ipsapirone-treated (30 mg/kg i.p. 30 minutes after induction of ischemia) animals, the vessel occlusion caused a severe reduction in amplitudes of somatosensory evoked potentials in all areas under record (p less than 0.05). One week after middle cerebral artery occlusion, amplitudes of somatosensory potentials over the lesioned hemisphere were still significantly (p less than 0.05) lower than preischemic values in the control group. When compared with the corresponding values 1 hour after middle cerebral artery occlusion, an albeit insignificant tendency toward increased amplitudes was observed in most areas under record. By contrast, in ipsapirone-treated animals, significant differences compared with preischemic values were no longer present 1 week after the vessel occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)

The lipid peroxidation inhibitor U74006F (21-[4-(2,6-di-1-pyrrolidinyl-4-pyrimidinyl)-1-piperazinyl-16-methylp regna- 1,4,9 (11)-triene-3, 20-dione) was tested for cerebroprotective properties in the rat. Transient forebrain ischemia was induced by occlusion of the carotid arteries and simultaneous lowering of the blood pressure to 40 mmHg. Repetitive doses of 10 mg/kg U74006F were administered intraperitoneally 10 min before and again 30 min and 24 h after the transient forebrain ischemia. U74006F did not significantly improve histological outcome in this model, suggesting lipid peroxidation to be a minor determinant for the neurological outcome under these experimental conditions.

The effects of different cerebro-protective agents on selected key enzymes of the energy metabolism of rat primary glial cultures and rat cerebral cortex were studied. As indicators for the capacity of the most important pathways of energy metabolism the following enzyme activities were determined: hexokinase (HK), phosphofructokinase (PFK), pyruvate kinase (PK), lactate dehydrogenase (LDH), glucose-6-phosphate dehydrogenase (G-6-P-DH), malate dehydrogenase (MDH), glutamate dehydrogenase (GDH), and cytochrome-c-reductase (CCR). After a one week growth period, rat glial cultures were incubated for 3 or 4 weeks with the substances to be tested. Bencyclane (5 X 10(-5) mol/l) increased the activities of HK, G-6-P-DH, and LDH, whereas PFK and CCR were reduced. Pyritinol (10(-4) mol/l) led to a higher G-6-P-DH activity, simultaneously lowering the values for PFK, CCR, PK, LDH, and MDH. Under the influence of an extract of the leaves of Ginkgo bilobae (EGB; 100 mg/l) PFK, LDH, and MDH activities were reduced. All these alterations in enzyme activities went along with simultaneous reductions in protein content, therefore not allowing to exclude toxic effects with regard to the doses used. Moreover, direct interference with the analytical procedure was demonstrable for bencyclane and EGB. Piracetam (10(-3) mol/l), flunarizine (10(-6) mol/l), dihydroergocristine (5 X 10(-6) mol/l), and nicergoline (5 X 10(-6) mol/l) failed to induce any alteration in the employed doses. The most striking effects were obtained with meclofenoxate which was tested at 10(-3) and 10(-4) mol/l. The higher dose caused an elevation of HK, PFK, CCR, G-6-P-DH, GDH and MDH activities, while slightly reducing PK. With the lower dose of meclofenoxate CCR and G-6-P-DH activities were increased. Short-term incubation of the cultures with 10(-3) mol/l meclofenoxate for 24 hr led to an increase in LDH, G-6-P-DH, and GDH activities. Chronic incubation with meclofenoxate (10(-3) mol/l) followed by 48 hr deprivation of the drug resulted in elevated HK, PFK, CCR, G-6-P-DH, GDH, and MDH activities. These changes were accompanied by alterations in related metabolite levels. These include elevations in the concentration of creatine phosphate and fructose-1,6-bisphosphate, whereas glucose-6-phosphate levels were reduced. After one week of meclofenoxate deprivation the activities of CCR and G-6-P-DH were still elevated. The metabolites of meclofenoxate dimethylaminoethanol (DMAE; 10(-3) mol/l) and p-chlorophenoxyacetic acid (10(-3) mol/l) were also investigated.(ABSTRACT TRUNCATED AT 400 WORDS)

The effects of naftidrofuryl on postischemic neuronal damage and on local cerebral blood flow (LCBF) were examined in a rat model of forebrain ischemia (occlusion of carotid arteries and hypotension). Ischemia was induced for 10 min. LCBF was measured after 2 and 10 min of recirculation. A histological evaluation of cell loss in the hippocampal areas was performed 7 days after ischemia. Naftidrofuryl (10 mg/kg) was administered intraperi-toneally 15 min before ischemia. The drug reduced the percentage of necrotic neurons in the CA 1 and CA4 sector of the hippocampus, while the LCBF of these hippocampal sections was not significantly altered. Thus, naftidrofuryl is suggested to protect hippocampal neurons against ischemic damage mainly by a direct effect on brain parenchyma.

In this report the effects of phencyclidine (PCP) on physiologic variables, local cerebral blood flow (LCBF), and on hippocampal cell damage were measured in a rat model of forebrain ischemia (2-vessel occlusion and hypotension). Ischemia was induced for 10 min. LCBF was determined after 2 min of recirculation, using the [14C]iodoantipyrine technique. Hippocampal cell loss was quantified histologically 7 days postischemia as the percentage of acidic stainable neurons. Intravenous application of PCP (2 mg/kg) at 15 min prior to ischemia left postischemic LCBF unchanged, but neuronal damage was significantly reduced in hippocampal CA1 sector from 46 to 15.7%. PCP is concluded to reduce ischemic damage of neurons mainly via a direct effect on brain tissue.

By means of the [14C]-2-deoxyglucose method the local cerebral glucose utilization (LCGU) was measured in 41 brain regions in autoimmune New Zealand Black (NZB) mice and in Carworth Farm Winkelmann (CFW) mice, which served as the control strain. At the age of 6 months, the mean LCGU of all measured areas and brain stem nuclei was 67.7 mumol glucose/(100 g x min) in the nonautoimmune CFW mice. These LCGU values are within the limits published by other observers. In contrast, in the aged-matched NZB mice the glucose use was markedly reduced, the mean LCGU of all measured areas being 37.7 mumol glucose/(100 g x min). These findings suggest that the immunological, morphological and behavioural abnormalities in the aged NZB mouse correlate with a reduced functional activity of the central nervous system, measured as reduced cerebral glucose utilization.

Summary Two models of experimental cerebral ischemia in rats were developed and used. The first model was permanent occlusion of both carotids up to 3 weeks, the second model the temporal occlusion of both carotids and systemic hypotension for 10 min. Rats treated by the first experimental set were investigated after one, 2 and 3 weeks. In all groups, about 40% of so treated animals had territorial infarcts, often more than one in the animal in question. These infarcts developed from necrotic, pale areas to ischemic cysts and this copied the evolution of human territorial infarction. Astroglial reaction was only seen in the border zone. In the second model, rats preferentially developed, as known, the so called delayed ganglion cell necrosis in the field CA 1 of the hippocampus. Cells were not altered on the second, but damaged on the sixth day after experimental ischemia. In both models the hippocampus was damaged, however in the first the damages were morphologically distinct from the damage in carotid occlusion in systemic hypotension. The first experimental model suits better for human territorial infarction, the second is highly reproducible and thus provides a much better experimental tool.