Brief descriptions are provided of a new cost-effectiveness analysis pro- gram, known as the Road... more Brief descriptions are provided of a new cost-effectiveness analysis pro- gram, known as the Roadside Safety Analysis Program (RSAP), which was developed under NCHRP Project 22-9. RSAP is an improvement over existing cost-effectiveness ...
Page 1. An energy-absorbing guardrail terminal was developed at the Midwest Roadside Safety Facil... more Page 1. An energy-absorbing guardrail terminal was developed at the Midwest Roadside Safety Facility in 1994 that met the safety criteria set forth in NCHRP Report 230. This terminal, known as the beam-eating steel ter-minal ...
A new tangent energy-absorbing W-beam guardrail terminal that meets National Cooperative Highway ... more A new tangent energy-absorbing W-beam guardrail terminal that meets National Cooperative Highway Research Program (NCHRP) Report 350 criteria has been developed. The terminal, designated the SKT-350, dissipates the energy of an encroaching vehicle by producing a series of plastic hinges in the W-beam as the terminal head is pushed down the guardrail. This energy-absorption concept allows for significantly lower dynamic forces on the encroaching vehicle, reducing the vehicle damage, the weight of the terminal head, the propensity for vehicle yaw and roll after impact, and the chances of buckling in the W-beam section. The energy required to move the head down the rail in this design is optimized for current criteria, but by modifying the bending geometry in the head, the average force to displace the head down the rail can be adjusted from values ranging from 11 to 60 kN (2,500 to 13,500 lb), meaning that the system can be easily modified to meet any future changes in safety performance standards. In addition to these important safety advantages, the terminal incorporates a unique cable anchor bracket that closely resembles a breakaway cable terminal anchor and a novel foundation tube design that facilitates the removal of broken posts during repair. Combining the features of reduced forces and head weight, a simple cable box and more economical soil tubes allows the system to offer the advantages of both reduced cost and improved performance.
The process of using non-linear, large deformation finite element analysis to design a new guardr... more The process of using non-linear, large deformation finite element analysis to design a new guardrail terminal system is summarized. The simulation program LS-DYNA was used to develop a sequential kinking process for energy dissipation. The sequential kinking process involves using a deflector plate to force a steel beam guardrail element to be bent around a rigid beam until it forms
Over the years, numerous work-zone, portable sign support systems have been successfully crash te... more Over the years, numerous work-zone, portable sign support systems have been successfully crash tested according to the Test Level 3 safety performance guidelines provided in the National Cooperative Highway Research Program Report 350 and accepted for use along our nation's highways. For this study, several crashworthy sign support systems were analyzed to predict their safety performance according to the new evaluation criteria provided in the Manual for Assessing Safety Hardware (MASH). More specifically, this analysis was conducted to determine which hardware parameters negatively affect a system's safety performance. To verify the accuracy of the analysis, eight systems, four with the 2270P pickup truck and four with the 1100C small car, were evaluated according to the MASH criteria. Five out of the eight tested systems failed the MASH criteria, and the other three systems performed in an acceptable manner. As a result of the analysis and verification, several hardware parameters were deemed critical for contributing to system failure under MASH and included sign panel material, top mast height, presence of flags, sign-locking mechanism type, base layout, and system orientation. Flowcharts were developed to assist manufacturers with the design of new sign support systems.
Two tie-down temporary barriers systems were developed and crash tested according to the safety p... more Two tie-down temporary barriers systems were developed and crash tested according to the safety performance criteria provided in the National Cooperative Highway Research Program (NCHRP) Report No. 350, Recommended Procedures for the Safety Performance Evaluation of Highway Features. Both tie-down systems were designed to reduce barrier displacements as well as to retain deflected barriers on the bridge deck edge.
The potential to increase suggested flare rates for strong post, W-beam guardrail systems and thu... more The potential to increase suggested flare rates for strong post, W-beam guardrail systems and thus reduce guardrail installation lengths is investigated. This reduction in length would result in decreased guardrail construction and maintenance costs, and reduce impact frequency. If the W-beam guardrail can withstand the higher impact angles, with only modest increases in accident severity, total accident costs can be reduced. Computer simulation and five full-scale crash tests were completed to evaluate increased flare rates up to, and including, 5:1. Computer simulations indicated that conventional G4(1S) guardrail modified to incorporate a routed wood block could not successfully meet NCHRP Report 350 crash test criteria when installed at any steeper flare rates than the 15:1 recommended in the Roadside Design Guide. However, computer modeling and full-scale crash testing showed that the Midwest Guardrail System (MGS) could meet NCHRP Report 350 impact criteria when installed at a 5:1 flare rate. Impact severities during testing were found to be greater than intended, yet the MGS passed all NCHRP 350 requirements. Hence, flaring the MGS guardrail as much as 5:1 will still provide acceptable safety performance for the full range of passenger vehicles. Increasing guardrail flare rates will reduce the overall number of guardrail crashes without significantly increasing risks of injury or fatality during the remaining crashes. Therefore, it is recommended that, whenever roadside topography permits, flare rates should be increased to as high as 5:1 when using the MGS.
Report 350 criteria (4). Tests were performed with three-quarter-ton pickups on both steel-and wo... more Report 350 criteria (4). Tests were performed with three-quarter-ton pickups on both steel-and wood-post W-beam guardrails. During both of these tests, the impacting vehicles deformed the guardrail significantly, experienced significant wheel snagging on the posts, and attained a high roll angle as the vehicle exited the barrier. During the wood-post guardrail test, the vehicle almost rolled over and then returned to an upright position. However, during the steel-post test, the vehicle had a slightly higher roll angle when it returned to the ground, and as a result it rolled onto its side rather than returning to its wheels. The results of these two tests were classified as marginally successful for the wood-post system and a marginal failure for the steel-post system. However, due to the high levels of variability inherent in full-scale crash-testing, it is difficult to use these test results to conclude that the wood-post guardrail performs any better than the steel-post system.
Over the years, numerous work-zone, portable sign support systems have been successfully crash te... more Over the years, numerous work-zone, portable sign support systems have been successfully crash tested according to the Test Level 3 safety performance guidelines provided in the National Cooperative Highway Research Program Report 350 and accepted for use along our nation's highways. For this study, several crashworthy sign support systems were analyzed to predict their safety performance according to the new evaluation criteria provided in the Manual for Assessing Safety Hardware (MASH). More specifically, this analysis was conducted to determine which hardware parameters negatively affect a system's safety performance. To verify the accuracy of the analysis, eight systems, four with the 2270P pickup truck and four with the 1100C small car, were evaluated according to the MASH criteria. Five out of the eight tested systems failed the MASH criteria, and the other three systems performed in an acceptable manner. As a result of the analysis and verification, several hardware parameters were deemed critical for contributing to system failure under MASH and included sign panel material, top mast height, presence of flags, sign-locking mechanism type, base layout, and system orientation. Flowcharts were developed to assist manufacturers with the design of new sign support systems.
A new tangent energy-absorbing W-beam guardrail terminal that meets National Cooperative Highway ... more A new tangent energy-absorbing W-beam guardrail terminal that meets National Cooperative Highway Research Program (NCHRP) Report 350 criteria has been developed. The terminal, designated the SKT-350, dissipates the energy of an encroaching vehicle by producing a series of plastic hinges in the W-beam as the terminal head is pushed down the guardrail. This energy-absorption concept allows for significantly lower dynamic forces on the encroaching vehicle, reducing the vehicle damage, the weight of the terminal head, the propensity for vehicle yaw and roll after impact, and the chances of buckling in the W-beam section. The energy required to move the head down the rail in this design is optimized for current criteria, but by modifying the bending geometry in the head, the average force to displace the head down the rail can be adjusted from values ranging from 11 to 60 kN (2,500 to 13,500 lb), meaning that the system can be easily modified to meet any future changes in safety performance standards. In addition to these important safety advantages, the terminal incorporates a unique cable anchor bracket that closely resembles a breakaway cable terminal anchor and a novel foundation tube design that facilitates the removal of broken posts during repair. Combining the features of reduced forces and head weight, a simple cable box and more economical soil tubes allows the system to offer the advantages of both reduced cost and improved performance.
Brief descriptions are provided of a new cost-effectiveness analysis pro- gram, known as the Road... more Brief descriptions are provided of a new cost-effectiveness analysis pro- gram, known as the Roadside Safety Analysis Program (RSAP), which was developed under NCHRP Project 22-9. RSAP is an improvement over existing cost-effectiveness ...
Page 1. An energy-absorbing guardrail terminal was developed at the Midwest Roadside Safety Facil... more Page 1. An energy-absorbing guardrail terminal was developed at the Midwest Roadside Safety Facility in 1994 that met the safety criteria set forth in NCHRP Report 230. This terminal, known as the beam-eating steel ter-minal ...
A new tangent energy-absorbing W-beam guardrail terminal that meets National Cooperative Highway ... more A new tangent energy-absorbing W-beam guardrail terminal that meets National Cooperative Highway Research Program (NCHRP) Report 350 criteria has been developed. The terminal, designated the SKT-350, dissipates the energy of an encroaching vehicle by producing a series of plastic hinges in the W-beam as the terminal head is pushed down the guardrail. This energy-absorption concept allows for significantly lower dynamic forces on the encroaching vehicle, reducing the vehicle damage, the weight of the terminal head, the propensity for vehicle yaw and roll after impact, and the chances of buckling in the W-beam section. The energy required to move the head down the rail in this design is optimized for current criteria, but by modifying the bending geometry in the head, the average force to displace the head down the rail can be adjusted from values ranging from 11 to 60 kN (2,500 to 13,500 lb), meaning that the system can be easily modified to meet any future changes in safety performance standards. In addition to these important safety advantages, the terminal incorporates a unique cable anchor bracket that closely resembles a breakaway cable terminal anchor and a novel foundation tube design that facilitates the removal of broken posts during repair. Combining the features of reduced forces and head weight, a simple cable box and more economical soil tubes allows the system to offer the advantages of both reduced cost and improved performance.
The process of using non-linear, large deformation finite element analysis to design a new guardr... more The process of using non-linear, large deformation finite element analysis to design a new guardrail terminal system is summarized. The simulation program LS-DYNA was used to develop a sequential kinking process for energy dissipation. The sequential kinking process involves using a deflector plate to force a steel beam guardrail element to be bent around a rigid beam until it forms
Over the years, numerous work-zone, portable sign support systems have been successfully crash te... more Over the years, numerous work-zone, portable sign support systems have been successfully crash tested according to the Test Level 3 safety performance guidelines provided in the National Cooperative Highway Research Program Report 350 and accepted for use along our nation's highways. For this study, several crashworthy sign support systems were analyzed to predict their safety performance according to the new evaluation criteria provided in the Manual for Assessing Safety Hardware (MASH). More specifically, this analysis was conducted to determine which hardware parameters negatively affect a system's safety performance. To verify the accuracy of the analysis, eight systems, four with the 2270P pickup truck and four with the 1100C small car, were evaluated according to the MASH criteria. Five out of the eight tested systems failed the MASH criteria, and the other three systems performed in an acceptable manner. As a result of the analysis and verification, several hardware parameters were deemed critical for contributing to system failure under MASH and included sign panel material, top mast height, presence of flags, sign-locking mechanism type, base layout, and system orientation. Flowcharts were developed to assist manufacturers with the design of new sign support systems.
Two tie-down temporary barriers systems were developed and crash tested according to the safety p... more Two tie-down temporary barriers systems were developed and crash tested according to the safety performance criteria provided in the National Cooperative Highway Research Program (NCHRP) Report No. 350, Recommended Procedures for the Safety Performance Evaluation of Highway Features. Both tie-down systems were designed to reduce barrier displacements as well as to retain deflected barriers on the bridge deck edge.
The potential to increase suggested flare rates for strong post, W-beam guardrail systems and thu... more The potential to increase suggested flare rates for strong post, W-beam guardrail systems and thus reduce guardrail installation lengths is investigated. This reduction in length would result in decreased guardrail construction and maintenance costs, and reduce impact frequency. If the W-beam guardrail can withstand the higher impact angles, with only modest increases in accident severity, total accident costs can be reduced. Computer simulation and five full-scale crash tests were completed to evaluate increased flare rates up to, and including, 5:1. Computer simulations indicated that conventional G4(1S) guardrail modified to incorporate a routed wood block could not successfully meet NCHRP Report 350 crash test criteria when installed at any steeper flare rates than the 15:1 recommended in the Roadside Design Guide. However, computer modeling and full-scale crash testing showed that the Midwest Guardrail System (MGS) could meet NCHRP Report 350 impact criteria when installed at a 5:1 flare rate. Impact severities during testing were found to be greater than intended, yet the MGS passed all NCHRP 350 requirements. Hence, flaring the MGS guardrail as much as 5:1 will still provide acceptable safety performance for the full range of passenger vehicles. Increasing guardrail flare rates will reduce the overall number of guardrail crashes without significantly increasing risks of injury or fatality during the remaining crashes. Therefore, it is recommended that, whenever roadside topography permits, flare rates should be increased to as high as 5:1 when using the MGS.
Report 350 criteria (4). Tests were performed with three-quarter-ton pickups on both steel-and wo... more Report 350 criteria (4). Tests were performed with three-quarter-ton pickups on both steel-and wood-post W-beam guardrails. During both of these tests, the impacting vehicles deformed the guardrail significantly, experienced significant wheel snagging on the posts, and attained a high roll angle as the vehicle exited the barrier. During the wood-post guardrail test, the vehicle almost rolled over and then returned to an upright position. However, during the steel-post test, the vehicle had a slightly higher roll angle when it returned to the ground, and as a result it rolled onto its side rather than returning to its wheels. The results of these two tests were classified as marginally successful for the wood-post system and a marginal failure for the steel-post system. However, due to the high levels of variability inherent in full-scale crash-testing, it is difficult to use these test results to conclude that the wood-post guardrail performs any better than the steel-post system.
Over the years, numerous work-zone, portable sign support systems have been successfully crash te... more Over the years, numerous work-zone, portable sign support systems have been successfully crash tested according to the Test Level 3 safety performance guidelines provided in the National Cooperative Highway Research Program Report 350 and accepted for use along our nation's highways. For this study, several crashworthy sign support systems were analyzed to predict their safety performance according to the new evaluation criteria provided in the Manual for Assessing Safety Hardware (MASH). More specifically, this analysis was conducted to determine which hardware parameters negatively affect a system's safety performance. To verify the accuracy of the analysis, eight systems, four with the 2270P pickup truck and four with the 1100C small car, were evaluated according to the MASH criteria. Five out of the eight tested systems failed the MASH criteria, and the other three systems performed in an acceptable manner. As a result of the analysis and verification, several hardware parameters were deemed critical for contributing to system failure under MASH and included sign panel material, top mast height, presence of flags, sign-locking mechanism type, base layout, and system orientation. Flowcharts were developed to assist manufacturers with the design of new sign support systems.
A new tangent energy-absorbing W-beam guardrail terminal that meets National Cooperative Highway ... more A new tangent energy-absorbing W-beam guardrail terminal that meets National Cooperative Highway Research Program (NCHRP) Report 350 criteria has been developed. The terminal, designated the SKT-350, dissipates the energy of an encroaching vehicle by producing a series of plastic hinges in the W-beam as the terminal head is pushed down the guardrail. This energy-absorption concept allows for significantly lower dynamic forces on the encroaching vehicle, reducing the vehicle damage, the weight of the terminal head, the propensity for vehicle yaw and roll after impact, and the chances of buckling in the W-beam section. The energy required to move the head down the rail in this design is optimized for current criteria, but by modifying the bending geometry in the head, the average force to displace the head down the rail can be adjusted from values ranging from 11 to 60 kN (2,500 to 13,500 lb), meaning that the system can be easily modified to meet any future changes in safety performance standards. In addition to these important safety advantages, the terminal incorporates a unique cable anchor bracket that closely resembles a breakaway cable terminal anchor and a novel foundation tube design that facilitates the removal of broken posts during repair. Combining the features of reduced forces and head weight, a simple cable box and more economical soil tubes allows the system to offer the advantages of both reduced cost and improved performance.
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