Performance of Breakaway Cable and Modified Eccentric Loader Terminals in Iowa and North Carolina: In-Service Evaluation

Author(s):  
Malcolm H. Ray ◽  
Jeffery A. Hopp

Developing safe and effective guardrail terminals has been a high priority for roadside safety researchers for several decades. Numerous full-scale crash tests have been performed, and many new types of terminals have been developed. Results are presented of an in-service performance evaluation of two popular guardrail terminals—the breakaway cable terminal and the modified eccentric loader terminal. The data were collected in parts of Iowa and North Carolina during a 24-month period from 1997 to 1999. The collision characteristics, occupant injuries, and barrier damage were evaluated to determine collision performance.

Author(s):  
Malcolm H. Ray

Developing safe and effective guardrail terminals has been a high priority of roadside safety researchers for several decades. Numerous full-scale crash tests have been performed, and many types of new terminals have been developed. In recent years, the FHWA has formalized the evaluation and certification process for roadside safety hardware, meaning that all guardrail terminals used on the National Highway System must satisfy the full-scale crash test and evaluation requirements of NCHRP Report 350. Although the newer guardrail terminals undoubtedly have better full-scale crash test performance, the relevancy to reducing serious and fatal injuries in real-world guardrail terminal collisions is not quite as clear. The in-service performance of guardrail terminals was evaluated to determine if upgrading the terminals to NCHRP Report 350 standards would reduce serious and fatal injury accidents.


2012 ◽  
Vol 490-495 ◽  
pp. 2676-2680
Author(s):  
Hong Jun Cui ◽  
Xiao Jing Shen ◽  
Yu Liu ◽  
Xi Xin Sun

Pave overlay to the freeway repeatedly causes the guardrail’s height lower and lower, which seriously influences its performance in protection and safety. The paper aims to work out a height-adjustable W-beam guardrail which is economic, feasible and safe to solve the shortage in barrier’s height causes from paving overlays by computer simulation tests and full-scale crash tests, which will improve the roadside safety of the guardrail and save the reconstruction cost.


Author(s):  
Ronald K. Faller ◽  
Ketil Soyland ◽  
Dean L. Sicking

An approach guardrail transition for use with the single-slope concrete median barrier was developed and crash tested. The transition was constructed with 3.43-mm-thick (10-gauge) thrie-beam rail and was supported by nine W6 × 9 steel posts. Post spacings consisted of one at 292 mm (11.5 in.), five at 476 mm (1 ft 6.75 in.), and three at 952 mm (3 ft 1.5 in.). A structural tube spacer block (TS 7 × 4 × 3/16) was also developed for use with the thrie-beam rail. Two full-scale vehicle crash tests were performed, and the system was shown to meet the Test Level 3 requirements specified in NCHRP Report 350: Recommended Procedures for the Safety Performance Evaluation of Highway Features.


Author(s):  
Brian G. Pfeifer ◽  
Dean L. Sicking

A crashworthy terminal for strong-post W-beam guardrail systems was developed at the Midwest Roadside Safety Facility at the University of Nebraska—Lincoln. The terminal incorporates an impact head that is placed over the end of a tangent section of W-beam rail. The impact head is designed to be pushed down the rail and to dissipate impact energy by cutting the W-beam along the peaks and valley to produce four essentially flat strips of steel. These flat strips are then deflected out of the path of the vehicle, striking the end of the rail. Static and dynamic component tests as well as full-scale developmental crash tests conducted during the development of this system are described. Finally, the results of the three full-scale compliance crash tests are presented and discussed. The metal-cutting guardrail terminal was shown to meet NCHRP Report 230 safety performance standards.


Safety ◽  
2018 ◽  
Vol 4 (4) ◽  
pp. 48
Author(s):  
Murat Büyük ◽  
Ali Atahan ◽  
Kenan Kurucuoğlu

Crash cushions are designed to gradually absorb the kinetic energy of an impacting vehicle and bring it to a controlled stop within an acceptable distance while maintaining a limited amount of deceleration on the occupants. These cushions are used to protect errant vehicles from hitting rigid objects, such as poles and barriers located at exit locations on roads. Impact performance evaluation of crash cushions are attained according to an EN 1317-3 standard based on various speed limits and impact angles. Crash cushions can be designed to absorb the energy of an impacting vehicle by using different material deformation mechanisms, such as metal plasticity supported by airbag folding or damping. In this study, a new crash cushion system, called the ulukur crash cushion (UCC), is developed by using linear, low-density polyethylene (LLDPE) containers supported by embedded plastic energy-absorbing tubes as dampers. Steel cables are used to provide anchorage to the design. The crashworthiness of the system was evaluated both numerically and experimentally. The finite element model of the design was developed and solved using LS-DYNA (971, LSTC, Livermore, CA, USA), in which the impact performance was evaluated considering the EN 1317 standard. Following the simulations, full-scale crash tests were performed to determine the performance of the design in containing and redirecting the impacting vehicle. Both the simulations and crash tests showed acceptable agreement. Further crash tests are planned to fully evaluate the crashworthiness of the new crash cushion system.


Author(s):  
Robert W. Bielenberg ◽  
Dean L. Sicking ◽  
John R. Rohde ◽  
John D. Reid

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.


Author(s):  
M. Mongiardini ◽  
J. D. Reid

Numerical simulations allow engineers in roadside safety to investigate the safety of retrofit designs minimizing or, in some cases, avoiding the high costs related to the execution of full-scale experimental tests. This paper describes the numerical investigation made to assess the performance of a roadside safety barrier when relocated behind the break point of a 3H:1V slope, found on a Mechanically Stabilized Earth (MSE) system. A safe barrier relocation in the slope would allow reducing the installation width of the MSE system by an equivalent amount, thus decreasing the overall construction costs. The dynamics of a pick-up truck impacting the relocated barrier and the system deformation were simulated in detail using the explicit non-linear dynamic finite element code LS-DYNA. The model was initially calibrated and subsequently validated against results from a previous full-scale crash test with the barrier placed at the slope break point. After a sensitivity analysis regarding the role of suspension failure and tire deflation on the vehicle stability, the system performance was assessed when it was relocated into the slope. Two different configurations were considered, differing for the height of the rail respect to the road surface and the corresponding post embedment into the soil. Conclusions and recommendations were drawn based on the results obtained from the numerical analysis.


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