Beam Guardrail Research Articles

Numerical study on the anti-collision performance of recycled foam concrete beam guardrail under vehicle collision

Recycled foam concrete (RFC) possessed excellent energy absorption capabilities and could be used in the anti-collision field. To address the insufficient anti-collision performance of existing guardrails, this paper presented a novel RFC beam guardrail by combining RFC with box-shaped steel shells. The quasi-static compressive tests and drop hammer impact tests were applied to analyze the static and dynamic mechanical characteristics of RFC with different densities and sand-cement ratios. Then, the vehicle collision performance of the RFC beam guardrail (RBG) and standard beam guardrail (SBG) was tested by LS-DYNA. The results showed that, compared with SBG, RBG had better guiding and energy absorption effects, reduced the peak vehicular acceleration by 44.15 % and the maximum guardrail displacement by 73.22 % during vehicle collisions, and mitigated the damage to the vehicle. Therefore, it is a viable way to utilize RFC to fabricate RBG, which could not only repurpose the construction and demolition wastes (CDW) but also acquire guardrails with enhanced anti-collision performance.

An experimental study on the impact resistance of a new three-wave beam steel guardrail

It is crucial to examine the impact resistance of W-beam guardrails on both sides of the highway in order to limit the severity of impact incidents and safeguard passengers. Given its importance, this article investigates the impact resistance of the new three-wave steel guardrail. To be specific, the study uses ANSYS to establish the vehicle impact barrier model in which the guardrail is embedded in concrete and soil column. The new accurate model of the three-wave beam guardrail collision stimulates the deformation degree of the guardrail under the impact of vehicles with different masses and speeds. According to the simulation analysis’ findings, the guardrail with the post embedded in the concrete had a maximum displacement of 568.48 mm, which was less than the specification’s maximum dynamic deformation of 750 mm and met the requirements for Grade 8 protection. In contrast, the guardrail with the post embedded in the soil had a maximum displacement of 679.466 mm, which was less than the specification’s maximum dynamic deformation of 750 mm.

Multi-objective optimization design of post-soil system for enhanced W-beam guardrail containment performance

In the W-beam guardrail system, the post can provide sufficient lateral force through interaction with the subgrade and can create the necessary containment function by connecting with the W-beam rail panel. The purpose of this study is to evaluate the best embedment depth and section size of two different posts in the same subgrade from the perspectives of maximum lateral force and occupant ridedown acceleration for enhanced the containment performance of guardrail protection system in China. An accurate lateral force measurement method is used for the inertia effect in collision problems. And the exact finite element model of post-soil interaction is built by combining dynamic impact test with detailed finite element study. Then the Genetic algorithm (GA) was used to determine the optimum value of spread and then the GA-RBF was applied to construct the surrogate models of the analytical objective, which increased the accuracy of fitting. Finally, the embedment depth and structure size were obtained using multi-objective genetic algorithm. Full-scale crash test results show that the optimum design results meet the requirements. Through optimization design, W-beam guardrail has been greatly improved, which improves the crash safety of corrugated beam guardrail.

Study on the Collision Simulation and Optimization of Wave Beam Guardrail on Superhighway of Grade I

Study on the Collision Simulation and Optimization of Wave Beam Guardrail on Superhighway of Grade I

An improved mathematical model for vehicle crashagainst highway guardrails

Highway guardrail is a kind of important road traffic safety facility. When a vehicle is travelling on a highway, it can lose control because of accident. The guardrail can prevent the vehicle from rushing directly out of the road, so as to reduce the injury to the driver in the vehicle. Therefore, the guiding performance, anti-collision performance and buffer performance of the guardrail are important indexes to reflect the highway guardrail safety in the traffic accidents between vehicle and guardrail. The process of collisions between vehicles and guardrails is a complex motion, affected by multiple factors such as the movement patterns and types of vehicles, the types of guardrail, the bending stiffness of the beams, the speed of collision, the angle of collision, etc. The accuracy of energy estimation when vehicle collides with guardrail is the foundation of highway guardrail design, installation and improvement. Many experts and scholars at home and abroad have done a lot of theoretical research and experimental verifications on the safety performance of highway guardrail, and analyzed the anti-collision ability and energy absorption effect of highway guardrail. Single degree of freedom model is the most widely used mathematical model of vehicle collision in highway guardrail. The traditional model is more suitable for calculating the maximum impact force of small vehicles, but it is not accurate for large vehicles. However, due to the unreasonableness of the model in the theoretical derivation process, there is a large error in the mathematical model, especially in estimating the accuracy of the energy value of the large vehicle collision guardrail. Practice shows that the current guardrail cannot withstand the impact of large vehicles. Once large vehicles collide with the corrugated beam guardrail, the guardrail will collapse in most cases, and the vehicle will rush out of the road directly, so it is very difficult to exert the protective function of the guardrail. The anti-collision performance of guardrail is poor, which is related to the existing calculation model, which results in insufficient strength in the design of guardrail.

A comparison of freeway median crash frequency, severity, and barrier strike outcomes by median barrier type

Median-crossover crashes are among the most hazardous events that can occur on freeways, often resulting in severe or fatal injuries. The primary countermeasure to reduce the occurrence of such crashes is the installation of a median barrier. When installation of a median barrier is warranted, transportation agencies are faced with the decision among various alternatives including concrete barriers, beam guardrail, or high-tension cable barriers. Each barrier type differs in terms of its deflection characteristics upon impact, the required installation and maintenance costs, and the roadway characteristics (e.g., median width) where installation would be feasible. This study involved an investigation of barrier performance through an in-depth analysis of crash frequency and severity data from freeway segments where high-tension cable, thrie-beam, and concrete median barriers were installed. A comprehensive manual review of crash reports was conducted to identify crashes in which a vehicle left the roadway and encroached into the median. This review also involved an examination of crash outcomes when a barrier strike occurred, which included vehicle containment, penetration, or re-direction onto the travel lanes. The manual review of crash reports provided critical supplementary information through narratives and diagrams not normally available through standard fields on police crash report forms. Statistical models were estimated to identify factors that affect the frequency, severity, and outcomes of median-related crashes, with particular emphases on differences between segments with varying median barrier types. Several roadway-, traffic-, and environmental-related characteristics were found to affect these metrics, with results varying across the different barrier types. The results of this study provide transportation agencies with important guidance as to the in-service performance of various types of median barrier.

Dimension Determination of Highway Guardrail Based on Safety Collision with Vehicle

The highway guardrail is the last secure defense which can protect the driver and passenger safety and make the vehicles along the original correct direction when out of control. Collision simulation between vehicle and semi-rigid waveform beam guardrail was achieved. Collision model was given and dimension optimization of the semi-rigid waveform beam guardrail was completed. Dynamic explicit finite element method was applied to simulate and analyze collision process. Optimized height of the lower beam and thickness of the upper and lower beams were obtained, which helped save material, solve the tripping phenomenon and increase safety property of the highway guardrail.

Optimization design of corrugated beam guardrail based on RBF-MQ surrogate model and collision safety consideration

As the main safety facility on the highway, a guardrail system is very essential for the highway traffics safety. In this paper, the Finite Element (FE) models of the vehicle and the corrugated beam guardrail system were created. Two types of widely used corrugated beam semi-rigid guardrails were simulated, which were the W-beam guardrail and the Thrie-beam guardrail. The collision between the corrugated beam guardrail systems and the vehicle body was analyzed. In the collision process, the snagging effect of the post to the vehicle body was also concerned. Under the considerations of the collision safety and the mechanism of the snagging effect, the multiobjective optimization problem was defined with dimensional sizes of guardrails to be the design variables. And the radial basis function (RBF) was applied to construct the regression models of the analytical objective, which increased the accuracy of fitting. The Pareto set and the optimal solution were obtained. After the optimization design, the W-beam guardrail and Thrie-beam guardrail were both greatly improved, that increased the collision safety between the corrugated beam guardrail and the vehicle body. This kind of analytical method can also be used for the crashworthiness optimization between any other cars and guardrails.

Structural and Safety Investigation of Statewide Performance of Weathered Steel Beam Guardrail in North Carolina

This paper evaluates the structural integrity and safety performance of weathered steel beam guardrail (WSBG) in North Carolina. WSBG is a popular alternative to galvanized steel guardrail (GSG) in that it is an aesthetic solution that blends in with the surrounding natural environment. A New Hampshire study, however, found that WSBG deteriorates more quickly. That study prompted an FHWA recommendation discouraging the use of WSBG across the country. This paper describes a comprehensive study of all WSBG installations in North Carolina, where weather conditions and deicing practices are generally much less severe than in New Hampshire. The research results did not show any trends of deteriorating thickness as a function of guardrail age (the oldest installation was almost 30 years old), elevation (the tallest installation was 4,200 ft), and annual average daily traffic (the highest traffic volume was 27,000 vehicles per day). The WSBG at all 25 test sites was shown to be above AASHTO minimum thickness specifications of 0.096 in. at a 95% confidence level. From a safety perspective, the research results suggested a lower percentage of injury collisions at WSBG installations relative to GSG installations at comparison sites, although low crash sample sizes made a more robust comparison difficult. Overall, this research suggests there are no structural concerns about using WSBG in North Carolina. The findings of this study may have broader policy implications for other states.

Compliance Testing of a Bullnose Median Barrier System; NCHRP Report 350

A new bullnose guardrail system for the treatment of median hazards was developed and successfully crash tested according to the safety criteria set forth in NCHRP Report 350. The new system consists of a nose section 4500 mm wide by 4824 mm long, comprising three sections of curved thrie beam guardrail attached to parallel sides of thrie beam guardrail 4500 mm apart. The nose section was designed to safely capture and contain vehicles impacting the nose. Two 6 × 25 steel cables were attached behind the top two humps of the nose section to ensure vehicle capture in the event the thrie beam ruptured. Additionally, the first five sections of guardrail had horizontal slots cut in the valleys of the rail to improve vehicle capture and reduce the formation of large kinks that could pose a threat to a vehicle as the system deformed to absorb an impact. The research study included computer simulation modeling using LS-DYNA and full-scale vehicle testing using 2000-kg pickup trucks and 820-kg small cars in accordance with the Test Level 3 safety performance requirementd specified in NCHRP Report 350. Nine full-scale crash tests were performed on the new system. Several changes were made to the bullnose system to improve its safety performance during the course of the testing and development.

DESIGN AND SIMULATION OF A SEQUENTIAL KINKING GUARDRAIL TERMINAL

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 a plastic hinge. Deformation is then localized at the plastic hinge until the hinge contacts the deflector plate and a new kink develops. Critical steps in the design process include selection of the deflector plate geometry and design of structural components required to support the system during a full-scale vehicular impact. This paper describes the use of LS-DYNA for these critical portions of the design process. Predictions of the energy dissipation for the sequential kinking impact head were only 7% below values obtained from dynamic impact tests.