Steel Guardrail Research Articles

Geometrical optimization and evaluation of the bridge safety guardrail

Abstract Lately, the rapid growth of traffic led to the construction of a new freeway bridge to ease the road congestion. This paper studied the crash behaviour of steel guardrails for semi-heavy traffic roads used on bridges. The guardrail structure is tested according to the SR EN 1317 standards at two velocity cases, corresponding to the TB 11 and TB 51 impact test description. To perform this evaluation study, the guardrail structure is first modelled in CAD environment software, respecting the commercial dimensions. The boundary conditions, the material properties assignment, and the load case creation are done by using dedicated FEA software. The obtained results are analysed and are proposed some design improvements to the base guardrail structure. The improved guardrail structure is tested under the same work conditions as the base structure. The conclusions of this research are presented in the last part of the paper.

Lifetime cost analysis of concrete barriers and steel guardrails

This study investigates the lifetime costs associated with concrete barriers and steel guardrails. We introduce a cost analysis methodology that incorporates critical factors such as construction costs, maintenance costs, exposure risks during maintenance activities, and the costs imposed to traveling public through the increased traffic and the crash outcomes. We integrate various parameters including economic factors, road geometry, general weather condition, and traffic mix to estimate a location-dependent cost for each type of barrier accurately. A software tool, named CalBarrier, was developed during this study to carry out the calculations and the comparison of lifetime cost of aforementioned barriers. An inherent strength of this research is its reliance on recent real data extracted from various databases of California Department of Transportation (Caltrans), ensuring precision and relevance in accounting for various influential factors. Drawing insights from Caltrans practices and interviews with their personnel, this study emphasizes the intricate decision-making process involved in mitigating safety risks and reducing operational expenses. Although our data originates from California, the methodology for life cycle cost analysis, and our software are applicable for regions with different socio-economic conditions by deploying user input costs, making our findings a valuable resource for other areas facing comparable challenges.

Collision Study on New Aluminum Alloy W-Beam Guardrail

Highway guardrails are safety installations set along the sides or center of roads to prevent vehicles from veering off the roadway, thereby protecting pedestrians and vehicles. However, traditional W-beam guardrails have issues such as poor energy absorption, susceptibility to rust, short lifespan, and a high risk of vehicles running off the road during severe collisions. Therefore, this study employs the partial differential equations of the vertical motion of beams to investigate the relationship between the deformation of wave beams and their moment of inertia. The cross-sectional shape of traditional W-beam guardrails was optimized accordingly. Combining this with the high ductility of aluminum alloy Al 6061-T6, a new aluminum alloy W-beam guardrail was proposed. Finite element simulation models of traditional steel guardrails, new steel guardrails, and the new aluminum alloy guardrail were established to evaluate the performance of the three types of guardrails. The results show that the deformation of the wave beam is inversely proportional to the square root of its moment of inertia. Compared to traditional W-beam guardrails, the moment of inertia of the new guardrail’s cross-section increased by 28.6%. In finite element collision simulations, the new guardrail reduced deformation by 12.8%, lowered the risk of vehicles running off the road, and improved safety performance.

Test and application of movable steel barrier with grade SB light composite corrugated beam

In this study, movable steel barrier with grade SB light composite corrugated beam is designed, which addresses the problems of the prior central partition belt portable guardrail in terms of easy mobility, local safety, easy construction, and other indications. This guardrail employs explicit algorithms to conduct a dynamic finite element simulation analysis and a real vehicle crash test, and verifies the guardrails' blocking, guiding, and buffering functions in accordance with the SB level collision conditions listed in the Standard for Safety Performance Evaluation of Highway Barriers (JTG B05-01-2013). According to the results, the safety performance of SB grade lightweight composite corrugated beam movable steel guardrail meets the requirements of the Standard for Safety Performance Evaluation of Highway Barriers (JTG B05-01-2013). In addition, the guardrail can be opened for 12 meters in 1 minute and returned to close in 2 minutes. The opening and restoration of the movable guardrail is superior to the previous central divider movable guardrail. This guardrail has been tried for some high-speed and its safety performance has been verified again in actual high-speed vehicle collisions.

Experimental investigation of the response of guardrail posts embedded in road shoulder material under quasi-static and dynamic impact loading

The main functions of vehicle restraint systems (VRS) are to redirect errant vehicles and prevent them from entering an opposing lane or carriageway, as well as preventing them from colliding with structures along the road [1]. In the case of steel guardrail systems, fulfilment of these requirements greatly depends on the soil-post interaction, which influences the deformation and energy dissipations of the VRS during impact.To date, there is no unified method of modelling the behaviour of guardrail posts embedded in road shoulder material in crash tests simulations. For this reason, the influence of soil type and state as well as post characteristics on the observed motion of vehicle and VRS cannot be adequately evaluated, which is, however, necessary to improve and optimise a VRS without increasing the number of crash tests.This paper presents the findings of a series of static and dynamic full-scale loading tests conducted with different road shoulder materials and post types, the aim being to create an experimental database for modelling the soil-post interaction in crash test simulations. The novel dynamic and static testing techniques used ensures repeatability and enables the reliable evaluation and interpretation of the results.We found that not only the static and dynamic post response but also the failure mode are significantly influenced by the relative soil density and post embedment length. As long as there is no yielding of the post section, the dynamic post resistance varies with increasing impact energy until a maximum value, which depends on the dynamic horizontal bearing capacity of the post. Any further increase in impact energy has no influence on the post resistance.

Head-on and angular impact-based investigation of mechanical behavior of guardrail post types with finite element analysis

The geometric sections of guardrail systems that provide roadside safety are important in terms of their safety and structural performance. Guardrail systems generally consist of posts and beam. One of the critical components that affect the performance of steel guardrail systems is the post. Many different types of posts are used in practice. In this sense, the mechanical performance of the most commonly used S-C-I-Z-rectangular-circular post types in this study was investigated and compared on the basis of their failure performances. For this, the finite element (FE) model of the pendulum system, which was previously validated with empirical data, was used. In the FE analysis, the mechanical performance of posts embedded in soil and fixed on top of the ground was investigated by the pendulum system in head-on and angular impact situations. As a result of the FE analyses; the mechanical performances were different for head-on and angular impact situations. However, since circular and rectangular posts show the best performance in case of angular impact, and considering in terms of guardrail systems, angular impact situations are a matter of concern, it has been understood that the use of closed-section posts as circular and rectangular in guardrail systems will provide safety and economic advantages.

Finite Element Analysis and Investigation of Critical Impact Point of Steel Guardrails Affecting Safety and Structural Performance

After the guardrails are designed, the structural adequacy and safety criteria are determined by the relevant standards and full-scale crash tests. One of the widely used standards is European Norm 1317 (EN1317). Guardrail systems generally consist of rails and posts. The guardrails are more rigid around the posts, which are mounted on the ground or embedded in soil at certain intervals. Therefore, it is important for driver/passenger and roadside safety to determine the most critical point in terms of structural and safety performance and design according to the most unfavourable situation. With this motivation, in this study, the effect of different impact points on the structural and safety performance of the H1W4 guardrail was investigated by finite element (FE) analysis. For this purpose, first of all, the finite element models of the H1W4-A system were calibrated and validated with real crash test data. Then, with the help of the validated models, analyses were completed for different impact points as 0.5, 1.0, 1.5 and 2.0 meters with a half-meter difference for the standard 2-meter post spacing. In the light of the measured safety parameters such as Acceleration Severity Index (ASI), Theoretical Head Impact Velocity (THIV) and structural performance criteria such as working width (W) and exit angle (α), the critical impact point for the guardrail was determined. Contrary to what is generally known, crashing vehicles into flexible points (0.5 and 1.0 m) rather than impacting rigid points (1.5 and 2.0 m) creates a more negative situation in crash tests.

Simulation research on the collision between freight cars and expressway three-wave beam steel guardrail

Simulation research on the collision between freight cars and expressway three-wave beam steel guardrail

Crashworthiness analysis of a composite guardrail under impact loading

Road safety barriers prevent cars from deviating from the roads. Guardrails as common roadside safety barriers protect cars from dangers alongside the roads, such as steep slopes and trees, and redirect traffic from road hazards. Conventional guardrails are generally made of metal or concrete. Although steel guardrails absorb a high amount of crash energy by deformation, these types of guardrails have short lifecycles of less than 15 years. Due to their unique properties, composite materials are potential candidates to use as guardrails. The present study considers the three types of guardrails (steel, composite, and fiber metal laminate (FML)), and the crash model is developed according to standards. LS-DYNA software is employed to simulate and conduct the crash test In the first stage, impact simulation is performed on a carbon/epoxy composite plate. In the next step, impact simulation is performed on a metal fiber multilayer (FML) plate with carbon fiber and aluminum metal. Then, the crash test on the steel guardrail is completely simulated. These three stages are performed to verify the proposed model. In the next stage, the crash test for a carbon/epoxy composite guardrail is simulated, and the effect of different parameters is investigated. Finally, a crash test on the FML guardrail with carbon fibers and steel metal is simulated. Two FML samples with [CE/Steel/CE] layups are considered. The absorbed energy, specific energy, and acceleration severity index (ASI) for all different guardrails are obtained and compared to determine the optimum guardrail regarding energy absorption, mass, and ASI parameters. Results reveal that sample FML-B guardrail is the best of the three guardrail types, with the highest specific energy absorption and lower ASI parameter.

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.

Solid safety barriers as a highway traffic noise reduction strategy

Placing solid safety barriers (concrete crash barriers) along a highway, instead of steel guard rail, can help reduce traffic generated noise at nearby sensitive sites. The effectiveness of these barriers on traffic noise levels is dependent on the height of the barrier, the number of traffic lanes, vehicle mix, and the elevation of the receiver relative to the barrier. The effect of solid safety barriers for sites at a variety of distances from a highway has been investigated for both city streets and freeways of various widths using the U.S. Federal Highway Administration Traffic Noise Model (TNM). TNM predicted noise level reductions, attributable to solid safety barriers, were developed for research scenarios in locations with both hard soil and lawn ground types. Results show a readily perceptible and sometimes substantial noise reduction at sites within a few hundred feet of the roadway.

Experimental and numerical comparative crashworthiness analysis of innovative renewable hybrid barrier with conventional roadside barriers

Guardrails are passive safety elements used in roadside safety. They are commonly manufactured as steel and concrete. There are also guardrail systems in which wood and steel materials are used together. This study investigated the crashworthiness performance of a newly developed F-shape type renewable hybrid barrier (RHB) system consisting of wood, steel and sand components. Commonly used steel guardrail and F-shape type concrete barrier were used for performance comparison. For this, a pendulum impactor has been set up. The impact performances of the aforementioned guardrails in the pendulum assembly were determined, then tests were carried out by modelling the pendulum system in the LS-DYNA environment for full-size crash testing and calibration. Calibration and validation were performed by comparing the Finite Element (FE) results with the pendulum results. Then, to determine the crashworthiness and safety of RHBs and compare them with steel and concrete barriers, full-size finite element models were created in the TB11 test standard specified in the European roadside safety standard - EN1317. As a result of the analysis, while providing the comfort of a concrete barrier after impact, RHBs perform close to the steel barrier in terms of safety. This study will be the first step before the prospective full-scale crash analysis.

Experimental Analysis of Guardrail Structures for Occupational Safety in Construction

Background: Guardrails are structures that protect workers from falling from heights at construction sites. Objective: The objective is to evaluate experimental models by applying static and impact loads to wood and steel guardrails. Methods: Brazilian and international standards were consulted to define the actions applied to guardrails, which were tested experimentally in three models of each material in a full-size prototype. Results: The experimental results indicate that the models studied could support the applied loads, and no local or global system rupture occurred. However, the displacements for the static load of 1500 N/m required by Brazilian RTP 01 for both models did not comply with Brazilian standard NBR 14718 because they had displacements above 20 mm, despite meeting other international standards for static testing and impact testing. Conclusion: From the results obtained in the experimental tests, it was possible to verify that the structures withstood the applied loads and could be used safely in civil construction works. However, the load requirements of RTP 01 are excessive, and NBR 14718 is not suitable for checking temporary guardrail structures. This demonstrates the need for the Brazilian standard to be revised to guide the dimensioning and verification of structures in order to adapt to international standards.

Motion Planning for Vibration Reduction of a Railway Bridge Maintenance Robot with a Redundant Manipulator

Motivated by the potential applications of maintenance and inspection tasks for railway bridges, we have developed a biped climbing robot. The biped climbing robot can climb on the steel guardrail of the railway bridge with two electromagnetic feet and implement the maintenance and inspection tasks by a redundant manipulator with 7 degrees of freedom. To reduce the vibration of the manipulator caused by the low rigidity of the guardrail and the discontinuous trajectories of joints, a motion planning algorithm for vibration reduction is proposed in this paper. A geometric path accounting for obstacle avoidance and the manipulator’s center of gravity is determined by the gradient projection method with a singularity-robust inverse. Then, a piecewise quintic polynomial S shape curve with a smooth jerk (derivative of joint angular acceleration) profile is used to interpolate the sequence of joint angular position knots that are transformed from the via-points in the obstacle-avoidance path. The parameters of the quintic polynomial S-curve are determined by a nonlinear programming problem in which the objective function is to minimize the maximus of the torque exerted by the manipulator on the guardrail throughout the jerk-continuous trajectory. Finally, a series of simulation experiments are conducted to validate the effectiveness of the proposed algorithm. The simulation results show that the tracking errors of the trajectory with the proposed optimization algorithm are significantly smaller than the tracking errors of the trajectory without optimization. The absolute values of mean deviation of the tracking errors of the three coordinate axes decreased by at least 48.3% compared to the trajectory without vibration-reduction in the triangle working path and linear working path trajectory following simulations. The analysis results prove that the proposed algorithm can effectively reduce the vibration of the end effector of the manipulator.

Study on the anti-collision performance of basalt fiber reinforced polymer beam–column guardrail

In view of poor performance and short service life of conventional bridge guardrails against vehicle collision in practice, a continuous basalt fiber reinforced polymer (BFRP) guardrail was proposed. The quasi-static bending test of BFRP pipe was carried out and simulated by nonlinear explicit dynamics software LS-DYNA, and then the new guardrail was evaluated using LS-DYNA. Results revealed that the vehicles do not appear to cross, ride across, and pass through the guardrails, implying that the BFRP guardrail has a good guiding performance. The vertical and horizontal acceleration values at the seat position during the collision are all less than 200 m/s2 in the specification, indicating that the BFRP guardrail has a good cushioning function for the vehicle. Compared with the steel guardrails, the BFRP guardrail can better reduce the acceleration of the vehicle, and the energy absorption of the BFRP guardrail is higher than that of the steel guardrail. Therefore, the anti-collision performance of the BFRP guardrail is better than that of the steel guardrail.

Intra- and inter-site variability of soil contamination in road shoulders – Implications for maintenance operations

This study addresses soil contamination in vegetated road shoulders with diffuse inflow of runoff. It aims (i) to characterize the spatial distribution of three metals (copper, lead, zinc) and PAHs, and (ii) to identify influencing factors for the inter-site differences. An extensive sampling campaign was carried out on forty road segments in the Paris region, targeting various distances and soil depths. Copper and zinc contamination was found to be mainly restricted to the first 30 cm from the road, where their concentrations ranged respectively between 40 and 270 mg.kg−1, and between 150 and 950 mg.kg−1 (with a few additional extreme values related to the presence of a galvanized steel guardrail). Lead contamination was moderate (< 100 mg.kg−1 in more than 75% of the sites) and relatively uniform across the width of the shoulders. Conversely, highest PAH concentrations were found further from the road. These differences between contaminants were likely due to the varying importance of wet weather-related processes and atmospheric transport in their dispersion mechanisms. Copper and zinc concentrations correlated well with the traffic density, which alone explained ≥ 69% of the inter-site variability, whereas lead and PAHs did not exhibit such dependence. Soil organic matter was found to control the “ceiling” concentration of metals, thus limiting the maximum amounts that can be intercepted from road runoff. These results illustrate the feasibility of estimating contamination levels on road shoulders, and thus offer interesting perspectives for better consideration of the infrastructures' maintenance needs and improved routine operations.

Evaluating sustainable product alternatives by combining life cycle assessment with full-cost accounting: A highway guardrail case study

Full-cost accounting techniques incorporate the environmental and societal burdens a product generates through its manufacture, use, and disposal into that product’s price. This research generates full-cost prices for functionally equivalent chromated copper arsenate (CCA) treated wood and galvanized steel guardrail posts by combining previously conducted life cycle inventory analyses results with secondary emission valuation data. Based on the analysis, both CCA-treated posts and galvanized steel posts have environmental damage costs associated with emissions generated through the product’s manufacturing, use, and disposal stages. After developing full-cost prices for product alternatives, CCA-treated wood guardrail posts were found to be a more economical and environmentally responsible alternative to galvanized steel. In addition to generating full-cost prices, this research uses Monte Carlo simulation to provide estimates of variability around CCA-treated wood and galvanized steel damage costs.

In Situ Strength Testing of Temporary Steel Guardrails Installed on Existing Flat-Roof Parapets

AbstractThe installation of guardrails around a roof perimeter is an efficient way to protect construction workers against falls from heights, provided the guardrails are strong enough to arrest a ...

Assessing vehicle restraint systems on horizontal curves

Horizontal curves, an element of road infrastructure, have a statistically high number of accidents. Considering that horizontal curves in the last ten years have had app. 10% of all road accidents representing app. 14% of all fatalities on Polish roads, the issue is serious and requires more research and proper road safety treatments. Data for 2007 - 2016 show that in the case of accidents on horizontal curves app. 45% of the fatalities happened as a result of crashing into roadside obstacles such as signs and first of all trees. This shows that horizontal curves require road safety equipment, and specifically, safety barriers. Key to this is using the right equipment and the right parameters. To achieve that, full-scale crash tests should be conducted to be followed by numerical tests. The article will present a synthesis of the available research conducted in Poland and abroad. An assessment will be made of four crash tests of TB32 with barriers that have a steel and cable guardrail. They are the outcome of the RID 3A “Road safety equipment” project called RoSE. Building on these tests, numerical test results will be presented.

Influence of geometric parameters on the restraint of guardrail posts by asphalt mow strips

Asphalt pavement mow strips, used as a vegetation barrier in guardrail systems, have typically been regarded as a rigid layer in roadside design. However, geometric parameters of the mow strip such as thickness and rear distance behind the post have a significant impact on the amount of restraint the asphalt layer provides to resist translation and rotation by the posts. In this paper, a standard steel guardrail post designed with a range of asphalt mow strip dimensions is evaluated. A survey of the use of asphalt pavement mow strips in the United States was undertaken to determine an initial set of mow strip designs for investigation. Static tests were performed based on these designs, and finite element models were calibrated using the test data and parallel material characterization experiments. Utilizing the calibrated finite element model, simulations were performed on a wide variety of asphalt mow strip designs. Simulation and experimental results were correlated to develop a set of quantitative performance criteria. These criteria were used to assess the amount of ground-level restraint on a guardrail post caused by a given asphalt mow strip design in comparison with the existing design recommended by American Association of State Highway and Transportation Officials.