Road Safety Barriers Research Articles

Automobile response to road safety barriers upon collision

During a collision between an automobile and a road safety barrier, the vehicle will go through many behavior transition phases. This research will focus on determining the behavior of two car models including a sedan car and a pickup truck in collision with two safety road barriers using numerical simulation. This paper will also present images, total force graphs, and velocity graphs throughout the process to evaluate the vehicle's behavior at different impact speeds and angles. It is recognized that at similar impact speeds, collision angles, and barrier types, the pickup truck suffers more damage than the sedan. In addition, the pickup truck colliding with a concrete barrier exhibits the highest force, while the sedan colliding with a W-Beam barrier records the lowest force among the four collision types. Regarding the road safety barrier, the concrete barrier has a shorter force increase/decrease duration than the W-Beam barrier.

Impact properties of an end of life tires’ rubber. Numerical validation considering large strain and strain rate conditions

The objective of the authors is to demonstrate that the inclusion of renewed rubber from recycled end of life tires (ELT) can improve the performance of any structural system designed to dissipate impact energy. An interesting application would be its use in road safety barriers. This research starts with the rigorous characterization of the recycled material in order to include it in a viable numerical model. The authors presented, in a previous work (*), the experimental viscoelastic properties of recycled rubber, obtained under impact conditions. Bergström–Boyce (BB) nonlinear viscoelastic model was selected as the most suitable to fit the material behavior. This model is defined by nine material constants that are impossible to obtain, uniquely and directly, considering that only compression test results are available as input data. To overcome this challenge, optimization methods were applied resulting in as many sets of parameters as used optimization methods were considered and, moreover, remarkable differences between constants were observed. Solving this problem is the motivation of the present research: the validation of the optimization method by mean of the numerical evaluation of the obtained sets. The software considered for the numerical evaluation of impact tests (LS-DYNA®) had two slightly different implementations for the BB model: the original, based on the work published in 2009 by Dal & Kaliske and a more recent one implemented by Bergström, based on his works published in 1998 and 2000. This leads to a new question: which is the most appropriate implementation-optimization method for calibrating this material? This paper provides the answer to this question carrying out a complete comparative numerical analysis of all sets by means of explicit dynamics simulations. All calibrations, using the original LS-DYNA® implementation, were in perfect agreement with the experimental results. However, only one optimization method produced acceptable results for the most recent approach. A robust method to characterize recycled rubber from recycled tires using the Bergström–Boyce nonlinear viscoelastic model is presented, despite the experimental limitations (González-Vega et al. 2022).

Improving Traffic Safety in Existing and New Road Tunnels with the Novel NDBA Concrete Safety Barrier

Abstract Two main elements are essential in terms of road traffic safety. The first element is accident prevention and the second is the minimization of accident severity once a crash has occurred. Concrete safety barriers have very good anti-collision performance against roadside obstacles, relatively modest construction and maintenance costs, and low dynamic deflection and therefore are widely used in tunnels. Thanks to their characteristic redirective profile these barriers can redirect errant vehicles into their original lane after collisions. However insufficient research has been done for increasing the performance of concrete barriers purposely designed for tunnel installations. This research presents the new “NDBA Tunnel” concrete safety barrier designed and constructed by the Italian Road Operator ANAS indicated to be installed in road tunnel sections for safety improvements. In Europe, road safety barriers must be designed in compliance with the European Standard EN 1317. Therefore, the barrier “NDBA Tunnel” was subject to the TB11 and TB81 full-scale crash tests according to the European EN 1317 regulation. The results prove the barrier's ability to absorb impact loads of light and heavy vehicles with a working width W2. Therefore, the NDBA concrete barrier can be installed on existing or new tunnels at a distance less than or equal to 70 cm from the facing of the tunnel wall.

SUITABILITY ANALYSIS OF PEDESTRIAN WAYS WITH THE ACTIVE LIVING STREET CONCEPT APPROACH

Kampung Pelajar is an educational area that causes travel attractions on the surrounding roads so there is a tendency to experience traffic density during daytime and night. Today the implementation of the government zoning system in education has encouraged equal access to educational services through a student admission system that considers the distance from home to the school. The implementation of this system has an impact on reducing loading on roads that have indications of high density due to student movement during rush hour. Based on initial observations, walking on pedestrian paths tend to be less when compared to vehicle. This phenomenon causes a decrease in the number of pedestrians because the function of the pathway is not optimal. This research aims to evaluate the pedestrian way suitability with the Active Living Street concept, by Mapping analysis with comparative description. The research results showed that based on the examination of four existing segmented routes, the majority of pedestrian way elements are not meet the criteria, such as obstacle, type of pavement, route dimension, signage and road marking, seatings, bollard, and safety barrier.

Indexing the Maintenance Priority of Road Safety Barriers in Urban and Peri-Urban Contexts: Application of a Ranking Methodology in Bologna, Italy

The need for clear and updated information is pivotal when authorities plan and perform routinary, periodic and emergency maintenance of both road network and their roadside assets, e.g., curbs, signals, and barriers. With particular regard to road barriers, the development of remote sensing technologies, such as Laser Imaging Detection and Ranging (LiDAR), has played a disruptive role in acquiring information, so the surveys today are predominantly automatic, faster, and less biased than the traditional (i.e., visual and manual) inventorying methodologies. However, even though they are accurate, these emerging procedures usually focus only on the surveyed elements and do not provide any other information about the surrounding environment or about the qualitative degradation of the elements. The primary objective of this research effort was to present a ranking methodology for enhancing road safety in urban contexts. Due to an innovative synthetic index which takes into account both the deterioration and the location of the surveyed elements, maintenance priority of road barriers was outlined in Bologna, Italy. All the collected information was georeferenced in a Geographic Information System (GIS) environment and hence plotted in thematic maps for an easier analysis. In addition, compliance to the norm was verified. The research was tested to provide public authorities with an effective tool in the evaluation of maintenance activities and road safety policies.

Speed estimation of a car at impact with a W-beam guardrail using numerical simulations and machine learning

This paper aimed at developing a new method of estimating the impact speed of a passenger car at the moment of a crash into a W-beam road safety barrier. The determination of such a speed based on the accident outcomes is demanding, because often there is no access to full accident data. However, accurate determination of the impact speed is one of the key elements in the reconstruction of road accidents. A machine learning algorithm was used to create the speed estimation model. The model was based on regression trees algorithms, with base regressors forming a final voting ensemble. The model was trained, validated, and tested using a database containing results from full-scale crash tests and numerical simulations. The developed machine learning model had a mean absolute error of 6.76 km/h with a standard deviation of 1.01 km/h on the cross-validation set, and a coefficient of determination, R2, of 0.85. This model was used to estimate the impact speed of the vehicle in three real road accidents with the W-beam barrier, and then the determined speeds were used in additional simulations to verify the results. A good quantitative and qualitative agreement between the simulation and accident outcomes was achieved, and this confirmed that the proposed method and the developed ML models combined with numerical simulations and full-scale crash tests can be effective tools for estimating the speed of the vehicle at impact with a roadside barrier.

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.

Road safety measures in urban scenario - A case study in bengaluru

Road safety audit is defined as a formal safety performance examination of an existing or future road or intersection by an independent, multidisciplinary team. It qualitatively estimates and reports on potential road safety issues and identifies various measures for improving safety for all road users. The current scenario of urban road accidents in our country show that urban safety is in a critical state, emphasizing the need for a current urban road safety audit. This article examines the various factors that influence safety on urban road accidents, including human, vehicle, road, external environment, and other factors, and summarizes the implications and steps taken for an urban road traffic safety audit. This article explores the current state of road safety in Bengaluru, examining the various factors that contribute to accidents and identifying potential solutions to improve safety in the city's roads. Through an analysis of existing research and data, this article aims to provide a comprehensive overview of the challenges and opportunities for improving road safety in Bengaluru, with the goal of reducing the number of accidents and saving lives. The selected area is from Uttarahalli Circle to Srinivaspura Road in Kengeri, a 7-kilometer stretch on Dr Vishnuvardhan Road, as it is a busy road connecting industrial, commercial, and educational areas and has mixed and heterogeneous traffic, leading to accidents. The audit has been conducted using the following guidelines of IRC SP: 88. Measures of road signs, markings, message signs, delineators, hazard markers, and traffic safety barriers have been done based on the requirements. In conclusion, significant measures need to be taken to improve roads safety and have them listed accordingly.

Influence of Road Safety Barriers on the Severity of Motorcyclist Injuries in Horizontal Curves

Motorcyclist safety remains a significant problem, and the overall safety of motorcyclists has been improved at a much slower rate in the last decade compared to passenger and commercial vehicles. Because motorcyclists are not protected by the vehicle frame, fatalities or severe injuries are often related to hitting a roadside object or safety barrier. The main objective of this study is to investigate relations between the presence and type of road safety barriers and the consequences of motorcycle crashes on rural roads. For this purpose, we analysed Croatian rural road-crash data from 2015–2019, tested several factors as single predictors, and combined them using binary logistic regression. The results show that run-off-road crashes and nighttime driving are significant risk factors. There was no significant positive impact of the presence of safety barriers on the crash consequences due to the unsuitability of the barriers for motorcyclists, which proves the fact that the functionality of existing safety barriers should be upgraded. The results of this study could be further used by researchers, road designers, and experts to improve road infrastructure safety on rural roads.

Influence of a Lighting Column in the Working Width of a W-Beam Barrier on TB51 Crash Test.

Road equipment, such as, e.g., road safety barriers and lighting columns, are subject to certification according to the EN1317 standard to be allowed for use on European roads. In engineering practice, due to the terrain conditions, there are cases where other road equipment is installed within the working width of road safety barriers. Such situations are not considered during the certification process. Hence, the aim of this study is to analyze the effect of a lighting column installed within the working width of the barrier on the results of the TB51 crash test. The full-scale crash test and numerical simulation of this event were conducted. In the full-scale crash test, as well as in the simulation, the lighting column prevented the barrier’s post from properly disconnecting from the guardrail, which resulted in the barrier failing to restrain and redirect the 13-t bus. The simulation was quantitatively compared to the experiment, where the correlation coefficient of ASI curves equaled 84%. The THIV curves differed significantly between the experiment and the simulation, which is explained within the paper. Next, simulations with and without the lighting column were compared. The ASI and THIV in the simulation without the column were 0.33 and 16.1 km/h, respectively. In the simulation with the column, the ASI and THIV were 0.44 and 17.7 km/h, respectively. The maximum roll angle of the vehicle in the simulation without the column was 2.01° and with the column was 5.96°. The main difference, however, was that the system without the lighting column within the working width of the barrier was capable of properly restraining and redirecting the vehicle. The specific mechanics underlying this behavior are described within the paper.

Stability of Extruded Concrete for Road Safety Barriers and Effect of Mineral Admixtures on Concrete Behaviour

Concrete barriers are distinguished by an extrudable character that facilitates their implementation using slipform machines. The first objective of this study was to formulate an extruded concrete in order to achieve stable road safety barriers with a flat-face. The tests were first carried out at the laboratory; then the most promising ones were tested on site. It was noted that the measure of the slump alone does not ensure the stability of concrete barriers on site. A range of variation of a yield stress (t0) was determined for which the concrete was extrudable and stable. This reduced the number of tests on site and therefore minimised economic costs. The second objective was to utilise local mineral admixtures with the aim of improving concrete properties and reducing environmental impacts and costs. Furthermore, the hardened concrete properties were tested for compressive strength, durability and shrinkage. The results indicated that the mineral admixtures improved the concrete compressive strength and lead to good durability while minimising shrinkage. This increased road user safety by providing high quality and reliable barriers. In conclusion, it is possible to successfully formulate an extrudable concrete in the laboratory from rheological parameters. The inclusion of mineral admixture has proven to be very beneficial.

Life cycle energy and carbon analysis of a road-safety barrier produced using recycled tire rubber

Increasing end-of-life material recovery and its application in new products is essential to reduce resource consumption. This paper assesses the cradle-to-gate life cycle energy and carbon dioxide (CO2) emissions of a new road safety barrier product to be installed around guardrails’ poles. To analyze​ the potential life cycle benefit of incorporating recycled materials, a base case product A, produced with conventional virgin synthetic rubber and polypropylene (PP), was compared with two equivalent alternatives under study: B (using recycled end-of-life tire rubber granulate (TRG) and PP), and C (using TRG and recycled polypropylene). The results show that the incorporation of recycled TRG has a positive effect in primary energy and carbon emissions. Product B presents less 38% CO2 emissions and 47% non-renewable primary energy than product A. The combination of TRG and recycled polypropylene (C), presents even more benefits: less 69% CO2 and 86% non-renewable primary energy than A. Supply chain processes and material production have much higher impacts than the product manufacturing (e.g. product molding only represents 5% of the primary energy of product A). To conclude, recycled materials incorporation should be strongly encouraged since it has a great potential to reduce current carbon emissions and primary energy of products.

ROAD SAFETY BARRIERS AND THE SAFETY OF ROAD USERS – THE ANALYSIS OF THE SITUATION IN POLAND

Road safety barriers are a basic element of the road infrastructure aimed at improving the safety of road users. Design parameters and indications for assembly are strictly regulated by the GDDKiA (General Directorate for National Roads and Motorways) guidelines in accordance with the European standards. In Poland, the most commonly used barriers are thin-walled metal sheet barriers, rope barriers, and concrete ones. The types differ in terms of technical parameters and level of security they provide. One of the purposes of installing road safety barriers is to protect road users from hitting an obstacle in the vicinity of the road, and to protect people around the accident from the effects of an uncontrolled vehicle leaving the road. The effects of a collision caused by hitting a protective road barrier depend mainly on the type of the barrier and the vehicle. The authors made a detailed and interdisciplinary analysis of data on accidents resulting from hitting a road safety barrier, comparing them with information available in the literature, combining the technical aspects of the use of barriers with a medical description of the description of typical injuries.

Biomechanics of Lumbar Spine Injury in Road Barrier Collision–Finite Element Study

Literature and field data from CIREN database have shown that lumbar spine injuries occur during car crashes. There are multiple hypotheses regarding how they occur; however, there is no biomechanical explanation for these injuries during collisions with road safety barriers (RSBs). Therefore, the objective of this study was to investigate the mechanics of vertebral fractures during car collisions with concrete RSBs. The finite element method was used for the numerical simulations. The global model of the car collision with the concrete RSB was created. The lumbar spine kinematics were extracted from the global simulation and then applied as boundary conditions to the detailed lumbar spine model. The results showed that during the collision, the occupant was elevated, and then dropped during the vehicle landing. This resulted in axial compression forces 2.6 kN with flexion bending moments 34.7 and 37.8 Nm in the L2 and L3 vertebrae. It was shown that the bending moment is the result of the longitudinal force on the eccentricity. The lumbar spine index for the L1–L5 section was 2.80, thus indicating a lumbar spine fracture. The minimum principal strain criterion of 7.4% and damage variable indicated L2 and L3 vertebrae and the inferior part of L1, as those potentially prone to fracture. This study found that lumbar spine fractures could occur as a consequence of vehicle landing during a collision with a concrete RSB mostly affecting the L1–L3 lumbar spine section. The fracture was caused by a combination of axial forces and flexion bending moments.

Modern methods of the digital virtual analysis for design and tests of road vehicle restraint systems

Widespread introduction of information technologies of virtual digital testing to reproduce vehicle impacts against vehicle restraint systems with simulation impact modeling road safety barriers, crash cushions, terminals, removable barrier sections, transitions and passive safety devices, is one of the main actions providing decline in mortality on roads as a result of the road accidents. On this basis the so-called “Virtual Digital Proving Ground” (Virtual Test House) for testing of road arrangement elements is developed. The researches, conducted for its development are based on use of modern world-class software products and numerical methods of mechanics. Digital modeling of crash-situations with arrival of vehicles on elements of road arrangement, allows to solve complex problems of the analysis of new designs now, to investigate behavior of vehicles at with arrival on the design. Implementation of intellectual systems of automated management of vehicles does not give the chance to hope for the exception of refusals, both the equipment, and control systems, that does the problem of development of the innovation passive safety systems extremely relevant. Research and development carried out MADI by the general research team together with LLC M&PQ allowed to take the major step in advance of works on increase in safety on roads, to create tools for design of new innovations, to develop reasonable standards in the field of the road systems of passive safety. In article prospects the development of these researches in scientific and practical directions and for the purpose of increase in competences of educational programs are considered.

On analysis of double-impact test of 1500-kg vehicle into w-beam guardrail system

Every day on roads many scenarios of accidents may occur. One of the measures to minimize their consequences is road safety barriers. Finite Element analyses are being increasingly used to support the physical testing of these devices. The paper addresses the issue of a secondary impact into the previously damaged w-beam guardrail system. This situation belongs to one of the most dangerous which can happen on roads and may cause serious hazards, especially if the vehicle goes through the barrier. To evaluate the crashworthiness of the road barrier, the computational model of the crash test was developed and validated against the full-scale crash test. Then two simulations of TB32 crash tests were conducted on both damaged and undamaged road barriers to assess the influence of damage on the effectiveness of the safety system during vehicular impact. The study has revealed that the partially damaged system preserved some of its original functionality.

Performance Evaluation of Vehicle Restraint Systems in the Context of Design and Installation

Vehicle Restraint Systems (VRS), a necessary component of the road design, are widely implemented by transport authorities to protect vehicles from severe incidents, mainly colliding to the roadside as well as median obstacles and other potential hazards. The performance evaluation of vehicle restraint systems at the design and installation stages is largely made according to either European or American standards. The local traffic conditions and vehicle compositions in countries, which are noticeably different from Europe and North America, necessitate a customized guideline in which the design and installation of road safety barriers are more adapted to the local conditions of the country. This paper briefly reviews the main features of EN1317, and NCHRP 350/MASH standards, which are predominantly used for the design, installation, and performance evaluation of VRS in Europe and the United States respectively. Moreover, the contribution of these standards in developing the VRS guideline for the State of Qatar is explained. The study recommends customizations to the design and installation of VRS, which are presently implemented according to the guideline developed by the Public Work Authority in Qatar. The present guideline follows European as well as American standards. The recommendations are made based on empirical studies and evidence observed by undertaking a series of site visits, audits, and perform inspections of VRS components installed on Qatari roads and highways. The study findings demonstrate the performance of VRS can be enhanced by incorporating the design and selection of road safety components such as guardrails, terminals, transitions, and crash cushions at the preliminary design stage of roads and highways. This study brings about practical insights and implications for road designers, contractors, supervision teams, and road safety auditors. Doi: 10.28991/cej-2021-03091665 Full Text: PDF

The innovative “NDBA” concrete safety barrier able to withstand two subsequent TB81 crash tests

The new NDBA concrete road safety barrier is characterized by an innovative anchorage system based on two “C” steel profiles incorporated into the terminal sections of each module and a vertical HEM 100 steel profile inserted for linking the barrier modules. Every single barrier module is fixed in the body of the road embankment and pavement layers by six IPE 80 steel beams (three for each side with a mutual distance of 2 m), each 78 cm long. The IPE 80 steel beams are placed into niches, in the lower part of the barrier.The new barrier has been analysed first by numerical simulations (LS-DYNA software) and afterwards by full-scale crash tests. One TB11 (light vehicle) and two successive TB 81 (heavy vehicle) full-scale crash tests have been performed on NDBA barrier of 72 m length. The second TB81 test was performed on a damaged barrier previously subjected to impact without it being repaired. The experiments were conducted at “CSI test centre” in Bollate, Milan (Italy).According to the EN 1317 regulation, the results have shown a containment level CL = 725 kj (H4b class), a measured maximum ASI = 1.26 (class B), a working width W = 0.74 m (class W2). The research proves that the NDBA barrier is able to withstand two subsequent heavy vehicle (38 t) impacts.In addition, the study demonstrates that the new barrier may guarantee more safety for light vehicle occupants (TB11 test) than a conventional steel safety barrier with equal containment level (H4b class).Therefore, in the near future, NDBA barrier may be installed on existing roads, especially where reduced working width (W2) is required or in motorways with high AADT values and heavy vehicle percentage.

Modeling, simulation, and validation of a TB41 crash test of the H2/W5/B concrete vehicle restraint system

The paper addresses numerical simulations of a concrete vehicle restraint system. The model is described in detail. The advanced material law of the continuous surface cap model was used to analyze the damage locations in concrete barrier segments. The results were validated against the TB41 full-scale crash test. The test was conducted in compliance with European standard EN 1317, and the validation was performed in accordance with the PD CEN/TR 16303 technical report. The force and moment envelopes of the road safety barrier during a vehicle crash are provided. The detailed concrete segment model successfully reproduced the characteristic splitting failure cracks that were found near the connection of the adjacent barrier segments in the actual structure after the full-scale crash test.

Numerical Analysis of TB32 Crash Tests for 4-cable Guardrail Barrier System Installed on the Horizontal Convex Curves of Road

Abstract Horizontal curves are one of the elements of road infrastructure where statistically a relatively high number of accidents have been reported. In the last 10 years in Poland, approximately 10% of all road accidents happened on horizontal curves of roads and was responsible for approximately 14% of all fatalities on Polish roads. Thus, this issue is important and requires extensive research and proper road safety treatments. One possible measure that may contribute to improvement of safety on road curves may be barriers. The purpose of this work is to assess, with use of numerical simulations, the performance of the 4-cable barrier systems installed on horizontal road convex curves. The most important parameters for road safety barriers are presented including the effect of various impact velocities and the radiuses of the road curves.