Road Restraint Systems Research Articles

Hybrid Road Barrier Design As Aesthetic Safety Feature and Urban Furniture

Abstract— There are various types of road barriers such as steel W beam, steel cable, concrete and wooden (timber) that have been used all over the World. They all have some advantages and disadvantages from different kinds of aspects such as construction time, ease of installation, low-cost, proven effectiveness, impact resistance, durability, service life, maintenance, etc. but to attain a more pleasant drive especially in historical and natural urban roads or scenic highways, installing wooden (timber) barriers can be considered as a more aesthetically pleasing alternative. In addition to aesthetic, wooden barriers can be preferred for their impact energy and sound absorption capabilities especially in urban roads. With the design, it is also estimated that light effect of oncoming traffic will be blocked. The main idea is to use hybrid barriers for both aesthetic safety feature in scenic or historical roads and urban furniture. This paper also summarizes comparisons among conventional road barrier systems considering the European standard EN 1317, Road Restraint Systems and provides a discussion of future designs.
 
 Index Terms—road restraint system, timber barrier, hybrid barrier, road barrier, urban furniture

Development of a continuous motorcycle protection barrier system using computer simulation and full-scale crash testing

Road restraint systems are designed to minimize the undesirable effects of roadside accidents and improve safety of road users. These systems are utilized at either side or median section of roads to contain and redirect errant vehicles. Although restraint systems are mainly designed against car, truck and bus impacts there is an increasing pressure by the motorcycle industry to incorporate motorcycle protection systems into these systems.In this paper development details of a new and versatile motorcycle barrier, CMPS, coupled with an existing vehicle barrier is presented. CMPS is intended to safely contain and redirect motorcyclists during a collision event. First, crash performance of CMPS design is evaluated by means of a three dimensional computer simulation program LS-DYNA. Then full-scale crash tests are used to verify the acceptability of CMPS design. Crash tests were performed at CSI proving ground facility using a motorcycle dummy in accordance with prEN 1317-8 specification. Full-scale crash test results show that CMPS is able to successfully contain and redirect dummy with minimal injury risk on the dummy. Damage on the barrier is also minimal proving the robustness of the CMPS design. Based on the test findings and further review by the authorities the implementation of CMPS was recommended at highway system.

The guidelines and principles for planning and design of road restraint systems

The project RID 3A Road Safety Equipment (RoSE) implemented by the Gdansk University of Technology within the RID programme, aims to conduct a comprehensive study and analyses of different vehicle containment systems (PN-EN 1317) and types of support structures (PN-EN 12767) and their performance. Within the project an analysis will be conducted of available research reports and domestic and foreign experiences looking at road restraint systems and support structures applications. The paper will present a comparison of the guidelines and principles for the design and application of road restraint systems. Similarities and differences in the approach to different solutions will also be discussed. The above analyses will form the basis for the development of tools for selecting and applying road restraint systems in Poland.

Investigating the influence on safety of retrofitting Italian motorways with barriers meeting a new EU standard

ABSTRACTObjective: A new European Union (EU) regulation for safety barriers, which is based on performance, has encouraged road agencies to perform an upgrade of old barriers, with the expectation that there will be safety benefits at the retrofitted sites. The new class of barriers was designed and installed in compliance with the 1998 (European Norm) EN 1317 standards for road restraint systems, which lays down common requirements for the testing and certification of road restraint systems in all countries of the European Committee for Standardization (CEN). Both the older and new barriers are made of steel and are installed in such a way as to avoid vehicle intrusion, but the older ones are thought to be only effective at low speeds and large angles of impact. The new standard seeks to remedy this by providing better protection at higher speeds. This article seeks to quantify the effect on the frequency of fatal and injury crashes of retrofitting motorways with barriers meeting the new standards.Methods: The estimation of the crash modification was carried out by performing an empirical Bayes before–after analysis based on data from the A18 Messina–Catania motorway in Italy. The methodology has the great advantage to account for the regression to the mean effects. Besides, to account for time trend effects and dispersion of crash data, a modified calibration methodology of safety performance was used.Results: This study, based on data collected on 76 km of motorway in the period 2000–2012, derived Crash Modification Factor point estimates that indicate reductions of 72% for run-off-road fatal and injury crashes and 38% in total fatal and injury crashes that could be expected by upgrading an old safety barrier by complying with new EU 1317 standards. The estimated benefit-cost ratio of 5.57 for total crashes indicates that the treatment is cost effective.Conclusions: The magnitude of this benefit indicates that the retrofits are cost-effective even for total crashes and should continue in any European country inasmuch as the estimated Crash Modification Factors are based on treatment sites that are reasonably representative of all European motorways.

Road Safety Barriers, the Need and Influence on Road Traffic Accidents

Constantly increasing intensity of road traffic and the allowed speed limits seem to impose stronger requirements on road infrastructure and use of road safety systems. One of the ways to improve road safety is the use of road restraint systems. Road safety barriers allow not only reducing the number of road traffic accidents, but also lowering the severity of accidents. The paper provides information on the technical requirements of road safety barriers. Various types of road safety barriers and their selection criteria for different types of road sections are discussed.The article views an example of a road traffic accident, which is also modelled by PC-Crash computer program. The given example reflects a road accident mechanism in case of a car-to-barrier collision, and provides information about the typical damage to the car and the barrier. The paper describes an impact of the road safety barrier type and its presence on the road traffic accident mechanism. Implementation and maintenance costs of different barrier types are viewed. The article presents a discussion on the necessity to use road safety barriers, as well as their optimal choice.

Observations on the relationship between European standards for safety barrier impact severity and the degree of injury sustained

Road restraint systems are roadside structures that include safety barriers, crash cushions, terminal of barriers, the transitions among different road restraint systems, motorcyclist protection devices, etc. These systems are used to protect vehicle occupants from dangerous roadside elements and are a key issue in roadside safety.In Europe, safety barriers are currently designed for different performance levels using three main criteria: containment, impact severity and deformation of the barrier.The impact severity level is exclusively associated with injury risk to vehicle occupants and assumes that different severity levels correspond to different levels of injuries.From these observations, three questions emerge: what consequences can be expected for the passengers of an errant vehicle when it is contained by a safety barrier? Systems with different impact severity levels lead to diverse severity consequences? What are the benefits of using barriers with lower impact severity levels?To answer these questions this paper examines how the number of run-off-the-road crashes and victims – associated with different safety barriers impact severity levels – changes as traffic grow.The empirical results show that the effect of safety barriers functional characteristics on road safety only depends on impact severity levels adopted if level C is considered. As a result impact severity levels A and B are similar and their discriminating thresholds need to be revised.

Using multibody-system modeling to make accurate predictions of vehicle impacts on road restraint systems

Road restraint systems have the aim to prevent vehicles from leaving the road, thus to elude obstacles (lightening posts etc), to protect the environment (water protection areas etc) or to prevent fall hazards at bridges (protecting people and housing underneath bridges). With regard to these different protective aims, the European standard EN 1317 classifies vehicle restraint systems (VRS) into different containment levels for ‘temporary’, ‘normal’ or ‘higher containment’. To classify and certify a VRS to these levels, EN 1317 requires carrying out standardized full-scale impact tests, causing substantial expenses. To reduce such costs, EN 1317-part 5 explicitly allows replacing those full-scale impact tests by computational simulations under certain limitations, in particular if a VRS is only subject to modifications. Due to the high requirements on reproducing the real impact tests by simulations, the modeling of the VRS as well as of the vehicle demands for great accuracy and high skills. Already minor changes on the model of the VRS or vehicle may cause significant changes in results. While it seems at the moment that FEM models are the preferred choice for this, the paper will show that the method of MBS provides an equally or even better simulation approach. The MBS models are assembled using macro-objects from former experience [e.g. Neuenhaus et al. 2007 [12]] offering simulations with comparably short runtime. In particular favorable for parametric studies, the use of MBS models allows the modification of system parameters directly by changing viscoelastic element parameters. To illustrate the potential and possible accuracy of using MBS, the results from real full-scale impact tests are faced with the results from simulation runs. To show the generality of the method, one of the examples represents a rather flexible (soft) VRS, and the other one represents a much more stiff construction.

Investigation of Occupant Fatalities and Injuries During the Impact of Vehicle and Road Safety Barrier

The main purpose of any road restraint system is saving human life and minimizing injuries. The efficiency of road restraint system is its capability to hold vehicle on the road, to decrease occupant injuries and damage to the impacted objects. The road restraint systems currently used in Lithuania meet the European Standard EN 1317. Acceleration Severity Index (ASI) and Theoretical Head Impact Velocity (THIV) are derivative values used in this standard mainly to describe simulation of vehicle and safety barrier impact situations and to study vehicle crash dynamics. This paper presents simulation of different situations of vehicle and road restraint system crash. Computer impact simulation analysis was performed as well as comparable investigation of conventional injury criterions Head Impact Criteria (HIC) and those used in the European Standard EN 1317.

Dual phase versus CMn strip steels: comparison of quasi-static and dynamic connection properties for road safety barriers

The use of high strength steel grades in automotive applications has been widely recorded. This is due largely to vehicle weight reduction programmes as well as increases in vehicle crash safety legislation. This represents the steel industry’s response to the challenge that vehicle components manufactured from steel could get replaced with alternative materials, such as aluminium and polymers. Consequently, new high strength steel grades have been developed to offer credible alternatives. Recently, the UK government has released a new specification, BS EN 1317-1-2-3-4: Road Restraint Systems, to which all new safety barrier designs have to comply. However, much of this development and subsequent usage has been targeted at automotive manufacturers. Road safety barrier technology has not evolved in the same way when compared to vehicle technology. Therefore, a study has been undertaken to assess the outcome of using some of these novel high strength steel grades for the manufacture of road safety barrier components. Quasi-static and dynamic tensile testing at different velocities was undertaken. Representative connection coupons were used to understand the energy absorbing properties of a dual phase steel grade when compared to the current CMn steel grade. The present study presents some initial results as to the increased performance that could be gained from utilising new high strength steel grades for the production of road safety barrier systems.

The Researches of Effectiveness of Road Restraint Systems

The Researches of Effectiveness of Road Restraint SystemsThe work describes model and experimental tests on the road restraint systems with particular attention to vehicle collisions with a concrete protective barrier. Vehicle and protective barrier crash tests include the experiment results in three basic fields: intensity of influence of the collision effects on vehicle passengers, collision impact on a vehicle and the road restraint system. It presents a test track concept as well as criteria for performing and evaluating the crash tests with a passenger vehicle and a safety barrier. The experimental tests were performed according to the test methodology recommended by the standard [2]. Examples of model test results were compared with experimental test results obtained on the test track.

Safety barrier performance predicted by multi-body dynamics simulation

This paper presents results obtained from analyses using the multi-body dynamics program MEPHISTO. Particular aspects of the applied method are described. The comparison of numerically predicted and corresponding full-scale test results of several impact tests carried out in cooperation with industry partners indicates the reliability of this tool. Impact severity and containment capacity are predicted with acceptable accuracy for various flexible or rigid road restraint systems. Hence, the collected data allow for the drawing of a correlation between severity indices such as ASI and THIV. This knowledge could be a help to solve the quite contentious discussion concerning the addition of an impact severity-level class C and the introduction of more reliable limits for the occupant injury severity, particularly against the background of the recently issued open letter “The Safety Barrier Scandal” by the road safety equipment industry and the European Road Federation.

Compatibility between passenger vehicles and road barriers during oblique collisions

In the European and US testing procedures for road barriers, vehicles are specified for the tests essentially by their mass properties. However, vehicles with similar mass can behave quite differently during a crash event. For the specific crash situation with the roadside restraint systems, e.g. W-beam guardrail, cable barriers, etc., the vehicle structure has to be compatible with the road restraint systems in geometry and crash stiffness to ensure safe operation during the interactions of vehicles and road barriers. The goal of this paper is to make a parametric investigation for the geometric compatibility between the compact passenger vehicles and the road barriers. The Finite Element model Ford Festiva and a weak-post W-beam guardrail were used for analyzing the oblique impact situation with a high impact speed and a small angle. For this specific situation the dynamic responses of the vehicle and the guardrail during impacts were investigated to study their structural interactions. The simulation results of the modified vehicle model and guardrail model were reasonable in comparison with the crash test data under the similar impact conditions.

Selection of Roadside Safety Barrier Containment Level According to European Union Standards

The new European Standards EN 1317-1/2 define the performance classes of road restraint systems and induce a growing interest for roadside safety. However, analytical procedures, like benefit-cost analysis, are not used in Europe for the selection of specific roadside safety features at specific locations or for the development of warrants, policies, and guidelines on a systemwide basis. A model for the selection of roadside safety barrier performance level according to European Union standards is presented. The new procedure is an encroachment-based benefit-cost analysis that takes into account the effective performance level of road safety barriers on the basis of a comparison between the real-world impact conditions and the impact conditions of the full-scale crash tests performed according to the European Committee for Standardization standards. The behavior of the safety barriers in relation to the impact conditions has been studied by performing nonlinear dynamic finite element analysis of collisions of heavy-goods vehicles against steel road safety barriers. As a result of the study, analytical relationships between a barrier’s containment capacity and impact conditions have been obtained. The expressions obtained allow one to evaluate the number of vehicles successfully redirected from the safety barriers in relation to the type of road, to the geometrical features of the road, to the traffic volume and composition, and to the safety barrier containment level. The model allows one to calculate the benefits arising from the greater number of vehicles redirected from safety barriers with greater level of performance and to compare roadside alternatives.