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• Traffic barriers are hard protection systems that also affect driver sight along curves. • The use of higher guardrails with respect to minimum standards should be carefully evaluated. • Guardrail height impacts on lateral and longitudinal driver behaviour. • The higher the barrier, the outermost the trajectories. • Male and female drivers behave differently, with males travelling at higher speeds than females. Drivers consider traffic barriers (e.g., guardrails) a protection system, a hard obstacle and a sight obstruction. Hence, the possibility of using containment level barriers which are higher and superior than the minimum required by current standards should be carefully evaluated. Moreover, research investigations into their impact on driver behaviour should be designed so as to distinguish between the effects associated with each of the three roles cited above. This driving simulation study investigates how drivers adapt their longitudinal and transversal behaviour when negotiating curves with guardrails of different heights on horizontal-vertical coordinated two–lane rural road settings, with consideration given solely to the sight obstruction effect of the guardrails. Fifty-four participants drove four out of the eighteen possible scenarios obtained when the same horizontal alignment is combined with three vertical profiles with three inner roadside treatments (no guardrails, 0.75 m two–wave and 0.95 m three-wave guardrails) and the two driving directions. Research outcomes confirm that guardrail height has a significant impact on lateral and longitudinal behaviour. With the minimum standard, i.e., the minimum height, drivers stay closer to the roadside, while higher guardrails result in drivers increasing their lateral distance. Speeds are influenced by the interaction between the guardrail and other geometric and human factors. Male and female drivers adapt differently to the limitation in the available sight distance caused by the guardrail: males increase their speed, adopting a more aggressive behaviour than females. Important safety implications due to the higher speeds and wider trajectories have to be considered at the design stage. [ABSTRACT FROM AUTHOR]

Apart from struck-by safety incidents, fall-related injuries are a major concern in bridge maintenance work. To protect against falls from bridge decks, maintenance workers largely rely on existing bridge guardrails. However, a large number of bridge guardrails do not comply with the regulatory height requirement of 42 ± 3 in. for sufficient fall protection – although appropriate for vehicular traffic. To address this fall protection issue, a few departments of transportation (DOTs) have adopted Fall Protection Supplementary Devices (FPSDs). These devices are temporarily installed on existing bridge guardrails to sufficiently increase the barrier height while work is performed on bridge decks. However, not all FPSDs are compatible with every bridge guardrail. Therefore, to provide sufficient protection, DOT decision makers are tasked with identifying FPSDs that are compatible for each guardrail application. This generally has involved physically installing FPSDs and assessing compatibility on a trial-and-error basis. The use of such inefficient techniques have resulted in significant errors, wasted resources, productivity losses, and an increased likelihood of struck-by safety incidents. To address this issue, the objective of this study is to propose an efficient, cost-effective, and safe approach to assessing compatibility using virtual prototyping methods. In addition, to illustrate the use of the proposed method, a case example of the compatibility testing between two bridge guardrails in North Carolina and three separate FPSDs is presented. It is expected that the proposed method will provide a useful mechanism for DOTs to select suitable FPSDs to protect their workforce. [ABSTRACT FROM AUTHOR]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: Steel beam longitudinal barriers protect errant vehicles from roadside hazards; when impacted, they safely redirect the impacting vehicle and minimize the probability of serious injury. Guardrail end terminals are devices placed on the ends of longitudinal barriers and are frequently hit by vehicles that leave the roadway. Crash reconstruction is the effort to determine how a vehicle crash has occurred. Reconstruction is performed by several groups, including designers and testers of roadside safety devices so that they design and test for real-world conditions, and also by departments of transportation in order to determine appropriate warrants, maximizing the benefit–cost ratio for limited resources. This paper focuses on two items: first, the numerous types of energy-absorbing guardrail end terminals are identified and delineated and second, a crash reconstruction technique for determining the initial velocity of a vehicle impacting a guardrail end terminal based upon conservation of momentum and conservation of energy is developed. By understanding the types of guardrail terminals and being able to reconstruct real-world crashes, highway planners, designers and maintenance people will have significant more information than is currently available to aid in the goal of mitigating roadside crashes. [Copyright &y& Elsevier]

Abstract: Introduction: This study analyzes the in-service performance of roadside hardware on the entire urban State Route system in Washington State by developing multivariate statistical models of injury severity in fixed-object crashes using discrete outcome theory. The objective is to provide deeper insight into significant factors that affect crash severities involving fixed roadside objects, through improved statistical efficiency along with disaggregate and multivariate analysis. Method: The developed models are multivariate nested logit models of injury severity and they are estimated with statistical efficiency using the method of full information maximum likelihood. Results: The results show that leading ends of guardrails and bridge rails, along with large wooden poles (e.g. trees and utility poles) increase the probability of fatal injury. The face of guardrails is associated with a reduction in the probability of evident injury, and concrete barriers are shown to be associated with a higher probability of lower severities. Other variables included driver characteristics, which showed expected results, validating the model. For example, driving over the speed limit and driving under the influence of alcohol increase the probability of fatal accidents. Drivers that do not use seatbelts are associated with an increase in the probability of more severe injuries, even when an airbag is activated. Impact on industry: The presented models show the contribution of guardrail leading ends toward fatal injuries. It is therefore important to use well-designed leading ends and to upgrade badly performing leading ends on guardrails and bridges. The models also indicate the importance of protecting vehicles from crashes with rigid poles and tree stumps, as these are linked with greater severities and fatalities. [Copyright &y& Elsevier]