Roadside Barriers Research Articles

Noise from various types of heavy trucks and the influence from low-height solid safety barriers

Types of heavy trucks and their characteristics vary greatly, yet noise from these vehicles is often represented by a single heavy truck category for the purpose of predicting highway traffic noise. This paper presents a case study examining heavy truck pass-by events and their associated measured maximum broadband and 1/3-octave band noise levels, sorting the trucks by various attributes to determine if there are meaningful differentiations. The study further examines the measured heavy truck noise in the presence of a roadside solid safety barrier, installed to shield motorists from natural or man-made obstacles, and can also provide some noise reduction to nearby communities. Results with and without the shielding from solid safety barriers are presented.

Investigating the Viability of Rubber Crumbs from Waste Tyres as Partial Replacement for Coarse Aggregates in Concrete

The number of waste tyres is on the increase, because of the growing use of transport vehicles. Almost one trillion waste tyres are generated in the world annually. Established methods of disposal, recycling and re-use of waste tyres have failed to keep pace with generation, proven to be ineffective, cost-intensive and in some cases environmentally unsustainable. This study aims to investigate the effects of utilizing crumbs from discarded rubber as a partial replacement for coarse aggregates in concrete. Rubber crumbs of 10 – 20mm nominal size were produced manually from waste tyres. The rubber crumbs were used to replace 10%, 20% and 30% of coarse aggregates in design concrete of 20N/mm2 target compressive strength. The effects of this material on the slump, water absorption and compressive strength of concrete were examined. The inclusion of rubber crumbs resulted in a decline in the slump of concrete up to 10% relative to the control specimen. Water absorption increased marginally at 10% replacement compared to the control specimen and recorded a maximum value of 0.77% with 30% replacement after 28 days of curing. The compressive strength of the concrete was negatively affected by the rubber crumbs. The maximum value of 13.9N/mm2 was attained at 10% replacement after 28 days of curing. Rubberized concrete with 10% replacement of coarse aggregates can be used for non-structural concrete members such as roof slabs, non–load–bearing partition walls, and roadside barriers. Chemical treatment of rubber crumbs to improve surface adhesion properties should be encouraged.

A cross-sectional study of the prevalence of medical conditions as contributors to road crashes in South Australia

Objectives With the population of Australians aged 85 or older expected to double by 2042 and the association of increased age with the greater likelihood of having medical conditions, the potential for an increase in the number crashes caused by medical conditions is of concern. This study aims to understand the prevalence of medical conditions contributing to road crashes and the characteristics of these crashes, in order to guide development of strategies to mitigate the risks and harms involved. Method The sample consisted of 1,934 active road users (drivers, motorcyclists, cyclists, pedestrians) injured in crashes on South Australian roads who were admitted to the Royal Adelaide Hospital over the period 2014 to 2017. Results The findings indicate that 9.2% of hospital admission cases were directly caused by a medical condition or acute medical event, with loss of consciousness, attempted suicide, and seizures the most commonly observed. Crashes attributed to a medical condition were more likely to involve older drivers and those with a greater number of preexisting medical conditions. Conclusion Medical conditions or acute medical events are a significant contributor to road crashes. Common crash types involving medical conditions or events – single vehicle, hit object – indicate that vehicle technologies such as lane keeping assist and autonomous emergency braking, and infrastructure treatments such as roadside barriers, may help to prevent crashes in which a driver experiences a medical event. Monitoring of drivers with medical conditions should continue, while the benefits of social policies that reduce reliance on private motor vehicles for transport should also be explored.

Dynamic responses of rubberised concrete: A study using short-length F-shape barriers subjected to pendulum impact

This study evaluates rubberised concrete barriers' dynamic responses and failure mechanisms subjected to pendulum impacts. We constructed short-length F-shaped barriers from concrete mixed with varying proportions of steel fibres (0 %, 1 % and 2 %) and recycled crumb rubber (0 %, 30 % and 60 %). These barriers were then tested under controlled pendulum impacts, where we measured their peak impact forces, displacements, and energy absorption capacities at different impact velocities. Our findings reveal that barriers with rubber displayed significantly higher energy absorption and lower peak impact forces at low velocities than standard concrete barriers. Conversely, incorporating steel fibres into rubberised concrete increased the peak impact forces and reduced displacements, indicating enhanced stiffness. The experimental data facilitated the development of a predictive equation for peak impact forces, accounting for impact velocity and material composition. This research demonstrates rubberised concrete's less hazardous failure modes and enhanced impact resistance and energy absorption capabilities when used in roadside barriers. Our findings offer valuable insights for developing safer, more resilient infrastructure and contributing to environmental sustainability by repurposing waste materials.

The impact of vegetative and solid roadway barriers on particulate matter concentration in urban settings.

A potentially important approach for reducing exposure to traffic-related air pollution (TRAP) is the use of roadside barriers to reduce dispersion from highway sources to adjacent populated areas. The Trees Reducing Environmental Exposures (TREE) study investigated the effect of vegetative and solid barriers along major controlled-access highways in Atlanta, Georgia, USA by simultaneously sampling TRAP concentration at roadside locations in front of barriers and at comparison locations down-range. We measured black carbon (BC) mass concentration, particle number concentration (PNC), and the size distribution of ultrafine aerosols. Our sample sites encompassed the range of roadway barrier options in the Atlanta area: simple chain-link fences, solid barriers, and vegetative barriers. We used Generalized Linear Mixed Models (GLMMs) to estimate the effect of barrier type on the ratio of particle concentrations at the comparison site relative to the roadside site while controlling for covariates including wind direction, temperature, relative humidity, traffic volume, and distance to the roadway. Vegetative barriers exhibited the greatest TRAP reduction in terms of BC mass concentration (37% lower behind a vegetative barrier) as well as PNC (6.7% lower), and sensitivity analysis was consistent with this effect being more pronounced when the barrier was downwind of the highway. The ultrafine size distribution was comprised of modestly smaller particles on the highway side of the barrier. Non-highway particle sources were present at all sample sites, most commonly motor vehicle emissions from nearby arterials or secondary streets, which may have obscured the effect of roadside barriers.

An Assessment of the Safety Effects of Roadside Barriers on Reducing Mountainous Crash Injury Severity

Roadside barriers have proven effective in preventing run-off-road accidents that occurred in mountainous areas. Nonetheless, the influence of variables impacting the severity of injuries resulting from collisions involving distinct types of roadside barriers may diverge. This study delves into the factors that influence the severity of driver’s injuries in crashes encompassing three specific varieties of roadside barriers in mountainous regions, namely, W-beam barriers, flexible barriers, and roadside trees. The evolution of these factors over time is examined through the application of a random parameters logit modeling approach with heterogeneity in means and variances (RPLHMVs). By employing injury-severity data from 2016 to 2019 for the mountainous regions of a city in Southwest China, various potential influencing factors encompassing driver-, vehicle-, road-, and environment-specific characteristics are subjected to statistical analysis. The extent of the impact of identified statistically significant factors on driver’s injury severity is assessed through the computation of pseudoelasticities. The findings reveal distinctions in the outcomes of driver’s injury severity contingent upon the type of roadside barrier encountered during vehicle impacts. To illustrate, collisions involving W-beam barriers are more prone to result in severe injuries. Moreover, the influence of variables determining driver’s injury severity displays noteworthy temporal shifts. Notably, the pseudoelasticities of numerous explanatory variables remain temporally consistent for incidents involving flexible or roadside barriers. In contrast, crashes involving W-beam barriers highlight that solely the speeding indicator demonstrates temporally stable pseudoelasticities. The insights garnered from this investigation offer the potential to contribute to the formulation of fresh guidelines for the design and selection of roadside barriers aimed at mitigating the severity of injuries incurred in crashes within mountainous regions.

Resolving the effect of roadside vegetation barriers as a near-road air pollution mitigation strategy

A multi-regime framework adequately resolves the complex physical mechanisms of roadside barriers on near-road air quality in a computationally efficient Gaussian-based model.

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.

Machine learning based centralized dynamic clustering algorithm for energy efficient routing in vehicular ad hoc networks

AbstractVehicular ad hoc network (VANET) is a dynamic and self‐configure wireless network that connects vehicles to provide in‐vehicle infotainment services and comfort to both driver and passengers while on the move. Due to the highly dynamic environment, patchy connectivity, roadside barriers, and a scarcity of road side units (RSUs); existing routing protocols of VANET consume high energy during route construction. As a consequence, the VANET lifespan might be shortened. However, saving energy is a critical factor where VANET is projected to play a key role in the building of sustainable green infrastructure. Clustering is an imperative process where vehicle nodes join to make stable clusters based on common mobility features. In VANET, clustering‐based routing algorithms significantly improve network effectiveness and reduce infrastructure costs. This article proposes fuzzy c‐means (FM) machine learning‐based dynamic clustering algorithm (DCA) to identify trustworthy vehicles for energy‐efficient multi‐hop routing by considering different mobility parameters such as position, direction, speed, and remaining energy of each vehicle node. This article also proposes distance and power‐based variation of FM called fuzzy c‐means using distance and residual power (FMDP) to find stable cluster heads (CHs) for performing better data dissemination to the destination. The proposed DCA outperforms the existing k‐means based clustering algorithms as well as topology‐based DSR and AODV routing protocols in terms of packet delivery ratio, application throughput, end‐to‐end delay, network energy consumption, node energy consumption, and RSU energy consumption. Additionally, clustering methods FM and FMDP of suggested DCA improve end‐to‐end delay by 20%, application throughput by 5%, and reduce network energy consumption by 68% compared with the k‐means based clustering model.

Effect of large bus body reflection on sound barrier efficiency for road traffic noise control: a simulation study

Assessment of road traffic noise (RTN) generally approximates vehicles as point sources, including in the setting of roadside sound barriers (SBs). However, when a large passenger bus passes on a road section with an SB, strong reflected sound waves emerge between the bus body and the SB, reducing the effectiveness of the SB. In this study CadnaA software was used for simulating the sound field distribution formed by such reflections. Because a large bus cannot be approximated as a point source, multi-point noise measurement results of the near-field position of the body of a moving bus were adopted for simulating the actual three-dimensional bus by distributing small-area sources approximately at the near-field different positions near the bus body surface. For a bus moving on a road past an SB, noise distributions were simulated for three scenarios: 1) without an SB, 2) with a smooth reflection-type SB, and 3) with an absorption-type SB. This study presents important insights for establishing RTN SBs.

Incorporating the impact of roadside barrier effects on dispersion into AERMOD

ABSTRACT This paper focuses on the impact of solid barriers located upwind of a highway in reducing vehicle related concentrations that occur downwind of the roadway, compared to a highway without barriers. Measurements made in the United States Environmental Protection Agency’s meteorological wind tunnel show that the mitigating impact of an upwind barrier is comparable to that of a downwind barrier. Upwind barriers lead to reductions in pollution concentrations by drawing emissions in from the highway toward the barrier. The emissions are then entrained into the flow above the recirculation zone and dispersed vertically as they are advected downwind. This upwind transport of vehicle emissions leads to concentrations at the center of the roadways that are roughly 200–300% higher than those measured on roadways with downwind barriers. This difference between on-road concentrations indicates that although both types of barriers mitigate the impact of vehicle emissions downwind of a roadway, the upwind barrier may create adverse air quality impacts for the people on the road. We have formulated a semiempirical dispersion model that incorporates the physics revealed by the wind tunnel measurements. This model improves upon a model proposed by Ahangar et al. (2017) by adjusting the wind speed to get a more realistic plume dispersion just downwind of the upwind barrier and also by providing vertical profiles of concentrations in addition to ground-level concentrations. The upwind barrier model proposed in this paper and the downwind barrier model described in Francisco et al. (2022) have been incorporated into AERMOD (version 21112) as a nonregulatory option, including the new two-barrier option when modeling both barriers on the same roadway. Implications: Our paper presents an air dispersion model algorithm for modeling the effect of upwind noise barriers on dispersion of traffic-related emissions from roadways, which was incorporated into EPA’s AERMOD and then evaluated using observations from a wind tunnel experiment. The results are compared and contrasted with results from both a no-barrier case and downwind barrier cases. This manuscript expands on previously published work analyzing the effect of barrier height and source-to-barrier distance on downwind dispersion (Atmos. Pollut. Res., 13:101385, 2022, https://doi.org/10.1016/j.apr.2022.101385). The current manuscript uses the same wind tunnel setup as reported there, but focuses on a different subset of cases, namely the upwind barrier cases, when developing dispersion model algorithms to simulate the observed effects. We believe the evaluations of the vertical profiles from the wind tunnel study, development, and incorporation of the upwind barrier algorithms into AERMOD, and model evaluation of these new algorithms are significant contributions to understanding the effects of these commonly used roadside barriers

Analisa Kinerja Ruas Jalan Panglima Sudirman Singosari-Malang

Highways are transportation infrastructure that is very important in supporting land transportation. Without being matched by an increase in road infrastructure, it will result in an excessive load on the road structure and will cause congestion. Congestion is one of the problems that is often experienced or encountered, congestion occurs due to the large number of vehicles that exceed the capacity of the road so that it affects road performance. Based on the network pattern seen during holidays or weekends, access to and from the Malang City area tends to increase. Road side barriers that occur on Commander Sudirman street, Singosari are one of the causes of traffic jams. This research aims to provide an alternative plan in overcoming the problem of traffic jams on Commander Sudirman street, Singosari. The method used in this research was based on the 1997 Indonesian Highway Capacity Manual (MKJI), as well as data collection using direct observation methods in the field and then followed by collecting primary data and secondary data. From the research results, the vehicle volume of 2320.6 pcu/hour and degree of saturation (DS) of 0.80 with a level of service (LOS) class D. So it is necessary to divert the route for heavy vehicles (HV) that pass through Commander Sudirman street in the direction of Malang - Surabaya to be diverted via Tumapel street, Ronggowuni street and Kertanegara street, then return to street main route, while for vehicles from Surabaya to Malang that will cross Commander Sudirman street with heavy vehicle types (HV) will follow the current road diversion, namely crossing Rogonoto street, Kebon Agung street, Watu Gede street, and Stasiun street then returning. to the main road as well as installing signs prohibiting parking in the Singosari market shopping area which is on Commander Sudirman street. From the results of this treatment the DS value became 0.76.

Absorptive noise barrier development

This paper reveals the development of an absorptive, self-supporting noise barrier panel for external applications. Designed for use as a temporary external noise barrier for construction sites and roadside noise barriers. The absorptive noise barrier panel is a module base design that is easy to assemble, disassemble, and re-deploy. The barrier panel utilizes recycled plastic materials, such as milk bottles and other soft plastics, making it one of the most environmentally friendly products. The barrier is manufactured in one process via a unique rotation molding method. It is weather resistant, aesthetically appealing, and offers great design flexibility. Standard size panels are 100 mm thick, by 2000 m wide x 500 mm high. The acoustic design is modeled to achieve NRC 0.85 at 100 mm thick based on an advanced air-flow resistive layer technique combined with an air cavity. The actual sound absorption measurement results are well in line with the predicted modeling. Such a case study potentially uncovers a whole new range of innovative absorptive noise barriers. Further studies and investigations are also recommended.

Full-scale analysis of smart fluid-filled barrier technology: Numerical and experimental study of fixture configurations

Roadside barriers are often deployed to prevent vehicles from colliding with roadside obstacles or hazards and from leaving the road surface. These barriers primarily take the form of guardrails or crash cushions and are designed to absorb energy through severe plastic deformation. Due to the severity of these types of collisions, the energy-absorbing mechanisms can fail resulting in the barrier becoming a hazard. To address this issue, a (US Patented) multi-chambered, smart fluid-filled barrier technology (SFFBT) was proposed as a potential replacement for such roadside barriers. This new patented technology utilizes fluid transport between the internal chambers and viscous dissipation as an additional energy-absorbing mechanism to help reduce the effects the severe deformation imparts on the colliding vehicle and its occupants. Numerical models were developed in ABAQUS dynamic explicit environment, and full-scale experimental testing was conducted at the Midwest Roadside Safety Facility of the University of Nebraska—Lincoln. Three barrier configurations were considered for this study with two different fluid levels resulting in six unique test samples. The three test configurations were (a) free-standing, (b) abutted against a rigid backstop, and (c) anchored. Fluid levels chosen were 25% and 33% filled volume. The results show that the proposed designs and fluid addition provided an increase in energy absorption while decreasing overall deformation stroke by up to 5%. Additionally, kinetic energy reduction increased by 15% with a nearly 140% increase in fluid energy dissipation. The best-performing configurations were the rigid backstop cases, followed by anchored and free-standing configurations. The effects of varying anchoring schemes provide additional performance evaluations for maximizing the energy-absorbing performance of the SFFBT system for use as an impact attenuator.

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.

Updated Zone of Intrusion Envelopes in the Manual for Assessing Safety Hardware Impact Conditions

Roadside barriers are used to shield fixed objects near the roadway and are designed to mitigate the severity of run-off-road crashes near those fixed objects. The zone of intrusion (ZOI) defines the potential location of a vehicle component above and beyond the top face of the barrier during an impact, and therefore indicates if there is a potential that a fixed object located behind a barrier could interact with the vehicle during redirection. Previous ZOI envelope guidelines were based on older vehicle models and test results. Further review was required to update the guidelines for contemporary vehicles and impact conditions in accordance with the American Association of State Highway and Transportation Officials (AASHTO) Manual for Assessing Safety Hardware (MASH). A literature review of full-scale crash tests and computer simulations were used to identify the ZOI envelope shapes for MASH test levels 2–5. Simulations were calibrated using test data and were used to investigate gaps in the full-scale test data. Conservative guidelines were developed from the combined simulation and test data, and recommended ZOI envelope shapes were developed that conservatively bounded the ZOI results. Results were presented for potential revision of ZOI envelope guidelines in the AASHTO Roadside Design Guide. Future recommendations to improve ZOI measurements in test data and simulation modeling were also presented.

Developing Safety Performance Functions for Commercial Motor Vehicle Crashes at Interchange Ramp Segments in Kentucky

Compared with roadway segments and intersections, the safety of interchange ramp segments has not been studied extensively, especially in the context of commercial motor vehicles (CMVs). The main objective of this study was to develop a safety performance function (SPF) tool for predicting CMV crashes occurring on interchange ramp segments. Four count models, including the negative binomial (NB), heterogeneous NB (HTNB), standard Conway–Maxwell–Poisson (CMP), and heterogeneous Conway–Maxwell–Poisson (HTCMP), were used and compared while fitting CMV crash-specific SPFs along interchange ramp segments in Kentucky. The HTCMP model, which is an extension of the standard CMP model, is a more flexible approach that handles both over-dispersed and under-dispersed crash data while exhibiting varying dispersion parameters. Five-year (2015 to 2019) CMV-related crashes along Kentucky’s ramp segments were used. The model comparison results showed that the HTCMP significantly outperformed the other three models in crash prediction accuracy and goodness-of-fit statistics (e.g., the Akaike information criterion, Bayesian information criterion, and McFadden’s Pseudo R-squared). The SPF model results using the HTCMP approach indicated that on-ramps (relative to off-ramps), ramp annual average daily traffic, ramp configuration, left shoulder width, ramp gore length, absence of left roadside barrier, and presence of other merging or diverging ramps within the ramp of interest were significantly associated with CMV crash frequency on ramp segments. Potential safety countermeasures were proposed, for example, increasing ramp gore length to be at least 730 ft (since this was associated with a reduction in CMV crashes on ramp segments).

Modeling spatiotemporal interactions in single-vehicle crash severity by road types

Introduction: Spatiotemporal correlations have been widely recognized in single-vehicle (SV) crash severity analysis. However, the interactions between them are rarely explored. The current research proposed a spatiotemporal interaction logit (STI-logit) model to regression SV crash severity using observations in Shandong, China. Method: Two representative regression patterns-mixture component and Gaussian conditional autoregression (CAR)-were employed separately to characterize the spatiotemporal interactions. Two existing statistical techniques-spatiotemporal logit and random parameters logit-were also calibrated and compared with the proposed approach with the aim of highlighting the best one. In addition, three road types-arterial road, secondary road, and branch road-were modeled separately to clarify the variable influence of contributors on crash severity. Results: The calibration results indicate that the STI-logit model outperforms other crash models, highlighting that comprehensively accommodating spatiotemporal correlations and their interactions is a recommended crash modeling approach. Additionally, the STI-logit using mixture component fits crash observations better than that using Gaussian CAR and this finding remains stable across road types, suggesting that simultaneously accommodating stable and unstable spatiotemporal risk patterns can further strengthen model fit. According to the significance of risk factors, there is a significant positive correlation between distracted diving, drunk driving, motorcycle, dark (without street lighting), and collision with fixed object and serious SV crashes. Truck and collision with pedestrian significantly mitigate the likelihood of serious SV crashes. Interestingly, the coefficient of roadside hard barrier is significant and positive in branch road model, but it is not significant in arterial road model and secondary road model. Practical Applications: These findings provide a superior modeling framework and various significant contributors, which are beneficial for mitigating the risk of serious crashes.

Method for Enhancing Performance of Old Roadside Barrier Installed on Highway

Method for Enhancing Performance of Old Roadside Barrier Installed on Highway

Aerodynamic characteristics and structural behavior of sound barrier under vehicle-induced flow for five typical vehicles

Running vehicles cause disturbances in the surrounding air, which lead to a vehicle-induced aerodynamic load (VIAL) on roadside thin-wall structures. In this study, to reveal the aerodynamic load mechanism on roadside sound barriers subjected to the action of a vehicle-induced airflow, the Computational Fluid Dynamics(CFD) method is used to simulate the airflow around a running vehicle and adjacent to the sound barrier. First, the reliability of the numerical simulation is verified by comparing it with field tests. Second, using the CFD method, flow fields around the running vehicle with and without a sound barrier are obtained, the wind-pressure distribution is extracted, and the micro-mechanism of the sound barrier’s influence on the airflow around the running vehicle is revealed by comparing and analyzing the flow-field distribution characteristics. Thirdly, through parametric studies, the changing rules of the wind-pressure distribution and the VIAL effect of internal force on the sound barrier screen are presented under different conditions, i.e., sound barrier height, vehicle shape, vehicle–barrier separation distance, and sound barrier shape. Then, using the FEM method, the load effect of vehicle-induced airflow on the sound barrier column is revealed. The conclusions improve the understanding of the action mechanisms of the vehicle-induced airflow on roadside sound barriers.