Analysis of Chloride Deterioration and Structural Safety Evaluation of Bridge Barriers

Recently, there has been an increase in the chloride deterioration of bridges on urban highways owing to the excessive usage of deicing agents in winter, thus necessitating repair and maintenance measures to ensure the durability of concrete. In this study, the status of the damages occurring in the concrete barriers, such as walls and median partitions, of bridges on urban highways in Seoul was investigated. After collecting a total of 306 cores from various sites, a chloride analysis test was performed on a total of 918 samples obtained by dividing each core into three parts. The results were analyzed using the depth, upper and lower parts of the barrier, damage conditions, and route. In addition, the safety of the structure was evaluated in the case of repair by removing the corroded reinforcing bars (main reinforcing bars and spacers) directly exposed to chloride.

Comparison of Modified Yield-Line and Punching Shear Capacities for Concrete Traffic Barriers and Bridge Rails

The traditional, triangular yield-line method used by most departments of transportation for analyzing concrete traffic barriers and bridge rails has been largely unchanged since 1978. Testing of concrete barriers since this time has indicated that the triangular yield-line method is not qualitatively representative of observed damage patterns and is overconservative. Further, the conversion from NCHRP Report 350 to the crash test criteria from the Manual for Assessing Safety Hardware (MASH) will result in increases to lateral impact loads; therefore, overconservative analysis practices may result in many concrete barriers being unnecessarily deemed inadequate. In this research, alternative analysis methods for concrete barriers were extracted from an extensive literature review of concrete barrier investigations. These methods were applied to a sample of eight concrete barriers to demonstrate and compare their effects on capacity estimates. Alternative methods included trapezoidal yield-line mechanisms, effects of impact heights lower than the top of the barrier, punching shear evaluation, and consideration of expected material strengths. Capacity estimates of the selected barriers were increased by an average of 47 percent when alternative methods were cumulatively applied. Although the traditional method does not consider punching shear, the capacity of one of the eight barriers was controlled by punching shear rather than by yield-line flexure. With the alternative methods applied, seven of the eight barriers were deemed adequate relative to the increased lateral loads corresponding to MASH criteria for Test Levels 2 through 5. By contrast, if analyzed according to the traditional method, three of the eight barriers would have been deemed insufficient considering MASH loads.

A Study on Sustainable Reutilization of C&D Debris in the Construction of Traffic Barrier

In India, the construction industry is growing at twice the world average. This leads to a significant accumulation of C&D waste. This typically includes asphalt, steel, concrete, bricks, wood and other building materials. It is estimated on a conservative basis that over 25-30 million tons of C&D waste is generated which clogs rivers, blocks traffic and occupies land / agricultural space which in turn creates pollution, solid waste production, discharge of dust and gas and leads to additional utilization of natural resources including non-renewable resources, thereby depleting the available resources. Only little amount of construction and demolition concrete debris is recycled or reused. Construction and demolition waste generation and handling issues are being focused to achieve sustainable goals. Based on this study, experimental investigations are carried out to evaluate the material properties and to study the strength characteristics and effect of partial replacement (20 %, 30 % and 40 %) of both fine and coarse aggregate obtained from construction and demolition waste (CDW) in the construction of intermediate road traffic concrete barriers.

Caregiver Perspectives of Pre-Transplant Evaluation in Children

Pre-transplant evaluation is mandated by Centers for Medicare and Medicaid Services, but there is wide institutional variation in implementation, and the family experience of the process is incompletely understood. Current literature largely focuses on adult transplant recipients. This qualitative study begins to fill the knowledge gap about family experience of the pre-transplant evaluation for children through interviews with caregivers at a large pediatric transplant center. Prominent themes heard from caregivers include (1) the pre-transplant evaluation is overwhelming and emotional, (2) prior experiences and background knowledge frame the evaluation experience, and (3) frustration with communication among teams is common. These findings are relevant to efforts by transplant centers to optimize information delivery, minimize concrete barriers, and address healthcare systems issues.

Examining Driver Injury Severity in Single-Vehicle Road Departure Crashes Involving Large Trucks

Road departure (RD) crashes are among the most severe crashes that can result in fatal or serious injuries, especially when involving large trucks. Most previous studies neglected to incorporate both roadside and median hazards into large-truck RD crash severity analysis. The objective of this study was to identify the significant factors affecting driver injury severity in single-vehicle RD crashes involving large trucks. A random-parameters ordered probit (RPOP) model was developed using extensive crash data collected on roadways in the state of Kentucky between 2015 and 2019. The RPOP model results showed that the effect of local roadways, the natural logarithm of annual average daily traffic (AADT), the presence of median concrete barriers, cable barrier-involved collisions, and dry surfaces were found to be random across the crash observations. The results also showed that older drivers, ejected drivers, and drivers trapped in their truck were more likely to sustain severe single-vehicle RD crashes. Other variables increasing the probability of driver injury severity have included rural areas, dry road surfaces, higher speed limits, single-unit truck types, principal arterials, overturning-consequences, truck fire occurrence, segments with median concrete barriers, and roadside fixed object strikes. On the other hand, wearing seatbelt, local roads and minor collectors, higher AADT, and hitting median cable barriers were associated with lower injury severities. Potential safety countermeasures from the study findings include installing median cable barriers and flattening steep roadside embankments along those roadway stretches with high history of RD large-truck-related crashes.

The Social Life of a Barrier: A Material Ethnography of Urban Counter-terrorism

In the aftermath of the truck attacks in Berlin, Nice, Paris, and Stockholm, new counter-terrorism measures are being installed in European city centers. Through an ethnographic approach, this article explores the socio-material effects triggered by the most conspicuous material responses to hostile vehicle treats: concrete barriers. We draw on the recent turn towards mobilities design thinking to address the béton barriers as more-than physical obstructions, but designed artefacts negotiated and re-appropriated in unexpected ways. Set in the context of Copenhagen, we explore how the concrete barriers reveal the social, cultural, and practical conditions of the city. By establishing a critical mobilities design-oriented understanding of counter-terrorism “in situ,” we seek to broaden out what the process of “designing out terrorism” entails and to discuss new participatory design processes for future transformations of the city in light of terrorism threats.