Bridge Closure Research Articles

Comparison of outcomes of idiopathic macular holes treated by vitrectomy with air or silicone oil tamponade based on the hole size.

To compare the efficacy of vitrectomy combined with air or silicone oil in the treatment of idiopathic macular hole (IMH). According to the results of high-definition optical coherence tomography (HD-OCT), 75 cases (75 eyes) of IMH in stage II-IV (Gass stage) in the General Hospital of Chinese PLA from January 2017 to December 2019 were collected for this retrospective study. The best corrected visual acuity (BCVA) and minimum diameter of IMH (MMHD) were measured. Eyes underwent vitrectomy combined with internal limiting membrane peeling operation, and were divided into disinfection air group (30 eyes) and silicone oil group (45 eyes) according to the intraocular tamponade. For MMHD≤400 µm (MMHD1), there were 23 eyes in air group and 16 eyes in silicone oil group. For MMHD2>400 µm (MMHD2), there were 7 eyes in air group and 29 eyes in silicone oil group. One month after surgery, the closure rates of IMH and BCVA were compared and analyzed. According to HD-OCT, the closure shape was graded with A (bridge closure) and B (good closure). The closure rates of air group and silicone oil group were 86.67% and 95.56% respectively with no significant difference (P>0.05); For MMHD1, those of air group and silicone oil group were 95.65% and 100% respectively with no significant difference (P>0.05); For MMHD2, those of air group and silicone oil group were 57.14% and 93.10% respectively, and those of the silicone oil group were higher than the air group (P<0.05). There was no significant difference in the closure shape grade between MMHD1 air group and silicone oil group (P>0.05). The proportion of Grade B in MMHD2 silicone oil group was higher than that in the air group (P<0.05). BCVA of each group after operation was better than that before operation, and there was no significant difference between air group and silicone oil group. While among them, MMHD1 air group was better than silicone oil group (P<0.05), and there was no significant difference between MMHD2 air group and silicone oil group (P>0.05). For smaller IMH (≤400 µm), the efficacy of vitrectomy combined with air should be considered better than silicone oil; for larger IMH (>400 µm), the efficacy of silicone oil may be better than air.

Critical decisions in hurricane evacuation bridge and roadway closures.

The closure of bridges and roadways during hurricanes can represent an abrupt end to evacuations for the resi-dents of coastal barrier island. Despite the gravity of bridge and roadway closures during hurricane evacuations, their governing policies and practices in the United States are often opaque, poorly defined, or mired in confusion. The lack of clarity among bridge and roadway closure policy rationales and terminology, as well as their wide dissensus, may disrupt public compliance and participation in hurricane evacuations. This article argues for the application of critical decision methods (CDMs) analysis in hurricane evacuation bridge and roadways closures as a means of producing better, evidence-based policies and practices. Using CDM to study the decision-making of the experts responsible for the actual work of closing bridges and roadways in hurricane evacuations can help produce more detailed, evi-dence-based policies, more compelling communication about those policies, and greater public compliance in hurricane evacuations.

A monitoring-based classification system for risk management of bridge scour

Flood-induced scour is the principal cause of bridge failure worldwide. Nevertheless, bridge scour risk assessment is still based on visual inspections, which may be affected by human errors and cannot be performed during flood peaks. This problem, together with the simplifications in scour estimation, might cause misclassification of the bridge scour risk, unnecessary bridge closures or recourse to avoidable scour mitigation measures. Structural-health-monitoring (SHM) systems allow overcoming these issues, providing bridge managers with more accurate information about scour, thus supporting them in taking optimal management decisions. This paper illustrates the development of an SHM- and event-based classification system for bridge scour management, which extends and complements current risk-rating procedures by incorporating the various sources of uncertainty characterising the scour estimation and information from different sensors. The proposed system is based on a probabilistic framework for scour risk estimation and can be used to provide transport agencies with real-time scour risk classification of bridges under a heavy-flood event. The system is applied to a bridge network located in south-west Scotland in a heavy-flood scenario, and information from heterogeneous sources is considered for updating the knowledge of scour. It is shown that integrating scour-monitoring data leads to an overall uncertainty reduction that is reflected in more accurate scour risk classification, thus helping transport agencies in prioritising bridge inspections and risk mitigation actions.

A Closure Jacking Force Calculation Algorithm for Curved Prestressed Concrete Continuous Rigid-Frame Bridges with Asymmetric Cantilevers and Piers

Concrete continuous rigid-frame bridges are the most commonly used to cross exciting highway and railway. Before the bridge closure, the closure jacking force (CJF) needs to be determined firstly, which plays an important role in mid-span deflection controlling and the whole bridge stress state. This study proposed a closure jacking force calculation algorithm for curved prestressed concrete continuous rigid-frame bridges with asymmetric cantilevers and piers. Firstly, the mechanics method was used to analyze the relationship between the CJF and normal stress of main-girder and the pier. In addition, an actual bridge was taken as a numerical simulation case to determine the influence of the deformation and the stress induced by concrete shrinkage and creep of the main-girder and the jacking force. Finally, in order to obtain the optimal stress state of bridge piers, the multi-objective linear programming method was proposed to calculate the CJF. The results show that curved prestressed concrete continuous rigid-frame bridges usually suffered longitudinal and transverse bending and torsion under the concrete shrinkage and creep of the main-girder and the CJF, and the CJF significantly affected the normal stress of the pier with a low anti-push rigidity. The normal stress of piers was obviously linear with the CJF during whole construction and operation state of bridges at the following three states: the jacking process, bridge completion, and ten years of bridge operation. The multi-objective linear programming algorithm was an effective way to determine the optimal CJF and can fully reflect both longitudinal and transverse bending of piers.

Impact of the temporary closure of a major bridge on local air quality in two large German cities: an accountability study

Despite recent achievements in reducing the contribution of road traffic to air pollution, agreed pollutant standards are exceeded frequently in large parts of Europe. Previous studies assessed the effectiveness of traffic interventions in improving local air quality. However, little research exists on the effect of closures of short road sections over longer periods. The multi-week maintenances on the Theodor Heuss Bridge, the main connection over the river Rhine between the German cities Mainz and Wiesbaden, offered the opportunity to investigate its effect on local air pollution. We measured ambient concentrations of major air pollutants and meteorological parameters at the Theodor Heuss Bridge before, during, and after its closure on 800 m in early 2020. We carried out time-series and closure-dependent evaluations of pollutant concentrations at the bridge accounting for wind direction. Furthermore, we performed regression analyses accounting for wind speed additionally. We compared the results with data from surrounding monitoring stations. We recorded higher concentrations at the Theodor Heuss Bridge compared to outside the closure, especially for particulate matter, nitric oxide, and black carbon. Only with wind from specific directions, we could detect reductions of concentrations during the closure for many pollutants as nitrogen dioxide (− 9.8%; 95% confidence interval: − 10.8– − 8.7%), but not for particulate matter. Since we found similar meteorology-dependent pollution reductions during the closure at both the bridge and the surrounding monitoring stations, we assume that regional meteorological factors overlaid a potential closure-related effect on local air quality. These factors must be accounted for in accountability studies on interventions focusing on short roads.

Cross-flow aerodynamics of bridge cables with wire meshes

Adverse weather conditions in the northern regions during winter might lead to accumulation of ice or snow on bridge cables and consequently trigger ice shedding. The falling ice poses a risk for the traffic and pedestrians below, which often results in bridge closures and/or insurance claims. A passive surface-modifying device in the form of a steel wire mesh tautened on the surface of a cable sheath was previously found to substantially reduce the risk associated with falling ice through improved ice retention. In this paper, the cross-flow aerodynamic behaviour of bridge cables fitted with steel wire meshes is investigated in detail. The wire mesh generally resulted in higher levels of aerodynamic drag when compared with a plain cable sheath, although the Reynolds number dependence was highly reduced. Several angles of attack were investigated and no instability issues with respect to the across-wind vibrations were observed for any of the tested wire mesh configurations based on the quasi-steady theory. Even though vortex shedding was still present in all cases, the intensity of the fluctuating lift forces was much lower than that of the plain cable. To investigate basic aspects of the flow structure produced by the wire mesh, two flow visualisation techniques, combined with streamwise wind speed measurements in the near wake, were further used and are discussed.

Bridge closure in the road network of Lombardy: a spatio-temporal analysis of the socio-economic impacts

This paper introduces a methodology to evaluate the socio-economic impacts of closure for maintenance of one or more infrastructures of a large and complex road network. Motivated by a collaboration with Regione Lombardia, we focus on a subset of bridges in the region, although we aim at developing a method scalable to all road infrastructures of the regional network, consisting of more than 10,000 tunnels, bridges and overpasses. The final aim of the endeavor is to help decision-makers in prioritizing their interventions for maintaining and repairing infrastructure segments. We develop two different levels of impact assessment, both providing a unique global score for each bridge closure and investigating its spatio-temporal effects on mobility. We take advantage of a functional data analysis approach enhanced by a complex network theory perspective, thus modelling the roads of Lombardy as a network in which weights attributed to the edges are functional data. Results reveal the most critical bridges of Lombardy; moreover, for each bridge closure, the most impactful hours of the day and the most impacted municipalities of the region are identified. The proposed approach develops a flexible and scalable method for monitoring infrastructures of large and complex road networks.

Does traffic really disappear when roads are closed?

This paper describes two studies that aimed to explore the impacts of pedestrianisation or road closures on traffic displacement, travel behaviour and the phenomenon of ‘disappearing traffic’. The first study surveyed residents whose travel routes were affected by a small-scale localised pedestrianisation scheme in the centre of a town. The second measured the traffic impacts of a temporary closure of a strategic bridge in a city centre. In the first case, the pedestrianisation produced no change in the modal shares of travel of residents. Drivers continued to drive to the same locations by longer routes. In the second case, the closure caused some traffic displacement and increased journey times but also reduced traffic volumes in both the immediate area and across the city. This paper concludes by discussing the remaining knowledge gaps on disappearing traffic, made more pressing by the decisions of authorities to reallocate road space during the coronavirus disease 2019 crisis.

Bridge and transport network resilience – a perspective

Bridges and critical transport infrastructure are primary assets and systems that underpin human mobility and activities. Loss of bridge functionality has consequences on entire transport networks, which are also interconnected with other networks. Cascading events then unfold in the entire system of systems, leading to significant economic losses and societal disruption to business and society. Recent natural disasters have revealed the vulnerabilities of bridges and critical assets to diverse hazards (e.g. floods, blasts, earthquakes), some of which are exacerbated due to climate change. The assessment of bridge and network vulnerabilities by quantifying their capacity and functionality loss and adaptation to new requirements and stressors is thus of paramount importance. The aim of this work was try to understand the main compound hazards, stressors and threats that have short- and long-term impacts on the structural capacity and functionality of bridges and the impact of bridge closures on network operability. The main drivers of bridge restoration and reinstatement were also considered. Loss of performance, driven by redundancy and robustness of a bridge, is the first step to be considered in the overall process of resilience quantification. Resourcefulness is the other main component of resilience analysed in this work.

A direct method to detect and localise damage using longitudinal data of ends-of-span rotations under live traffic loading

Existing work on rotation-based bridge monitoring has focused on indirect methods, such as bridge weigh-in-motion or influence line approaches. However, these approaches require increased instrumentation complexity, and require calibration, necessitating bridge closures. In this paper, we explore the potential of using rotation measurements to create a more practical and cost-effective monitoring system. To this end, we present a damage detection method which directly analyses bridge rotation data measured under live, free-flow traffic loading. We show how the Earth Mover’s Distance, typically used in statistics and image processing, can be applied directly on end-of-span rotation measurement data to achieve effective damage detection and localisation. Numerical simulation results demonstrate the approach’s robustness to the confounding effects of temperature variation and traffic diversity (vehicle type, loading, and velocity). The direct rotation measurement approach is applied to data from an in-service short-span bridge to demonstrate the technique’s capability with free-flow traffic loading.

Laboratory and numerical investigation of integral abutment connections with pile couplers

By benefiting from precast structural elements, accelerated bridge construction (ABC) strategies have received growing attention, as they can alleviate the consequences of prolonged bridge closures caused by cast-in-place (CIP) construction methods. Among various precast elements, integral abutments are commonly employed to eliminate the expansion joint between a bridge’s substructure and superstructure, where the ingress of aggressive ions often requires frequent maintenance and repair. Due to the heavy reinforcement required at the bridge end region, congestion issues often arise, especially when attempting to utilize ABC. To address such issues, this study focuses on the integral abutment connection details designed with a set of pile couplers that splice the integral abutment diaphragm to the pile cap. The investigations involve full-scale laboratory experiments conducted to understand the structural response of the proposed connection details under both thermal and live loads. The main response measures obtained from the conducted tests were then compared to those recorded during a full-scale test on a CIP integral abutment with the details that represented the conventional design and construction practices. Upon completing the laboratory investigations, a series of numerical simulations were performed to evaluate the most critical connection details. The simulations explored a range of steel sections and a proposed design revision, in which the pile couplers were replaced with a bar reinforcement cage. The outcome of this study helps the bridge industry effectively use pile couplers for integral abutment connections, especially for ABC applications.

Formula omitted] Emission based prioritization of bridge maintenance projects using neutrosophic fuzzy sets based decision making approach

Climate change is one of the most challenging problems for the world, which leads researchers to study on the decrease of its impact to the environment at several disciplines. One of the most adverse effects on environment can be observed in transportation area. Hence, in this paper, the impact of bridge maintenance on the environment is inquired in the bridge maintenance prioritization perspective. The aim of this paper is to rank the bridge maintenance projects using type-2 neutrosophic number (T2NN) based fuzzy WASPAS (Weighted Aggregated Sum Product Assessment) and TOPSIS (Technique For Order Preference By Similarity To An Ideal Solution) to test five alternative bridges, where a critical environmental criterion is introduced in this model, which addresses to additional CO2 emission because of truck detours in the event of a bridge closures. The applicability of the proposed model is demonstrated in a case study in Turkey. The evaluation findings show that the ranking results are robust and the CO2 emission criterion is found to be the dominant criterion in the multi-criteria decision-making model proposed in this paper.

Economic impact of bridge functionality loss from a resilience perspective: Queensferry Crossing, UK

Understanding the resilience of transport networks is critical for efficient asset management. This paper takes an innovative approach to studying the operability of the Queensferry Crossing (QFC), UK, including cost–benefit aspects. A key driver for the QFC was to increase the resilience of the A90/M90 link by reducing weather-related closures. The first weather-related closure of the QFC was in February 2020, when ice formed on the superstructure cables and fell on the carriageway and vehicles, creating a safety risk for bridge users. The bridge was closed for 41 h and, in this paper, the estimated monetary losses are compared with those of past Forth Road Bridge (FRB) closures. The costs of potential mitigation measures are then assessed in the context of closure costs, thus improving the resilience of the QFC. Although the QFC has only been open for 3 years, it is already apparent that it is significantly more resilient than the largely replaced FRB, whether this is considered as the number, duration or costs of closures and that this will be substantially improved by the planned use of the FRB during future closures of the QFC. Investment in mitigation measures is a potentially cost-effective solution although the form of any suitable ice prevention or removal system is, as yet, far from clear.

Rekayasa Lalu Lintas Pada Kawasan Simpang Jl. Lingkar Tengah – Jl. DR. Leimena Di Kota Makassar

Transportation problem, either in general or specifically in traffic, is a phenomenon occuring in human life. As the population of city increased, so does the traffic rate. If this is not followed by adequate improvement of transportation infrastructure, an imbalance might occur which will result in traffic jam. It can be seen particularly at Lingkar Tengah – Dr. Leimena road junction connecting Jalan Perintis Kemerdekaan - Dr Leimena road due to driver/rider against the direction. Data analysis and planning using method of road capacity manual (MKJI 1997) and the traffic modelling using PTV Vissim. Based on road performance analysis it is known that DS (degree of saturation) is 0.12 with service level ‗A‘ and average speed ≥23km/h with service level ‗D‘. From the calculation result, modelling is conducted using PTV Vissim modelling. Alternative for handling the intersection is using 2 methods, which are traffic light signaling for 3 phases with immediate straight at west corner and immediate left turning at east corner and bridge closure on Dr. Leimena road. Using PTV Vissim, the result is that intensity of travel time increases about 47.68% and 57.40% on the intersection.

Design and construction of the Tahya Misr cable-stayed bridge in Cairo, Egypt

The 540 m Tahya Misr Bridge over the Nile in Cairo, Egypt was completed in 2019. At 67.3 m wide, it is the widest cable-stayed crossing in the world. The crossing has an innovative configuration, with separate decks for each carriageway carried by merged pylons that share their inner legs. This paper highlights the unique design features and special construction considerations of the shared-pylon design. The geometry and site control strategies are explained along with the bridge closure process, which was based on the natural temperature method.

Life-cycle cost assessment of conventional and hybrid sliding-rocking bridges in seismic areas

This article investigates the impacts of the column system on bridge life-cycle costs in high seismic areas. It focuses on hybrid sliding-rocking (HSR) columns, which are an accelerated bridge construction (ABC) technology. The authors conduct a life-cycle cost assessment, quantifying costs of bridge construction and potential earthquake damage and subsequent repairs, as well as the cost of bridge closure time due to construction or repairs. Two prototypical modern seismically designed bridges are considered, each designed with both conventional reinforced concrete (RC) and HSR columns. Construction costs of HSR columns are higher. However, drift demands on the HSR columns are generally lower, damage is less severe and costs of repairing the columns are greatly reduced. Moreover, construction times are about 80% quicker for HSR columns, and repair times are reduced relative to conventional construction. The results suggest substantial advantages to the HSR column system, reducing construction time and expected costs and time for seismic repairs sufficiently to counteract the increase in upfront construction costs. The benefits of the HSR, and by extension other ABC column systems, are particularly significant for highly trafficked bridges in high seismic areas, but hold for a wide range of input assumptions.

A framework for assessing the value of information for health monitoring of scoured bridges

It is generally accepted that climate change is leading to increased frequency of extreme weather events worldwide, and this is placing heavier demands on an already aging infrastructure-network. Bridges are particularly vulnerable infrastructure assets that are prone to damage or failure from climate-related actions. In particular, bridges over waterways can be adversely affected by flooding, specifically the washing away of foundation soils, a mechanism known as scour erosion. Scour is the leading cause of failure for bridges with foundations in water as it can rapidly compromise foundation stiffness often resulting in unacceptable movements or even collapse. There is growing interest among asset managers in applying health monitoring approaches to assess the real-time performance of bridges under damaging actions, including scour. Sensor-based approaches involve the acquisition of data such as dynamic measurements, which can be used to infer the existence of scour or other damage without the laborious requirements of undertaking visual inspections. In this paper, a framework is proposed to assess the benefit obtained from health monitoring systems as compared to the scenario where no monitoring system is employed on a bridge, to ascertain how useful these systems are at assisting decision-making. Decisions typically relate to the implementation of traffic restrictions or even partial or complete bridge closure in the event of damage being detected, which has associated consequences for a network. A case study is presented to demonstrate the approach postulated in this paper.

Impact of Coastal Hazards on Residents’ Spatial Accessibility to Health Services

The mobility of residents and their access to essential services can be highly affected by transportation network closures that occur during and after coastal hazard events. Few studies have used geographic information systems coupled with infrastructure vulnerability models to explore how spatial accessibility to goods and services shifts after a hurricane. Models that explore spatial accessibility to health services are particularly lacking. This study provides a framework to examine how the disruption of transportation networks during and after a hurricane can impact a residents ability to access health services over time. Two different bridge closure conditions, inundation and structural failure, along with roadway inundation are used to quantify post-hurricane accessibility at short- and long-term temporal scales. Inundation may close a bridge for hours or days, but a structural failure may close a route for weeks or months. Both forms of closure are incorporated using probabilistic vulnerability models coupled with GIS-based models to assess spatial accessibility in the aftermath of a coastal hazard. Harris County, an area in Southeastern Texas prone to coastal hazards, is used as a case study. The results indicate changes in the accessibility scores of specific areas depending on the temporal scale of interest and intensity of the hazard scenario. Sociodemographic indicators are also examined for the study region, revealing the populations most likely to suffer from lack of accessibility. Overall, the presented framework helps to understand how both short-term functionality loss and long-term damage affect access to critical services such as health care after a hazard. This information, in turn, can shape decisions about future mitigation and planning efforts, while the presented framework can be expanded to other hazard-prone areas.

Decision tree based bridge restoration models for extreme event performance assessment of regional road networks

Bridge restoration models are essential for assessing the functionality of bridges after extreme events, emergency response planning, and evaluating resilience and indirect losses. Most of the existing restoration models lack explicit evaluation of anticipated bridge functionality in terms of traffic restrictions on bridges, which is necessary for realistic road network modeling. Therefore, this paper proposes a decision tree based approach to determine potential traffic restrictions and their durations using empirical and expert opinion survey data on restrictions imposed on bridges after extreme events. The proposed methodology is applied in this paper to obtain seismic restoration models for bridges. Herein, three separate decision trees are developed to determine various traffic restrictions, anticipated for different levels of damage to bridge components, including bridge closure, lane closure, and speed/load restriction. Corresponding to each of the three traffic restriction decision trees, another decision tree is developed which determines the duration of the traffic restriction. The probabilistic seismic performance of a regional highway network in Memphis, Tennessee, is studied using the proposed decision trees. Additionally, HAZUS bridge restoration functions are also applied and the differences in the time evolving bridge level functionality estimates and their impacts on network performance are highlighted.

Winter monitoring of damaged bridges: learning from the December 2015 floods in Cumbria, UK

The December 2015 storms resulted in unprecedented damage to bridges in Northern England, UK. In Cumbria, the inspection of lower-priority structures was then delayed by continuing high water levels and the need to prioritise scarce diving resources to the repair works. Thus, full inspections were not completed until after the end of the summer river access period, leaving over 180 bridges that could not be repaired because rising river levels prevented safe access. This paper describes the risk-based strategy adopted to manage the monitoring and urgent repair of damaged bridges during the winter of 2016/2017. The strategy combined the engineering assessment of bridge condition and catchment-based river-level informatics to provide duty engineers with timely warning of river flows deemed likely to cause further risk, thus enabling them to call out inspection and maintenance engineers to assess the risks on-site and, where necessary, assure public safety by initiating bridge closures. The lessons learnt from the implementation of this strategy on this 10% sample of Cumbria’s bridge stock will be used to inform the selection of measures for resilience against the effects of climate change and to develop county-wide emergency preparedness processes for all the highways network structures.