Bridge Closure Research Articles

How do transport costs affect firms’ exports? Evidence from a vanishing bridge

In this paper we provide estimates of the effects of international transport costs on firms’ exports and disentangle the channels of these effects. In so doing, we use a unique dataset consisting of highly disaggregated transaction-level trade and transport cost data and, in order to account for endogeneity, we exploit the exogenous variation in these costs associated with the non-trade related closure of the main bridge connecting two countries.

Vortex-Induced Vibrations on Cross Sections in Tandem Arrangement

The progressive increase in the construction of long-span bridges in recent years has led to an increasingly detailed study of the aeroelastic effects observed for structural components such as decks, towers and cables. The greater flexibility due to larger spans and optimized cross sections result in critical wind speeds below the design wind speed and would have therefore a certain probability of occurrence during the service life. Such critical wind speeds should be increased by introducing some modification on the cross section geometry.Cables for suspension and cable-stayed bridges are subject to vibrations caused by galloping or gust effects, though these typically occur at high wind speeds. Flutter instability is driven by a fundamental vertical and torsional mode coupling at very high wind speeds. On the contrary, vortex-induced vibrations (VIV) are associated with a single vibration mode and are characteristic of a lower wind speed range. Vortex shedding causes amplitude-limited oscillations, as VIV is not aeroelastic instability. However, it can pose a danger to the structural integrity of the deck or discomfort to users, which would require the temporary bridge closure. Towers of cable-stayed and suspension bridges can also suffer this type of aeroelastic phenomenon.This paper examines the VIV phenomena on towers and decks in tandem configuration by computational fluid dynamic (CFD) methods and experimental wind tunnel tests. This paper specifically discusses the influence of the gap that separates the two main sections and the presence of obstacles, as bracing elements, that affect the fluid–structure interaction and thus their aerodynamic properties. The choice of a proper geometry in the design stage can avoid such low-wind speed vibrations on sections in tandem arrangement.

Influence of Holocene environmental change and anthropogenic impact on the diversity and distribution of roe deer

Extant patterns of population structure and levels of diversity are a consequence of factors that vary in both space and time. Our objective in this study is to investigate a species that has responded to both natural and anthropogenic changes in ways that have shaped modern populations and provide insight into the key processes. The roe deer (Capreolus capreolus) is one of the two species of deer native to Britain. During the last glacial maximum (LGM), the British habitat was largely under ice and there was a land bridge to mainland Europe. As the Earth warmed during the early Holocene, the land bridge was lost. Subsequent hunting on the British mainland left the southern region extirpated of roe deer, whereas a refugial population remained in the north. Later reintroductions from Europe led to population expansion, especially in southern United Kingdom. Here, we combine data from ancient and modern DNA to track population dynamics and patterns of connectivity, and test hypotheses about the influence of natural and anthropogenic environmental change. We find that past expansion and divergence events coincided with a warming environment and the subsequent closure of the land bridge between Europe and the United Kingdom. We also find turnover in British roe deer haplotypes between the late-Holocene and modern day that have likely resulted from recent human disturbance activities such as habitat perturbation, overhunting and restocking.

Economic Impact of Closing Structurally Deficient or Functionally Obsolete Bridges on Very Low-Volume Roads

The state of Kansas has approximately 25,464 bridges located on state, county, and city roadway networks. As of May 2012 approximately 1,229 bridges on very low-volume roads were determined to be structurally deficient and candidate structures to be potentially closed, replaced, or repaired. This study was designed to provide such critical information for county commissioners or practicing engineers as (a) where structurally deficient or functionally obsolete bridges on low-volume roads were located, (b) what distance was the shortest drivable detour if these bridges were to be closed, and (c) whether to recommend closing or to repair or replace the structurally deficient bridges on the basis of both potential detour length and average daily traffic (ADT). The results of the study indicated that many of the structurally deficient bridges on very low-volume roadways had detours of 2 mi or less, were steel bridges, and had ADT values of fewer than eight vehicles. On the basis of the analysis, bridge closure was recommended for a low-volume roadway with an ADT value less than eight and a detour length of less than 9 mi.

Design of railway bridges considering life-cycle assessment

The world is currently confronted with the challenge of preventing environmental degradation and resource depletion. To compare the environmental performance of two railway bridge designs, an Excel-based model was developed with implementing a simplified quantitative life-cycle assessment. The model covers the entire life cycle of the bridge, from raw material extraction to construction materials recycling and disposal. Various assumptions are made for selecting the relevant emissions and environmental impacts. A streamlined approach is applied to compare the environmental burden throughout the life cycle of the Banafjäl Railway Bridge. The bridge is a simply supported composite structure carrying one railway track. Two track alternatives are investigated: ballasted track and fixed track. The results show that the environmental impacts of the fixed track alternative are lower than those of the ballasted track alternative. From a sustainable development perspective, it appears that fixed track has a significant advantage as the overall environmental impact is reduced by up to 77%. The raw material phase is found to be decisive in the life cycle of both alternatives. The frequency of track replacement is identified as a key environmental parameter, because the extra environmental burden of traffic delay during bridge closure nearly overwhelmed the other life-cycle stages.

Analysis of Bursting Crack of Bottom Slab and Reinforcement for a Large Continuous Girder Bridge

A large railway bridge is using (46.4 + 64 + 46.4) m double-line prestressed concrete continuous girder. In the construction process, bottom slab concrete in the mid span appears serious bursting crack phenomenon. Through the whole bridge stress analysis and closure segments locally fine finite element stress analysis, it appears tensile stress and large compressive stress in operational stage. Finally the bottom slab reinforcing schemes are proposed. It makes the following conclusions by analysis: (1) through the overall and local analysis stresses meeting the design requirements after reinforcement; (2) according to the domestic and foreign research experience, bursting crack reason of bottom slab is that prestressed pipes deviation from the design positions and anti-collapse steel bars are not set in place.

Historical biogeography of Eastern Asian–Eastern North American disjunct Melaphidina aphids (Hemiptera: Aphididae: Eriosomatinae) on Rhus hosts (Anacardiaceae)

Intercontinental biotic disjunctions have been documented and analyzed in numerous Holarctic taxa. Patterns previously synthesized for animals compared to plants suggest that the timing of animal disjunctions are mostly Early Tertiary and were generated by migration and vicariance events occurring in the North Atlantic, while plant disjunctions are mostly Mid-Late Tertiary and imply migration and vicariance over Beringia. Melaphidina aphids (Hemiptera: Aphididae: Fordini) exhibit host-alternating life cycles comprising an obligate seasonal shift between Rhus subgenus Rhus species (Anacardiaceae) and mosses (Bryophyta). Similar to their Rhus hosts, melaphidines are distributed disjunctly between Eastern Asia and Eastern North America. We examined evolutionary relationships within Melaphidina to determine the position of the North American lineage, date its divergence from Asian relatives, and compare these results to a previous historical biogeographic study of Rhus. We sampled nine species and three subspecies representing all six genera of Melaphidina. Data included sequences of mitochondrial cytochrome c oxidase subunits I and II+leucine tRNA, cytochrome b, and nuclear elongation factor 1α genes. Phylogenetic analyses (Bayesian, maximum-likelihood, parsimony) of the combined data (3282bp) supported the monophyly of all genera except Nurudea and Schlechtendalia, due to the position of N. ibofushi. While the exact position of the North American Melaphis was not well resolved, there was high support for a derived position within Asian taxa. The divergence of Melaphis from Asian relatives centered on the Eocene–Oligocene boundary (∼33–35Ma), which coincides with closure of Beringian Land Bridge I. This also corresponded to the Asian–North American disjunction previously estimated for subgenus Rhus spp. We suggest the late-Eocene Bering Land Bridge as the most likely migration route for Melaphis ancestors, as was also hypothesized for North American Rhus ancestors. Results for the Melaphidina disjunction depart from the modal pattern in animal lineages, and present a case where insect and host-plant taxa apparently responded similarly to Tertiary climate change.

Influence of Closure Sequences on the Rigid Frame-Continuous Girder Bridge Closure

Closure sequences of rigid frame-continuous girder bridge are analyzed by calculation to compare girder deflection change, pier horizontal displacement maximum, girder and pier stress value. The results show that the first side span-second side span-mid span closure sequence causes the largest girder vertical displacement and others cause almost the same vertical displacement; side piers pier top horizontal displacement is larger than middle piers whatever the closure sequence is, closure sequences could not change the stress of the girder and pier. The first side span-mid span-second side span closure sequence should be preferred.

The Alignment Control of Large-Span Continuous Beam Bridge Cantilever Construction Method

One long-span bridge adopted the cantilever casting method, which is pre-stressed concrete variable cross-section continuous box girder structure. In the construction process, due to the concrete pouring, hanging basket moving, construction loads, pre-stressed tension, concrete shrinkage and creep, temperature, humidity and many other factors. There will be such problems of cantilever beam segment closed error and the bridge line-type do not coincide in design goals. In this paper, we use the bridge dedicated finite element program MIDAS / Civil procedural for modeling and structural analysis. Analyze the problems of deflection control and pre-camber adjustment of cantilever construction, in order to ensure that the bridge closure smoothly in accordance with the design standards.

Analysis of the Design Method for the Casual Anchor Skeleton at the Closure for PC Continuous Box Girder Bridge

A finite element study was performed to investigate the design method of the casual anchor skeleton at the closure of a PC continuous box girder bridge. Based on a finite element model of a certain four spans PC continuous box girder bridge, we found that the stresses of skeleton calculated with the finite model were 5 percent beyond those with the traditional analytic method. Besides, the tensile stresses increased 19 percent and the compressive ones were 14 percent decreased considered the vertical unbalance temperature and both increased 8 percent for the wind, which were totally ignored in the traditional analytic method. So, the traditional analytic method is inaccurate and unsafe for the casual anchor skeleton design, and the general temperature difference, the vertical unbalance temperature and the wind are better to be considered.

Modal and thermal analysis of Les Arches unstable rock column (Vercors massif, French Alps)

A potentially unstable limestone column (∼1000 m3, Vercors, French Alps) delineated by an open rear fracture was continuously instrumented with two three-component seismic sensors from mid-May 2009 to mid-October 2011. Spectral analysis of seismic noise allowed several resonance frequencies to be determined, ranging from 6 to 21 Hz. The frequency domain decomposition (FDD) technique was applied to the ambient vibrations recorded on the top of the rock column. Three vibration modes were identified at 6, 7.5 and 9 Hz, describing the upper part of corresponding modal shapes. Finite element numerical modelling of the column dynamic response confirmed that the first two modes are bending modes perpendicular and parallel to the fracture, respectively, while the third one corresponds to torsion. Seismic noise monitoring also pointed out that resonance frequencies fluctuate with time, under thermomechanical control. For seasonal cycles, changes in frequency are due to the variations of the bulk elastic properties with temperature. At daily scale, increase in fundamental frequency with temperature has been interpreted as resulting from the rock expansion inducing a closure of the rear fracture rock bridges, hence stiffening the contact between the column and the rock mass. Conversely, the rock contraction induces a fracture opening and a decrease in resonance frequency. In winter, when the temperature drops below 0 ◦C, a dramatic increase in fundamental frequency is observed from 6 Hz to more than 25 Hz, resulting from ice formation in the fracture. During spring, the resonance frequency gradually diminishes with ice melting to reach the value measured before winter.

The Long Road to Recovery: Environmental Health Impacts of Hurricane Sandy

Building contractor John Pierciey stands in the gutted interior of a 1950s-era home in Manasquan, New Jersey. Wallboard, two layers of wood flooring, a layer of felt—all of it had to be ripped out to rid the house of mold caused by Hurricane Sandy’s storm surge. “This is the sixth house I’ve gutted in a week,” Pierciey says. “Every one is different. You don’t know what you’re going to find until you take them apart.” Residents and volunteers keep warm by a fire barrel in the New Dorp Beach neighborhood of Staten Island, 5 November 2012. Power outages persisted through a cold snap that put temperatures in the single digits. So it is with the environmental health impacts of Hurricane Sandy. Every layer of society, every type of building, has felt the impact of the storm, which struck the U.S. East Coast on 29 October 2012. Incidences of death and illness, though small in number compared with some storms, have come in many forms, the effects still unfolding as time goes by.

Experimental Study on Full-Scale Pretensioned Bridge Girder Damaged by Vehicle Impact and Repaired with Fiber-Reinforced Polymer Technology

AbstractA bridge was damaged when a dump truck violated the height clearance limitation on Highway 401 in Ontario, Canada. The collision caused extensive damage to the AASHTO Type-III precast/prestressed bridge girders, which led to the closure of the two-lane bridge. Crack mapping showed extensive torsion-shear cracks between the girder quarter points, horizontal crack at the flange-web junctions, and spalled concrete at point of impact. Preliminary elastic testing on the girder established that the flexural capacity of the girder had not been significantly affected. As such, flexural strengthening was not necessary. Crack patterns and severity, followed by analysis, have shown that the girder is deficient in shear capacity. Therefore, the girder was strengthened for shear throughout its entire length using carbon fiber–reinforced polymer (CFRP) sheets. This paper presents a summary of the design and detailing of the elastic behavior test conducted before repair, the girder repair methodology, and result...

Measurements and prediction of typhoon-induced short-term general scours in intermittent rivers

Most rivers in Taiwan are intermittent rivers. A short-term general scour usually occurs in the river during the rising limb of a flood due to the transitory sediment imbalance and the steep slope gradient. In this study, a severe maximum general scour depth of 4.5 m was measured near the Highway Bridge hydrological station in a gravel-bed reach of the lower Dajia River, which was caused by a flood induced by Typhoon Sinlaku in 2008. This type of short-term general scour is usually very significant and cannot be neglected as it has caused many casualties in Taiwan such as bridge and embankment failures, for example, the Houfeng Bridge failure in the lower Dajia River (Hong et al. in J Hydraul Eng ASCE 138(2):186–199, 2012) and the Shuangyuan Bridge failure in the lower Gaoping River. Based on the collected field data, a general scour formula was developed and gave reasonable predictions. In conjunction with the real-time ultrasonic water level measurements, the formula can be used as a potential tool for the emergency evacuation or bridge closure purposes.

Ergebnisse der operativen Therapie großer Hiatushernien

Hiatus hernias are considered as the most prominent form of diaphragmatic hernias. The passage is defined through the oesophageal hiatus, resulting in a superdiaphragmatic displacement of parts of the stomach or the complete stomach, respectively. In our work we investigated the treatment of partial thoracic stomach with both open and minimally invasive surgical procedures emphasising the view on operating data, the success of the surgery and recurrence rates. Patients with mesh insertion for hernia defect closures were considered separately. 94 Patients were treated in the period from 01.01.2003 to 01.06.2010. The ratio male/female was 2 : 1. The median age was 66 years. All data were prospectively collected by means of surgical protocols and data from the central patient records and analysed retrospectively. The statistical analyses were performed with SPSS 18.0 (SPSS Inc., Chicago, IL, USA). Any existing significances were determined using the T-test. Of the 94 patients, 65 were operated laparoscopically. In the case of nine patients an initial laparoscopic surgery had to be changed to an open procedure. The reasons for switching surgical procedures were splenic bleeding in the case of 2 patients, intestinal injury due to perforation by the trocar in one case and unclear surgical situs in 6 cases. The postoperative complication rate was 24 %. The main reasons were a delayed achievement of passage. The mortality rate was 0 %. The comparison between laparoscopic and open groups showed, by comparable complication and recurrence rates, a shorter recovery time in favour of patients operated on laparoscopically. Additionally it can be stated that a bridge closure with mesh (ePTFE) had no significant influence on the postoperative outcome. Therefore we cannot confirm the postulated poor postoperative results of other groups. In summary, the clear trend in the surgical treatment of hiatus hernias is to minimally invasive surgery. Only for patients with multiple previous operations, who are expected to have strong adhesions, the operation with comparable morbidity and mortality rates can also be planned primarily as open. In this case, however, longer postoperative recovery times must be expected. Large defects can be treated with comparable complication and recurrence rates by mesh insertion (ePTFE).

Deflection and frequency monitoring of the Forth Road Bridge, Scotland, by GPS

The use of carrier phase kinematic GPS (global positioning system) has evolved into a reliable technique to measure both the three-dimensional magnitudes and frequencies of movements of structures. Techniques have been developed that tackle errors caused by multipath, tropospheric delay and issues relating to satellite geometry. GPS-derived movements compare well with data from both design predictions and structural models. Results from field trials carried out on the Forth Road Bridge are presented. This paper brings together key results that outline the procedure as well as a series of new data that indicate other potential applications. GPS data were collected continuously over a period of 46 h at a minimum rate of 10 Hz. During the trials wind speed, wind direction, relative humidity and temperature were also recorded. Frequently there was very heavy traffic flow, and at one point a special load (a 100-t lorry) passed over simultaneously to the heavy daytime flow of traffic. Data from a planned load trial during a brief bridge closure are reported and compared with the limited results available from a finite element model. Measured vibration frequencies are also computed from GPS data and compared with those given in the literature. In addition, results indicating the change in structural characteristics are also presented – in particular changes of mass associated with changes in traffic loading are observed. The results show the performance of GPS as it has developed in recent years, and that it can now reliably be used as a significant part of structural health monitoring schemes, giving both the magnitude of quasi-static deflections in known time periods and hence the frequency of dynamic movements of structures.

Seismic performance of concrete bridges during Canterbury earthquakes

AbstractIn less than six months, the city of Christchurch, New Zealand, experienced two major earthquakes: on 4 September 2010 and 22 February 2011. The former was generated by the rupture of the previously unknown Greendale fault, releasing a magnitude Mw 7.1 earthquake 30–40 km away from the Central Business District (CBD); the latter event, of magnitude Mw 6.2, was less than 10 km from the CBD on an unknown buried fault at the edge of the city. There was widespread damage to the lifelines covering not only Christchurch City but also the closest districts of Selwyn and Waimakariri. The different nature of the fault ruptures and locations of the two events resulted in a variation in damage levels between the earthquakes throughout the region.Teams from various organizations performed inspections on over 800 bridges throughout the affected Canterbury region. No major collapses were registered among concrete bridges and only 20 bridges required closure due to damage caused by the two earthquakes. Owing to the nature of the Canterbury soils, extensive liquefaction and lateral spreading occurred throughout the region. It was this lateral spreading that caused most of the traffic disruption and closure of bridges, due to damage to the abutments and approaches, foundation settlement and rotation.The authors aim to give a detailed overview of the damage assessment and seismic performance of the Canterbury bridges during these two earthquakes, emphasizing unexpected issues that are still not properly detailed in New Zealand and overseas standards.

Eastern Association for the Surgery of Trauma: A Review of the Management of the Open Abdomen—Part 2 “Management of the Open Abdomen”

During the course of the last 30 years, several authors have contributed their clinical experience to the literature in an effort to describe the various management strategies for the appropriate use of the open abdomen technique. There remains a great degree of heterogeneity in the patient population, and the surgical techniques described. The open abdomen technique has been used in both military and civilian trauma and vascular and general surgery emergencies. Given the lack of consistent practice, the Eastern Association for the Surgery of Trauma (EAST) Practice Management Guidelines Committee convened a study group to establish recommendations for the use of open abdomen techniques in both trauma and nontrauma surgery. This has been a major undertaking and has been divided into two parts. The EAST practice management guidelines for the open abdomen part 1 “Damage Control” have been published.1 During the development of the open abdomen part II “Management of the Open Abdomen,” the current literature remains contentious at best, current methods of treatment continue to change rapidly, and patient populations are so heterogeneous that clear recommendations could not be provided. What follows is a thorough review of the current literature for the management of the open abdomen: part 2 “Management of the Open Abdomen” and provides clinical direction regarding the following specific topics.

Bauchdeckenverschluss und Narbenhernienprävention - Was braucht die Chirurgie?

In the light of an incisional hernia incidence of between 10 and 20 % that remains constantly high in spite of modifications of suture materials and suture techniques, intensified scientific efforts aiming at incisional hernia prevention are -required. This article reviews the scientific results dealing with incisional hernia incidence, time of manifestation, risk factors and the influence of suture material and suture technique. A lack of evidence-based data and no current consensus concerning the ideal material and technique to close laparotomies has to be mentioned. To encourage a novel approach to incisional hernia -prevention, the results of experimental studies which demonstrate the negative effects of conventional laparotomy closure on the abdominal wall are discussed. Histology and additionally -laser-fluorescence angiography reveal the weak-en-ing of abdominal wall structures and abdominal wall perfusion after directly suturing the -incisional edges. Additionally, inadequate suture -tension has an influence on collagen quantity and quality in the healing incision. Further investigations with a suture simulator have made clear that surgical sutures vary widely in precision and reproducibility of suture tension when completed only under visual and tactile control. As suture tension dynamics cannot be measured due to the lack of adequate devices, an implantable sensor has been developed that reveals a loss of suture tension of up to 60 % of the initial tension in the first 2 hours after completion of laparotomy closure. These results have led to the development and experimental use of a bridging closure with a tension-banding technique. This technique has almost no influence on abdominal wall per-fusion, leaves the architecture and dynamics of the abdominal wall intact, and results in a favour-able ultra-structural composition of collagen and a mechanically stable laparotomy healing after 15 months. Measures to prevent incisional hernia formation - which is in fact the post-operative complication in surgery most frequently leading to re-operation - require intensified research activities. Success will only be achieved if the development of -unconventional closure techniques is encouraged and the beaten path of suturing the incisional edges is discarded.

Estimating Route Choice and Travel Time Reliability with Field Observations of Bluetooth Probe Vehicles

Route choice is often assessed with either a modeling technique or field observations. Field observations have historically used a variation of license plate matching. The proposed technique assesses route choice and travel time that uses an anonymous Bluetooth media access control (MAC) address sampling technique as a surrogate for license plate matching to assess route choice. The Bluetooth sampling technique was used to evaluate the impact of an unexpected bridge closure in northwest Indiana, including an assessment of the proportion of vehicles using each of four alternate routes. The Bluetooth technology also provided a means to collect travel time data for each alternate route; these observed travel times were also compared with travel time estimates obtained by route classification and link distance. In general, the route choice behavior was consistent with observed travel time estimates. The Bluetooth sampling technique is cost-effective to deploy, and although results are approximate, direct measurement of travel times and route choice is useful for public agencies to assess mobility and travel time reliability along alternate routes.