1 2 3 4 5 6 7 The Metrolink phase 3 project in Manchester, UK, has created around 60 km of new tram lines and has incorporated over 380 structures including 160 bridges and tunnels. Nearly 80 bridges were refurbished, repaired or strengthened to provide a low-maintenance system with a minimum 50-year structural design life. The new tram lines have been built on new dedicated alignments and on former railway corridors, reusing existing structures with an age of up to 140 years. Various contractual and technical approaches were taken to address the risk due to structure condition, including risk-sharing arrangements and phased scope determination. Particular issues encountered by the project include: limited information on structure condition; corrosion of metallic structures; scope risk; strategy for repair versus replacement; vehicle incursion risk; determining appropriate specifications; retention of cast-iron structures and modifications to parapets due to electrification. The conclusions include lessons learned for projects dealing with the renewal and upgrade of legacy structures in an affordable manner. Bridge Engineering Volume 167 Issue BE3 Refurbishment of structures on the Manchester Metrolink phase 3 Stacy, Burr, Jones et al.
Welcome to this themed issue of Bridge Engineering on the subject of assessing the capacity of existing bridge structures.Many parts of the world continue to provide opportunities for major new bridge construction. These include the massive investment in infrastructure in China and the Far East; the urban metro schemes in India and the Middle East; and the high-speed rail lines in Europe and the USA.However, many countries now have extensive stocks of mature bridge assets. A typical example is provided by the paper in this issue by McKoy (2016) on London Underground, which has a stock of approximately 8000 bridges and other assets, of which nearly half were constructed before 1900.Assessment is a key tool for the management of existing bridges. Assessments may be undertaken to check that bridges are safe under the loads they are already experiencing. In addition, increasing traffic capacities and loading often require the evaluation of the carrying capacity of existing structures. Changes to structures, such as modifications or external damage or deterioration, may need to be assessed.Bridge assessment, although a challenging subject, can also be a rich field that offers opportunities for research, innovation and the development of technical expertise. The rewards can also be significant: analytical approaches are generally less costly than structural strengthening, so there can be many benefits in progressing sophisticated investigation and analysis methods to justify the strength of structures.This issue of Bridge Engineering includes five papers from across this full range of endeavours. Papers include a discussion of an asset owner's assessment programme spanning three decades; a methodology for evaluating the potential benefit of installing structural monitoring systems; techniques for controlling proof test loading using acoustic emission; development and calibration of a finite-element approach to service-level assessment of masonry arch bridges; and a case study of a project to assess a 620m-long steel-composite box girder viaduct by deploying Eurocode methods. Olaszek et al. (2016) consider the on-site assessment of bridges supported by acoustic emission. In situ tests show that sometimes bridges have a reserve strength that is not accounted for in design codes of standard assessment methods, since the codes may conservatively neglect contributory mechanisms. Full-scale load testing can demonstrate these reserves of strength. However, proof load testing up to the design load may have risks of inducing cracking or damage in the structure if it is not properly performed and controlled, owing to the high level of load in the bridge.Acoustic emission has been identified as a useful technique to stop the load increase before any damage can be inflicted on the bridge. The paper presents tests on a three-span bridge at Barcza, Poland, and shows that monitoring with acoustic emission sensors made it possible to evaluate the cracking limits of the concrete members and stop the load increase prior to the onset of...
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Future Ready is a framework developed by WSP to help our designs respond to the rapidly changing world. Future Ready helps our projects to be ready for new global challenges by engaging clients and inspiring designs for the future. By understanding future trends and technologies, it can improve project outcomes through good conceptual design. We present three case studies to explain how we consider future trends, the process followed and the benefits of the Future Ready approach. The Waterloo Bridge project responded to trends in technology by adjusting the project scope to trial advanced satellite monitoring techniques applied to bridge movements. In light of trends for healthy transport, the conceptual design of Bromley Heath viaduct refurbishment enhanced the use of an existing structure for non-motorised users. The solution developed for Hammersmith Flyover considered trends in resources and novel materials by deploying Ultra High Performance Concrete on a high profile application.
Welcome to this latest general issue of the Bridge Engineering journal. As a member of the editorial panel and as a practising consultant engineer, it is gratifying that the content of this journal is representative of current bridge engineering practice and research, the issues facing bridge owners and designers and the innovations being developed by engineers and researchers to overcome these challenges.In this issue we present a range of papers linked by this common theme of addressing current issues. The papers include innovation and development of the structural forms of the arch and the integral bridge, and application of the latest digital imaging technology to improve our understanding of the behaviour of existing structures. Other papers consider current box-girder erection techniques, the management of deteriorating structures and understanding residual fatigue life. These issues are relevant wherever bridges are built and maintained, and contributions to this journal have come from across the world.The drive to reduce maintenance costs has led integral bridges to become a preferred form of construction since these can eliminate bearings and expansion joints. However, the cyclic thermal movement of the deck generates enhanced lateral earth pressures behind the abutments which can have a dominant effect on the sizing of bridge components. Davies et al. (2014) examine three contrasting backfill options for the design of an overbridge and show that an expanded polystyrene block option offered significant material savings in the substructure. The authors compare load effects generated by the different backfill options and find that expanded polystyrene offers a bending moment of around one-fifth of traditional granular fill. The carbon footprint is calculated for the options and both expanded polystyrene and expanded clay backfills are shown to have lower carbon footprints than granular fill for this example.Whilst the design of new structures can be optimised, bridge owners and engineers must also attempt to make best use of the stock of existing structures. Pipinato et al. (2014) consider the fatigue performance of riveted metal structures. They present a fatigue assessment of a common type of short-span railway bridge. Finite element models of the riveted details are used under static and dynamic analyses to investigate the fatigue damage to critical areas and estimate the residual fatigue life of the structure.Analysis and assessment of existing structures typically requires a good understanding of the condition and behaviour of the structure. Traditionally this understanding has been gained by 'taking a good look'. McCormick et al. (2014) consider the capability of optical imaging technology to update this approach and provide reliable and precise data. Digital cameras are used to capture images of structures and the technique of digital image correlation is used to calculate movements of the structure. The output of the optical technique is verified for three case study structures by comparison with ...
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