The vast majority of our bridges are unremarkable structures which largely go unnoticed by the general public. Movable bridges, however, are unique structures which often interrupt the user's journey, particularly in the case of pedestrians and motorists, giving them the opportunity to pause and consider the ingenuity of the engineering involved. This themed issue of Bridge Engineering is dedicated to such structures.
One particularly pleasing aspect of this issue is the number of overseas papers that have been received. In addition to those from the UK and Ireland, we have papers describing projects in New Zealand, Poland, Sweden, Norway and the USA, making this a truly international issue. These contributions cover road, rail and pedestrian structures in a variety of forms and materials.
In his paper on Te Wero Bridge, Tindall (2011) describes the design of a structure with a unique appearance and unusual articulation, which will undoubtedly become a landmark in Auckland when constructed. One of the key issues in the design of a moving structure is the interface between the structural and mechanical design and, as structural engineers, it is particularly interesting to have the design process presented from a mechanical engineer's perspective by Thorogood (2011) in paper number two.
In paper number three, Hołowaty (2011) describes a rolling leaf bascule bridge which is the only movable railway bridge remaining in service in Poland. It is interesting to note that although this bridge is soon to be decommissioned, it is to be moved and preserved due to its historic value. This is followed by a paper on a modern railway bridge – a vertical lift bridge over the Södertälje Canal near Stockholm. In their paper, Thulstrup et al. (2011) highlight many interesting aspects of its design and construction. Perhaps the most iconic bridge built in Ireland in recent years is the Samuel Becket Bridge in Dublin, and the design and construction of this are described by Cutter et al. in paper number five.
Following this, Catbas et al. (2011) describe typical maintenance issues that arise in the many twin leaf bascule bridges within the Florida bridge stock. They go on to discuss the process of simulating the effect of damage to the span locks and monitoring the condition of these critical elements.
The River Nidelva crossing in Trondheim is the subject of the penultimate paper in which Andersen and Jensen (2011) describe the key design issues for this bridge and how many of the structural and mechanical features have been developed to accord with the architectural requirements. The use of traditional materials and manufacturing methods for the replacement of two timber footbridges at Worcester is described by Ledsham et al. (2011) in the final paper. The material aspect of this paper presents an interesting contrast to that in the opening paper by Tindall.
It has been a particular pleasure to act as guest editor of this themed issue and I would like to thank all the authors who have taken the time and effort to produce the published papers. I would also like to thank those authors who submitted papers that did not complete the review process before the publication deadline. I look forward to seeing these published in regular issues of Bridge Engineering in the near future.
Finally, there are many issues in each of the papers which I am sure are worthy of further debate and I would encourage all readers to take up their pens and participate in the written discussion which I am sure will ensue.
