Re-establishing the Functionality of Older Bridges: Two Case Studies, Italy
|Médium:||article de revue|
|Publié dans:||Structural Engineering International, novembre 2008, n. 4, v. 18|
For historical reasons, centuries of development in the Italian region have led to a multitude of flourishing but small urban centres. In this context, it is obvious that communication in the form of roads, canals and rivers have been of fundamental importance to the culture and lifestyle of the region. The continuous change that these centres of habitation have seen from the viewpoint of economic, social and urban growth has made the region's communication system even more complex, forcing infrastructure to adapt to a variation in demand on a regular basis. It is quite understandable that in such a context, bridge building has been a frequent stimulus to engineering genius. No wonder then that, apart from some examples of large-scale engineering, the region can also boast an extremely large number of minor river management and bridge works all over the region, characterised by an inventiveness engendered by incredibly varied and sometimes quite unusual requirements. On top of the obvious functional requirements, in many cases, the physical characteristics of the surroundings and the region in general played a major role in conditioning the shape and form of the finished work. The limitations they dictated, choices they forced and environmental conditions they imposed combined to create a modus operandi that over time led to a characteristic style of public works, of which the bridge is the noblest form. The period in which we ourselves are living is equally affected by perpetual change: new safety requirements have emerged together with new means of transport, and new road layouts are requiring the functional adaptation of works designed and constructed to satisfy needs that have long been superseded. If we are to respect tradition, our approach to the modernisation of existing works must be based on a firm understanding of the needs and conditions that led to their construction in the first place. Unfortunately, in the name of modernisation, in recent decades many projects have been little more than acts of vandalism, irremediably destroying the heritage that ancient works could have preserved for future generations. The attitude behind these interventions was not only lacking in respect for the past and for the value of tradition but also ignorant of the factors driving change in the landscape of the locality involved. Nevertheless, exceptions to this rule, in the form of works performed under the guidance of heritage conservation bodies, are slowly bringing about a change of heart, so much so that nowadays modernisation projects based on a thorough understanding of the local area and its history are becoming increasingly widespread. The inability of bridges to fulfill their original purpose has become increasingly manifest in recent years, amplified by an increase in through traffic in addition to local traffic. The speed of such traffic has also impacted negatively on road safety and led to an increase in the number of accidents. On top of this, the cyclists and pedestrians who use older bridges do so not only without specific protective structures in place but often without the most elementary guarantees of safety. This article examines two cases of modernisation of older main road bridges achieved by the construction of cyclist and pedestrian bridges alongside.
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