A műemlékek sokszínűsége (A 28. Egri Nyári Egyetem előadásai 1998 Eger, 1998)

Előadások / Presentations - TÓTH Ernő: Conserving our bridges and protecting

also merit preservation. Győző Mihailich's Bega bridge in Temesvár (Timisoara), along with several others built around the same time demonstrate the boldness and distinction of these engineers. The valley bridge in Veszprém is the product of Róbert Folly's thorough aesthetic studies. The Tihany overpass is a tribute to László Lipták's innovative approach, and most of the monolithic reinforced concrete bridges on the M7 are worthy, interesting designs. The arch bridge at Mecseknádasd designed by Elemér Bölcskei is bigger and more spectacular than that at Veszprém, and it is a pity that the vegetation prevents there being a really good view of it. Of the more recent steel bridges, the Elizabeth Bridge in Budapest cannot go unmentioned, but the Tisza bridge in the centre of Szeged and many other river bridges are also major works of Hungarian bridge-building. CARE OF BRIDGES Bridges, even more so than buildings, are highly exposed to the weather (including floods), environmental pollution (including salt) and the increasingly aggressive effects of traffic. Road operators have a very difficult tasks maintaining older bridges which were not built for modern traffic. Wooden bridges are increasingly confined to local-government and forestry roads, and protecting them against rot and insect damage is an onerous task. Maintenance of steel and reinforced concrete bridges is also difficult and costly (approximately 1.5 per cent of the value of the bridge must be spent annually on upkeep). Most arch bridges are made of stone, and even without insulation are not in bad condition, although there are unfortunate exceptions. The condition of brick arches is less good, and demand continuous repair and good drainage. Arch bridges can withstand rather greater loads than was previously thought. Flat, irregularlyshaped bridges built with little in-fill need to be strengthened, which can be accomplished by a reinforced concrete arch built on to the upper surface of the arch or by a spanning slab. It is the width of these bridges which is a greater problem. Bridges built in the 18th and 19th century are generally not wide enough to carry two-way traffic, and so before the Second World War the parapets of many bridges were removed, or they were widened by with reinforced-concrete slabs. The best approach is to widen them with an arch of the same shape as the original. The bridge across the river Gombás in Vác, one of the country's oldest and most valuable bridges, ornamented with statues, was widened in this way without any aesthetic loss. Arches built of good stone can in principle last indefinitely, and although steel and reinforced-concrete bridges are rather more vulnerable, studies have found that fatigue in steel does not always render it necessary to rebuild 80-100 year-old bridges, and there are examples of well-preserved reinforced concrete bridges. Sometimes it is not possible to save an old bridge. In such cases there is sometimes the possibility of preserving some parts of them either in place or in an outdoor museum. Relics of many old bridges from around the country are held in the Transport Museum, and nowadays in the Kiskőrös Road Transport Collection. Exhibition of parts of an old bridge, like at the Árpád bridge in Budapest, or at Tahitótfalu, is of great educational value. An example I consider to be uniquely effective is the „bridge monument" at Kaposvár, which gives a clear insight, even for lay people, into a bridge structure nowadays not found anywhere.