Hidak Bács-Kiskun megyében (1999)

Összefoglalás (dr. Tóth Ernő)

SUMMARY County Bacs-Kiskun is the largest Hungarian county. Its area was determined in 1950. It is limited by two major rivers and several canals of various size necessitating to build bridges. In the Arpad age (A.D. 10th centrury), its road network was rather scarce. Later the Danube-ferries, the road junction in Kecskemet, the road between Buda and Szeged, then from the 20th century on, the transverse roads (Baja-Kiskunfelegyhaza, Csongrad-Gyula, Dunafoldvar-Kecskemet-Szolnok, as well as Tiszaug-Bekescsaba routes) and their river bridges increased the traffic significance of the county. In the 16-17th centuries, entrance (lifting) bridges of fortresses through the castle ditches were timber bridges. The pontoon bridge by Kalocsa was famous. The documents of bridge construction remained from the 18th century on. They say that stone bridges were built in Kecskemet in 1747 and 1755. In 1783, already 33 bridges were listed in the town "without rivers". During the first military survey (1785), surprisingly high number of bridges were at the border of various settlements (e.g. 11 in Szabadszallas, 8 in Kalocsa). In Kiskunfelegyhaza, arch-bridges were built in 1772 and 1856. In

r Kalocsa, the flood in 1862 swept the five-span stone bridge away. In the first part of 19th century, the most important arch-bridges in the county were: the still existing one by Dunatetetlen and the famous Voros-bridge in Baja which was swept by the flood in 1862 away. The construction of reinforced concrete bridges started in Solt (first in the whole country) by the building of a Monier-system bridge in 1889, then in 1893, Mr Robert Wiinsch "cement technician" constructed a two-span (9 + 9 m) reinforced concrete arch-bridge of Melan-system. Together with the construction of railway lines, several new bridges were built after 1853 which of them the Danube-bridge by Baja completed in 1909 was of country-wide importance. It was the first permament bridge through Danube below Budapest. The bridge has had a mixed traffic from 1935 on. The river bed spans are 100-100 m, while those in the river flats 50-50 m. The bridge was built by the Hungarian Royal State Iron and Steel Factory, similarly as the rest of the large river bridges. The construction of reinforced concrete bridges of Hennebique system came into usage by the activity of dr. Szilard Zielinski who planned several bridges in the county through Danube-valley main canal and other streams. From 1927 on, characteristic bridges were built according to the design of Dr. Gyozo Mihailich through the upper part of the canal mentioned which crossed the whole county. The great period of the construction of steeel bridges was the one between 1927 and 1930 when the by then missing river bridges on the transversal roads were built by Tiszaug and Dunafoldvar. The one by Tiszaug is of traditional design using up-todate carbon-steel, while the Dunafoldvar-bridge designed by dr Janos Kossalka was the first severalspan, continuous Danube-bridge of truss main girder using silicon steel. Both bridges have been used later also by railway traffic. Of several significant reinforced concrete bridges, the railway underbridge in Kecskemet designed by Robert Folly should be mentioned which had a closed reinforced concrete frame of 110 m length. In the autumn 1944, 27 bridges of the county including all the three river ones and the connecting river bed bridges were destroyed due to the war. The reconstruction was rather abrupt: in 1947, the Tisza-bridge by Tiszaug was rebuilt partly utilizing the lifted remains. While the Danubebridges by Baja and Dunafoldvar were reconstructed totally using completely new continuous truss superstructure in 1950 and 1951. It was a hard task during the reconstruction to remove the bridge remains and to maintain the traffic provisionally in Dunafoldvar, Kalocsa and Baja. Also pontoon-bridges of 30-40 m span were built replacing the blown-up bridges of Ferenc-canal. When reconstructing minor roads, several technical novelties were applied, e.g. two Bordcz-system (Hungarian) post-tensioned bridges, the fifth aluminium bridge in the world in 1950, as well as two precast Hoyer-system prestressed bridge close to Kalocsa in 1953. From 1959 on, precast minor bridges with reversed T-girders have been built. Using precast (EHGT) girders appropriate for spans over 10 m, a 4-span bridge was built by Kecskemet in 1974, while in 1982 a 14-span one in Kecskemet and in 1987 a 3-span bridge above a railway line in Kiskunhalas were constructed. In 1989-90 the Danube-bridge by Baja was wide141