result of social protests against other alternative solutions. A large span bridge thus became necessary to allow for the unconstrained future modernization of Rę dzin water stage of fall and two water locks.The bridge consists of three substructures ( Fig. 2): -E1 southern fl yover: 610-m long, 11 span continuous beam (box girders) made of prestressed concrete, span lengths 40 + 2 × 52 + 56 + 6 × 60 + 50 m; -M2 cable-stayed main bridge: 612-m long, span lengths 50 + 2 × 256 + 50 m, with two separate superstructures made of prestressed concrete, suspended to a single 122-m high pylon;-E3 northern fl yover: 520-m long, nine span continuous beam (box girders), made of prestressed concrete, span lengths 50 + 7 × 60 + 50 m.The superstructure of the main bridge, presented in Fig. 3, consists of two box girders made of prestressed concrete class C50/60 (one for each carriageway of the motorway), suspended to an H-shaped concrete pylon (concrete class C50/60). Inclined side walls of the girders were made of reinforced concrete precast panels. AbstractThis paper describes the largest structure along the motorway ring road of Wrocław (Poland)-a cable-stayed bridge over the Odra River near Rę dzin barrage. The river flows there in its main bed, while inland navigation uses additional water channels. Pylon of the new bridge is situated on an island located between the river and the channels. The structure is 1742 m long and consists of two multi-span flyovers and a 612-m-long cable-stayed bridge with separate decks suspended to one 122-m-high pylon. The superstructure consists of two prestressed concrete box girders, one for each carriageway of the highway. The decks of the main bridge are suspended to a reinforced concrete pylon by 80 pairs of stay cables. The bridge with a deck area of approximately 65 000 m 2 was constructed within 36 months.

The Centennial Hall, a reinforced concrete structure with an auditorium for 10 000 people, was opened in Wrocław, Poland (then Breslau, Germany) Short historical outline of massive domesThe most famous building with a roof constructed as a coffered concrete dome is the 2000-year-old Pantheon in Rome, commissioned by Marcus Agrippa in 27 BC and rebuilt by Emperor Hadrian in about 126 AD [1]. During its history, the building had various functions and was eventually turned into a church. It is a great structure with a central opening (oculus) at the crown and a lower ring 43.3 m in diameter. The thickness of the dome varies from 6.4 m at its base to 1.2 m at the level of the oculus [2]. The stresses in the dome were reduced by using lightweight aggregate, e.g. pieces of pumice in higher layers, which decreased the density [3]. This reduced the weight of the roof, as did the coffered structure of the dome ( (Fig. 2), erected under Justinian between AD 532 and 537, is one of the greatest achievements of Byzantine culture and has undergone a turbulent history, also during its construction. In May 558, following the earthquakes of August 553 and December 557, parts of the central dome and its supporting structure collapsed [5]. Between 558 and 562 a new modified design was introduced, resulting in the dome we see today.The next large dome structures were built in Europe during the Renaissance [7]; Florence Cathedral (the largest dome since antiquity, with a diameter of 44 m) and St. Peter's Basilica in Rome (on the left in Fig. 3), which has a dome with an inside diameter of 42.7 m [8]. This is a double shell structure made of bricks and travertine blocks held together with lime mortar, stiffened by 16 ribs and supported by a cylindrical structure stabilized by 16 buttresses [8]. During the construction of the dome, carried out in 1589-1592 by Giacomo della Porta, three iron chains were built into the internal shell, and in 1590 two additional hoops were added at the base of the lantern [9].

The road and railway infrastructure in Poland has been intensively developed and modernized for the last years. Around 300 new bridges are built annually. Among the new structures, there is a group of modern extradosed bridges. This paper presents examples of short-, medium-, and long-span extradosed bridges designed and built in recent years in Poland. The following structures are described in details: (1) the first Polish extradosed bridge; (2) two-span landmark viaduct over motorway; (3) multispan curved motorway bridge; (4) the longest Polish extradosed bridge; (5) tramway extradosed bridge; and (6) conceptual designs. The paper is concluded with geometrical parameters characterizing presented structures. The parameters are compared with values obtained for cable-stayed bridges and extradosed bridges built worldwide.

The road infrastructure in Poland has been intensively developed and modernised over the last years. During the past decade more than 2500 new bridges have been built along the main roads and motorways, including several large multi-span structures with a length of more than 500 m. This paper describes the design and construction of the cable-stayed bridge in Wrocław and the extradosed bridge in Kwidzyn. Both structures are the largest concrete bridges built in Poland and are also among world leaders in their class. They can presently be considered to be the greatest achievements of Polish civil engineering. The Rędziński Bridge over the Odra River in Wrocław is a 612 m long cable-stayed bridge with two spans of 256 m suspended to a single 122 m high concrete pylon. The bridge in Kwidzyn is a 808 m long six-span extradosed bridge with two longest spans of 204 m. The paper concludes with a brief comparison of both structures including consumption of materials and costs.