Bridges and viaducts

Third Guards Brigade 'Kune' Bridge

The A5 Highway on the Beli Manastir - Osijek - Svilaj (r. Sava) route, a component of the C5 branch of the European network carrying the following mark: E73, which is located on the west side of the city of Osijek, near Petrijevci, was supposed to bridge the Drava River and its inundation area. So as not to create a barrier to the future expansion of Osijek, as well as to the possibility of building a hydroelectric power plant on the r. Drava, as a result of a process of choosing a crossing project solution, a bridge with a total length of 2,485 (2,507) m and access viaducts was created. What is interesting is that the Drežnik viaduct near Karlovac is the same length as the "Kune" Bridge, so these two objects share the first place in Croatia with regards to their size. By comparison, the Pelješac Bridge is 2,440 m long.

The bridge consists of three parts: a) the Baranja side access road over the inundation (length: 1,074.5 m, 28 + 29 x 35 + 31.5 m), b) the bridge crossing the Drava river (length: 420 m, 100 + 220 + 100 m), and c) the Osijek side access road (length: 990.5 m, 24.5 + 28 + 26 x 35 + 28 m). Both access roads were built as two separate viaducts, one for each direction. They have span structures made of prestressed T-section concrete supports (height: 1.85 m), with six of them in cross-section, and are connected with a 25 cm thick pavement slab, supported with two Φ 1.8 m columns lying over the overhead beams. The foundations are based on drilled pylons (Φ: 1.5 m). The span structures of both access roads are divided into six expansion units. The center of the object is the part that bridges the Drava, which has been designed with a suspended span construction, with spans of 100 m + 220 m + 100 m, and 75 m tall type A pylons. The pylons are made of reinforced concrete, with a 4 x 5 m (at the top: 3.5 x 6 m) section of arms. From pylons on both sides, a row of 10 diagonal tension rods composed of high-quality steel ropes descends and stretches across. The tension rods are protected by ribbed HDPE pipes. The pylon arms are based on two batches of 25 drilled pylons with a 1.5 m diameter. The span construction of this part, which consists of a three-chamber steel box girder with a cross-section of approx. 12 x 2.8 m, and 8.3 m long prominent consoles supported by steel beams, is supported by the tension rods described, which transmit force to the pylons. The tension rods connect to the span structure in the central chamber of the structure. The total width of the span structure in this part (420 m) is 28.6 m.

The authors of the Concept Project are Peter Sesar, Ph.D. (Civil Engineer) and Damir Tkalčić, M. Sc., while the author of the Main Project is Damir Tkalčić, M.Sc. The construction works were performed by a business association consisting of the following companies: Viadukt d.d., Zagreb; Osijek Koteks d.d., Osijek; Konstruktor Inženjering d.d. and Skladgradnja grup d.d., (both from Split), as well as Hidroelektra - Niskogradnja d.d., Zagreb. The labor contract price of the project in 2009 was approx. 950 million HRK. 

Mirna Viaduct

The A9 highway (Istrian Y highway) connects the city of Pula and famous tourist centers on the west coast of Istria via the Plovanija and Kaštel border crossings with Ljubljana and Trieste, and further on with various cities of Western Europe. On the Nova Vas - Višnjan subsection of this 76.8 km long highway, the floodplain of the Mirna River is bridged by a magnificent viaduct (bridge), with a total length of 1,378 m. In addition to the Mirna River, under the viaducts, there are two smaller canals and a road. The object was built on the route of the right carriageway of the highway. The viaduct for the left carriageway will be built within the scope of the complete project of the A9 highway, which will help this highway reach its full profile. Near the viaduct, the Mirna River meets the sea, and the city of Novigrad is located. The valley below the viaduct offers valuable agricultural crops.

The span construction of the viaduct consists of two solid steel walls with tin carriers of constant height (2.75 m) at a distance of 5.50 m. The carriers are connected by steel cross-members and a 25 cm thick reinforced concrete pavement slab. The static system is a continuous carrier stretching over 22 spans, with a total length of 1,353.86 m. The sizes of the spans are as follows: 51.1 + 15 x 66.5 + 70.1 + 2 x 50.1 + 63.1 + 42.6 + 30.6 m.

The total width of the object is 10.10 m, and it consists of two traffic lanes, each 3.5 m wide, and two protective belts, each 1.0 m wide, as well as protective fence areas, each 0.5 m wide. The ground plan of the viaduct follows a curve (R = 4,005 m). The height of its columns ranges from 13.5 to 40.0 m. Its H section is 4.5 x 3.8 (2.5) m wide and made of reinforced B35 concrete. The abutments, as well as the lower columns, are supported by a rock, while the higher columns, due to weak load-bearing soil, are based on steel 61 m long pylons, connected with reinforced concrete, and a 2.0 m thick headboard. When it comes to the quantity of materials used for the construction of the viaduct, it is as follows: B35 concrete –11,190 m3; BSt 500S reinforcing steel - 1,831 tons; structural steel of span construction St 52-3 – 2,720 tons. Investor: BINA-Istra; Designer: Zlatko Šavor, Ph.D., Master of Civil Engineering. Contractor: Bouygues France. Zvonimir Zdenko Šimunjak, Master of Civil Engineering

Stamp Issue: 2023.03.20