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

Bridges and viaducts

VIADUKT “MODRUŠ 1” ON HIGHWAY A1 (ZAGREB- SPLIT-DUBROVNIK)

Viaduct „Modruš1“ is the first and the longest in the row of three viaducts of the same name at the road section Ogulin- Brinje of the Highway A1 Zagreb-Split- Dubrovnik, at approach to the tunnel Mala Kapela. The object is situated near the settlement and the ruin of the old town of Modruš which once was also the seat of the Modruška County and can be seen from the right side when driving toward Brinje. The viaduct bridges a deep valley at the height up to 50 m from the lowest point of the valley and has a total length of 516 m and a total width of 31.5 m, enabling thus in standard profile the traffic on highway in both driving directions. Due to that many drivers even do not notice that they have crossed over a remarkable road construction building. In order to get an impression of the size of this viaduct one should exit to a parallel state road D23. The construction actually consists of two parallel, almost identical viaducts each serving one driving direction, which are transversally interconnected for the purpose of checking and maintenance. The levelling line of the viaduct is ascending 4.8% toward the tunnel Mala Kapela. The viaduct consists of 13 sections with centre-to-centre distances of the props (pillars): 38+11x40+38m = 516m. Particular construction spans consist of four prestressed ferroconcrete pillars with coffer cross-section, 2.2 m high and 37 m long, interconnected with a roadway slab. Particular span constructions lean on beam heads of pillars, by means of separate bearings.
The lower structure of the viaduct consists of abutments and pillars based on laminated ferroconcrete foundations, in consideration of rocky basic grounds. The foundations of pillars are 10.0x8.0x2.0 m. The abutments with parallel wings are based in the similar way. The pillars of the viaduct are hollow, of outer cross-section of 2.4 x5.4 m and with the wall thickness of 0.3 m. Used materials are ferroconcrete and prestressed concrete.
The project of the viaduct was made by IGH-Institute for Concrete and Masonry Structures, the designers were Gordana Trogrlić-Uzelac, Stjepan Kralj and Dr. Sc. Petar Sesar. It was built by the company Bechtel-Enka with participation of Croatian companies. The viaduct was opened for traffic in 2005 on the occasion of opening of the A1 Zagreb- Split Highway.

BRIDGE “KRKA” ON HIGHWAY A1 (ZAGREB-SPLIT-DUBROVNIK)

The River Krka, a jewel among rivers of the Adriatic drainage area, probably the most beautiful and attractive among them and well known for its waterfalls, was bridged when the A1 Highway was built, at a point few kilometres downstream from the town of Skradin by an impressive arch bridge. The bridge is located between the nods Skradin and Šibenik, and immediately behind it there is a rest area with a restaurant and viewpoint, from where the view of the bridge and the town of Skradin can be enjoyed. Especially attractive is the view at the bridge for yachtsmen heading to Skradin. The total length of the bridge is 391 m, the width is 22.5 m and it rises 66 meters above the sea level. The main span construction of the bridge over the river Krka is a hollow ferroconcrete arch of 204 m, i.e. 4 m bigger than the bridge of Maslenica (200 m). The cross-section of the arch is 3x10m, with the walls of 0.5 m. As much as 2988 m3 of concrete and 747 t of reinforcement have been built into the bridge, which was constructed according to cantilever principle and with cable support. The structure of the bridge above arch is composed of the grid of steel longitudinal and cross beams with cantilever projections and with rim beams. The longitudinal beams are coffered with cross-section of 0.75x1.7 m and a span of 32 i.e. 28 m. On the described grid a ferroconcrete slab of roadway of 25 cm has been laid. The described structure above arch contains 1700 tonnes of steel, 2172 m3 of concrete and 630 tonnes of reinforcement and it leans on the terrain and the arch of the bridge, by means of pillars reaching up to 55 m. The pillars are of hollow cross-section varying from 3.2x2.5 to 1.8x2.2 m in dependence of their height. Each pillar position has two equal pillars.
It should be pointed out that in the construction of this bridge rational technical solutions have been applied which have made possible – by respecting all prescribed conditions - a savings on the total mass of the object of 35 % in relation to almost identical Maslenica bridge.
The designer of the bridge was Dr. sc .Zlatko Šavor, the supervisor was IGH Zagreb - Dr.sc. Z. Marić, and the bridge was built in the period 2002- 2005 by the company “Konstruktor inženjering Inc.” from Split with the steel part built by the company “Đuro Đaković Ltd.” from Slavonski Brod. The bridge was opened to traffic together with the opening to traffic of the highway Zagreb –Split in 2005.

Stamp Issue: 2015.04.23