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Released: 16. 6. 2010
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The unique arched bridge across the Opárenské Valley in České středohoří is just being completed.
Unfortunately, there is no motorway being brought to it yet. If building permission for the connecting construction isn’t issued, the bridge will have to be ‘canned’ and drivers won’t be able to enjoy it that soon.

It is an exceptional piece of work from both a technical and ecological point of view. The Opárno Bridge on the D8 motorway between Prague and Dresden is 275 m long and 50 m high. It will take the motorway across the valley on two arched independent concrete-steel structures. The construction was commenced two years ago. As it wasn’t permitted to enter the protected landscape area of České středohoří, the construction was designed as overarching the valley without the need of constructional interference. The bridge was constructed with unique technology where everything was built from the top. The concreting of the last panel on a slip centring was done on the 24th May and this completed the bridge floor. “Such large concrete-steel arched bridges aren’t that common in our country and the Opárno Bridge will be the second largest of them. Only the Podolský Bridge across Orlík, which was built 70 years ago, has a bigger 15 m span,“ says professor Ing. Jan Vítek, CSc., from the Faculty of Civil Engineering at the Czech Technical University. But similar arched bridges are quite common overseas.

TWO SYMMETRIC BUILDING SITES

The building site in the protected landscape area was restricted to a very narrow space covering practically only the width of the bridge in the place of the steep hills of the valley. No building activity nor access were allowed in the area beneath the arch. The construction was split into two individual building sites and the teams were working symmetrically opposite each other. This requirement led to the acquiring of two pieces of technological equipment for the construction of the arch and the bridge floor.
Once the foundations and pillars were built, beyond the arch per se, the deck slab was built on both ends of the bridge. Concreting work of the arch was commenced from the springing to the centre at the same time. The three panels of the deck slab supported by pillars beyond the arch formed a connecting rod and allowed for the construction of a temporary pylon which served for suspending the constructed arch. Once the arch was enclosed, part of the suspension could be done away with and the top centring was used for concreting the deck slab above the arch. After the individual operations were completed, the equipment was moved to the other bridge.
The structure of the Opárenský Bridge was reinforced, in co-operation with the contractor of the structure, Metrostav, a. s., division 5, and project office Pontex, s. r. o., by high-strength concrete. This facilitated the construction, material consumption was reduced and the construction’s impact on the environment as well; the structure should also have longer life span. The designed and realised changes led to the saving of a large amount of cement and contributed to energy savings and a reduction in carbon dioxide emissions.

COOLING WITH ICE

Another innovation is water cooling for load bearing structures. When strong concrete hardens, this produces a high setting heat, which has a negative influence on the creation of cracks and the structure’s life span. To restrict this incidence with arches, the armature of each concrete lamella was fixed with tube loops with a closed water circuit that was cooled in a tank with ice.
This helped to reduce the top of the temperature curve by approximately 15 °C. The cooling takes about 30 hours - the highest achieved temperature of 55 °C doesn’t worsen the concrete quality anymore.

BUILDING PERMISSION ‘PER PARTES’

The Lovosice-Řehlovice section includes several unique solutions for penetrating the countryside. The construction is, from a technological and contractual point of view, divided into six individual parts. Out of the total length of 16.4 km, 12.8 km have already got building permission.
Building permission proceedings for another section of 1.75 km are currently in progress. So it is almost a total of 90% of the length of the construction that will get building permission. If the remaining building permissions aren’t obtained, the construction will have to be ‘canned’ at the end of this year.
“We estimate monthly maintenance costs of a ‘canned’ construction at hundreds of thousands of crowns.
But we still have no idea how long the construction should be terminated for. The final ‘canning’ costs can reach millions of crowns,“ says ing.
František Polák, press spokesman for Metrostav, which is a member of the Association D8/0805 SSŽ-MTS for the construction of the D8-0805 motorway Lovosice-Řehlovice.