A cable-stayed bridge with a total length of 810 m is being constructed under difficult conditions in a mountainous area at kilometer 25 of the combined (rail and motor) road from Adler to the mountain resort Alpika-Service. It will be the first cable-stayed traffic bridge constructed in southern Russia.

As per the design, the bridge will be located at the exit from the third and longest tunnel complex of the combined road and will cross the Mzymta River, which makes a compound bend in the area of Kepsha settlement.

“The decision to build this bridge was made after studying the geological features of a rocky area near the northern portal of Tunnel Complex No. 3”, Vladimir Prostokvashin, the Head of the STROY-TREST division of the SK MOST group of companies, explained. “The river valley narrows sharply here, and the rocks are close to one another. Building a bridge with long spans is required in order to avoid landslides on this section and cross the river with minimum damage to the landscape. In this case, the length of the main suspended span will be 300 m with pylon height of 90 meters.”

A cable-stayed bridge is a more complex engineering structure in comparison with beam bridges. It seems to “hang” in the air, supported by only two pylons connected to the deck by heavy-duty steel cable stays. Cable-stayed bridges are constructed when it is required to cross large distances and avoid installation of additional piers.

Progress of all work at kilometer 25 of the Adler – Alpika-Service road will be determined by the geological conditions and design features of the cable-stayed bridge. In the specialists’ opinion, geological surveys in this area should be carried out during the whole construction period, since soils in the Caucasus foothills are quite nonhomogeneous. Since the bridge is being constructed at the northern portal of Tunnel Complex No. 3, the tunnel boring crew will not only have to carry out near-portal work, but also arrange surface exit of a tunnel boring machine with a diameter of 13 meters, which is now being used for driving the traffic tunnel. Builders will have to place the tunnel boring and road-building machinery on a small piece of land, since the rocks come almost up to the river bank in the river valley.

“We are now close to completing drilling operations for the foundation of pylon No. 2”, Eugene Yakovlev, STROY-TREST’ Operations Manager, said. “A short time later we will proceed to bank protection and installation of a cutoff wall in the Mzymta River bed.”

STROY-TREST expects to complete construction of the cable-stayed bridge as early as the end of 2011.

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