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The Mirna Bridge is located between the Nova Vas and
The deck structure stretches across 22 spans: + 15 x + + 2 x + + + .
The design of the bridge was initially in spans, but the final layout was imposed by the particular soil conditions and the arrangement of the river bed and canals below the bridge. Since the soil supporting the bridge foundations has exceptionally low load carrying capacity, it was important to reduce weight of the structure as much as possible. Therefore, the design employs two weight-reducing elements: longitudinal steel girders and piers with cap beams at varying heights. The latter reduces volume of concrete used for construction of the piers thereby reducing weight of the structure while giving the bridge a curved, concave deck.
The design of the pier foundations was further affected by the fact that the valley is a high quality agricultural area that had to be preserved as much as possible. The height of the reinforced concrete piers ranges from to and each of the piers is topped by a cap beam. The piers comprise an I-cross section with the webs aligned with the bridge axis. Peripheral piers (P1, P2, P20, P21) are executed on
Višnjan
Višnjan () is a village and municipality in Istria, Croatia. Višnjan is the site of Višnjan Observatory (an astronomical observatory). The observatory is home of several long-running international summer programs for youth in astronomy, archeo ...
interchanges of the A9 motorway in Istria
Istria ( ; Croatian language, Croatian and Slovene language, Slovene: ; Italian language, Italian and Venetian language, Venetian: ; ; Istro-Romanian language, Istro-Romanian: ; ; ) is the largest peninsula within the Adriatic Sea. Located at th ...
, Croatia
Croatia, officially the Republic of Croatia, is a country in Central Europe, Central and Southeast Europe, on the coast of the Adriatic Sea. It borders Slovenia to the northwest, Hungary to the northeast, Serbia to the east, Bosnia and Herze ...
, spanning the Mirna River and the wide Mirna River valley. It is long and comprises two traffic lanes. The bridge has been open for traffic since June 2005. The bridge is one of the most significant structures on the motorway. The bridge was designed by Zlatko Šavor Zlatko ( sr-Cyrl, Златко, ) is a South Slavic masculine given name. The name is derived from the word ''zlato'' meaning gold with hypocoristic suffix ''-ko'' common in South Slavic languages.
Zlatko is a given name. Notable people with the na ...
.
The A9 route between Umag
Umag (; ; ) is a coastal town in Istria, Croatia.
Its patron saint is Peregrine (martyr), St. Peregrine.
Geography
It is the westernmost town of Croatia, and it includes Bašanija, the westernmost point of Croatia.
Demographics
According to the ...
and Kanfanar
Kanfanar (Italian language, Italian: Canfanaro) is a naselje, settlement and a municipalities of Croatia, municipality in Istria, Croatia.
Kanfanar lies at the Kanfanar interchange, interchange of the Istrian Y motorway A8 (Croatia), A8 and A9 (Cr ...
, where the Mirna Bridge is located, was upgraded to motorway standards in June 2011. However, the works did not include construction of a parallel structure across the Mirna River which would carry the additional carriageway. Expansion of the bridge to a full motorway is planned to start in 2013 and be completed by 2015.
Description
The deck structure stretches across 22 spans: + 15 x + + 2 x + + + .
The design of the bridge was initially in spans, but the final layout was imposed by the particular soil conditions and the arrangement of the river bed and canals below the bridge. Since the soil supporting the bridge foundations has exceptionally low load carrying capacity, it was important to reduce weight of the structure as much as possible. Therefore, the design employs two weight-reducing elements: longitudinal steel girders and piers with cap beams at varying heights. The latter reduces volume of concrete used for construction of the piers thereby reducing weight of the structure while giving the bridge a curved, concave deck.
The design of the pier foundations was further affected by the fact that the valley is a high quality agricultural area that had to be preserved as much as possible. The height of the reinforced concrete piers ranges from to and each of the piers is topped by a cap beam. The piers comprise an I-cross section with the webs aligned with the bridge axis. Peripheral piers (P1, P2, P20, P21) are executed on shallow foundation
A shallow foundation is a type of building foundation that transfers structural load to the earth very near to the surface, rather than to a subsurface layer or a range of depths, as does a deep foundation. Customarily, a shallow foundation is con ...
s, while the remaining piers are executed on driven piles. The superstructure consists of two longitudinal prefabricated girders of constant depth set apart made composite with the deck slab and cross-girders. Structurally, the superstructure is a long continuous girder across 22 spans, tracing a horizontal and a vertical curve. The cross section of the superstructure consists of two solid I-section steel girders of constant depth.
Traffic volume
Traffic is regularly counted and reported byBINA Istra
BINA Istra is a Croatian joint stock company founded in 1995 to facilitate construction and subsequent management of an Istrian Y motorway, consisting of the A8 motorway and the A9 motorway. On September 21, 1995, BINA Istra was granted concessi ...
, the operator of the bridge and the A9 motorway where the bridge is located, and published by Hrvatske ceste
Hrvatske ceste (lit. ''Croatian roads'') is a Croatian state-owned company pursuant to provisions of the Croatian Public Roads Act ( enacted by the Parliament of the Republic of Croatia.
The tasks of the company are defined by the Public Roads A ...
. Substantial variations between annual (AADT
Annual average daily traffic (AADT) is a measure used primarily in transportation planning, transportation engineering and retail location selection. Traditionally, it is the total volume of vehicle traffic of a highway or road for a year divided ...
) and summer (ASDT) traffic volumes are attributed to the fact that the bridge carries much tourist traffic to the Istria
Istria ( ; Croatian language, Croatian and Slovene language, Slovene: ; Italian language, Italian and Venetian language, Venetian: ; ; Istro-Romanian language, Istro-Romanian: ; ; ) is the largest peninsula within the Adriatic Sea. Located at th ...
n Adriatic
The Adriatic Sea () is a body of water separating the Italian Peninsula from the Balkans, Balkan Peninsula. The Adriatic is the northernmost arm of the Mediterranean Sea, extending from the Strait of Otranto (where it connects to the Ionian Se ...
resorts. The traffic count is performed using analysis of motorway toll ticket sales.
See also
*List of bridges by length
This is a list of the world's longest bridges that are more than in length sorted by their full length above land and water. The main span is the longest span without any ground support.
''Note: There is no standard way to measure the total ...
* A9 motorway
References
External links
* {{Structurae, id=20008332, title=Mirna Bridge Plate girder bridges Bridges completed in 2005 Toll bridges in Croatia Buildings and structures in Istria County