Drežnik Viaduct

The Drežnik Viaduct is located in Karlovac, Croatia, immediately to the west of the Karlovac interchange on the A1 motorway. It is the longest viaduct in Croatia, spanning 2485 m. It is executed in seven segments (225 m+270 m+4x408 m+358 m long), separated by expansion joints. The viaduct was constructed by Konstruktor, Split, as the main contractor, and Viadukt and Hidroelektra of Zagreb as subcontractors in 2000 and 2001.

The viaduct is executed as two parallel structures, each 10.5 m wide. Their superstructures are continuous structures with spans of 35 m to 70 m m above Kupa River. The carriageway of each of the bridges consists of two traffic lanes 3.75 m wide and two marginal strips 1 m wide. There are no sidewalks and no emergency lanes on the bridge itself. The superstructure is executed in I-section prefabricated reinforced concrete girders, made monolithic with in situ executed transverse beams and the deck slab. The longitudinal girders are mostly of a uniform length (traversing 35 m spans), except for those spanning the river and the longest, 70 m long span. Foundations of the viaduct are executed on piles.

Cost of the construction works related to the Drežnik Viaduct was 250 million Croatian kuna.

The Drežnik Viaduct is the largest and the most significant structure on the Karlovac - Bosiljevo 1 section of the A1 motorway, which carries the transit traffic between Zagreb in the north and Rijeka and Split in the south, and channels it away from the Karlovac city centre, dramatically reducing travel times between those cities and relieving traffic congestion from the D1 state road running through Karlovac, which was especially severe during summer seasons.

Traffic volume
Traffic is regularly counted and reported by Hrvatske autoceste, operator of the viaduct and the A1 motorway where the structure is located, and published by Hrvatske ceste. Substantial variations between annual (AADT) and summer (ASDT) traffic volumes are attributed to the fact that the bridge carries substantial tourist traffic to the Adriatic resorts. The traffic count is performed using analysis of motorway toll ticket sales.