The Krk Bridge links the Croatian mainland with the island of Krk in two reinforced concrete arches that meet on the small island of Sveti Marko. The larger arch spans 390 m, or about 416 m if the part of the arch below the waterline is counted; at its crown the deck stands about 67 m above the sea. The second arch spans 244 m. The total length is about 1,430 m. Ilija Stojadinović designed it with Vukan Njagulj and Bojan Možina, and Mostogradnja of Belgrade and Hidroelektra of Zagreb built it between 1976 and 1980. It opened on 19 July 1980.

Wikipedia records the main span as the longest concrete arch at the time of construction, until the Wanxian Bridge in China surpassed it in 1997. The record belongs to the finished arch. The construction story is about the years before closure, when neither half could act as an arch at all and each had to be held in place as a cantilever.

390 m
Main arch span
≈67 m
Deck above sea at crown
244 m
Second arch span
1,430 m
Total length
1980
Opened
Phase 1 — The supports
Prefabricated foundations, slipformed piers
A 1981 account in Građevinar describes the foundation of the arch on prefabricated concrete elements weighing over 600 tons each, and very slender, tall piers concreted by slipforming.
Phase 2 — The cantilevers
An arch built as a truss
A 1979 account in Bauingenieur describes how each half was built outwards as a cantilevered truss. The arch members and the future deck columns worked in compression, while stressed cables anchored in the rock worked in tension. Until closure, the arch members formed part of a temporary truss rather than a working arch.
Phase 3 — The ropeway
Segments delivered from above
The same account describes the precast segments being placed by a specially constructed wire ropeway spanning the crossing. That made the delivery system as much a part of the erection scheme as the cantilevers themselves.
Phase 4 — The closure
Ties removed, the arch takes over
Once the two halves were closed at the crown, the tie-back cables were removed and the structure began to carry load as an arch. Structurae reports that the arch was later raised by jacks, by 63 mm after two years and by an additional 93 mm a year later, to counter creep and shrinkage.
Four-phase schematic of the Krk Bridge: arch foundations on prefabricated elements of more than 600 tons and slipformed piers; each half of the 390 m arch built as a cantilevered truss with stressed cables anchored in rock; precast segments placed from a purpose-built wire ropeway overhead while the ties stay in place; and closure at the crown, with the deck about 67 m above the sea, after which the temporary cables were removed
An arch built as two tied-back cantilevers. Conceptual schematic, not to scale; the number and layout of ties and deck columns are not drawn from the project.
Sources: Noelting, Bauingenieur (1979); Sram, Građevinar (1981); Structurae; Wikipedia. Diagram: EE&HL Network, 2026.
Tap or click the diagram to open it full size.

At Krk, arch action depended on closure. Until then, each half worked inside a temporary tied-back cantilever system that carried the forces the arch would later carry itself.

Cantilevered arch erection with temporary ties is a recognised method for long concrete arches, and Krk is an early large-scale example of it; Wikipedia describes the bridge as designed as a cantilever bridge with temporary cable-stays. The sources reviewed describe the system but not the stage-by-stage tie forces, the closure tolerances or how geometry was controlled as the cantilevers grew. Those details are not given here.

The later jacking is worth noting. The arch was adjusted twice in its first years to correct the effects of creep and shrinkage, which shows that the geometry fixed at closure was not the final geometry. For a concrete arch, as for a concrete cantilever, construction-stage decisions continue to shape behaviour after the temporary works have gone. That is an editorial reading.

For other arches closed in the air, see the Gateway Arch and Chenab Bridge case studies. For the general question of releasing temporary supports, see What Is a De-Propping Sequence? and Temporary Works & Erection Strategy.

Related case studies: Chenab Bridge · Gateway Arch · Koror–Babeldaob Bridge · Hoover Dam · Beijing National Stadium

Core concepts: What is erection engineering? · What is heavy lift engineering?

The Krk Bridge seen from the sea: the smaller and larger concrete arches either side of the rocky islet of Sveti Marko, with the deck carried on slender columns above each arch
The two arches of the Krk Bridge, either side of the islet of Sveti Marko. Resized from the original for web display.
Photo: Toffel, via Wikimedia Commons; public domain.

Sources: Bauingenieur — Noelting, D., vol. 54, no. 8, 1979, p. 314 (TRID abstract) — cantilevered trusses, cables anchored in rock, removal after closure, wire ropeway; Građevinar — Sram, S., vol. 33, no. 2, 1981, pp. 77–106 (TRID abstract) — precast elements, foundation elements over 600 t, slipformed piers; Structurae — Krk Bridges — second span, jacking of the arch after two and three years; Wikipedia — Krk Bridge — designers, contractors, dates, main span and 416 m figure, clearance, total length, record until Wanxian, temporary cable-stays. The erection method is taken from the abstracts of the 1979 and 1981 papers; the full papers were not consulted, and details of tie forces, closure and geometry control are not given here. Sources label the 67 m figure differently: Wikipedia gives a clearance below of 67.02 m, and Structurae lists 67 m as the rise. These are different geometric quantities. This page follows the 1979 abstract, which gives the deck at the crown as approximately 67 m above the sea channel, and does not present the figure as a verified arch rise. Material quantities are omitted from this account. An earlier version of this story appeared as a LinkedIn post.

Frequently Asked Questions

According to a 1979 account in Bauingenieur, each half was built outwards as a cantilevered truss: the arch members and future deck columns in compression, and stressed cables anchored in the rock in tension. Precast segments were placed from a specially constructed wire ropeway. After the arches were closed the temporary cables were removed.

The main arch spans 390 m, or about 416 m if the part of the arch below the waterline is counted. At the crown the deck is about 67 m above the sea. The second arch spans 244 m and the total length of the bridge is about 1,430 m.

Wikipedia records its main span as the longest concrete arch at the time of construction, until the Wanxian Bridge in China surpassed it in 1997.

Structurae reports that the arch was raised by jacks by 63 mm after two years and by an additional 93 mm a year later, to counter the effects of creep and shrinkage.