Completion of a Tisza cable-stayed bridge in Hungary: light, elegant and technical

Two recent Freyssinet innovations were implemented on M44 Tisza bridge:
  • Multihole deviation saddles allowing the cables to be run from the back spans to the central span, through the pylon.
  • Local Cohesive Strand technology for the cables, allowing a triple corrosion protection barrier of the strands in a targeted manner. This is the first use in Europe of this technology, first introduced by Freyssinet in Asia.

The overall project

The M44 Tisza bridge, with a total length of 556m, consists of:

  • a 306m cable-stayed section with a 152m central span to cross the riverbed,
  • approach spans to allow passage over flood zones.

It has been built over the Tisza River as part of the construction of the new M44 motorway section between Lakitelek and Tiszakürt, about 120 km southeast of Budapest.

As usual for technical projects, our teams joined forces: the supply and installation of the stay cable system, including the saddles, was carried out by Pannon Freyssinet Kft, our subsidiary in Hungary and the Major Projects department in a JV. The local teams were also responsible for the supply and installation of the bridge bearings.

The schedule for the installation of the stay cables in the first half of 2021, which included a preparatory phase from January to March, was perfectly managed.

The main advantages of multihole saddles

  • Outstanding axial and bending fatigue behaviour
  • Durable waterproofing with rainproof connections at saddle ends
  • Preservation of matrix at ultimate cable tension ensured by the UHPFRC cast into the saddle cavities

To describe how it works in more detail, this multihole saddle allows for individual deviation of each tensile element, with the strands passing through the saddle via separate curved cavities. These cavities have a specific cross-sectional geometry ensuring easy threading during installation and high friction during service life. The differential service loads between each side of the pylon are taken up by the friction between the strands and the cavities in the saddle body.

Important note: the positioning of the saddle in the pylon frame is straightforward.

What is the Locally Cohesive Strand (LCS) technology?

The LCS technology is based on the use of Freyssinet Cohestrand technology, which consists of the co-extrusion of a proprietary bonding resin and polyethylene onto the strand, with precise control of the extrusion parameters to achieve a sufficient bond. This process is carried out at Freyssinet’s production sites and is subject to strict quality control. The minimum shear resistance of the compound, between the outer sheath and the seven-wire strand, is 4 MPa at 20°C. This method ensures that the triple barrier strand protection is of industrial quality, consistency and reliability.

The Locally Cohesive Strand technique uses this technology in a targeted manner, to ensure the continuity and redundancy of the corrosion protection through the pylon saddles.