Lattice bridges in timber construction

Lattice bridges are especially suitable for span widths of 20 to 70 m.

Their special design makes them into an architectural jewel: Lattice bridges are part of the scenery in many regions.

The lattice elements are contiguous supporting structures. They offer the advantage that they have a lower material consumption than comparable full-wall constructions such as beams and they accordingly have a lower tare weight. The construction generally consists of laminated timber for the upper chord, lower chord and posts, and is mostly braced horizontally with steel diagonals. The roadway is connected to the lower chord. Lattice bridges typically have a low construction height.

Lattice bridges

Construction of the upper chord, lower chord and posts from laminated timber
Loading of the bars of the lattice system on the basis of tension and compression
Horizontal bracing with steel diagonals
Assembly of the individual components with slotted sheet metal and bolt connections
The walkway is connected to the lower chord
Design of the road surface with open decking or as a sealed mastic asphalt surface
Fitting of the railing to the side of the lattice girders
Covering with sheet metal, bricks or wooden shingles

Geschütztes Haupttragwerk

Structural timber protection is the key to the longevity of a timber bridge. Structural timber protection intends for all structural timber components to be completely protected. In this respect, the following steps are taken into consideration: Installation of technically dried timber with a timber humidity of 12% in order to prevent insect infestation, protection against weathering, ingress of moisture, UV rays due to the installation of projections and skirting in the design as well as good air circulation to encourage drying out. Constructions designed in this way satisfy the requirements of protected timber bridges pursuant to DIN EN 1995-2 NA. This means that loss events are prevented and maintenance costs are minimised, and the use of timber preserving chemicals can be reduced and/or avoided. Structures protected according to DIN EN 1995-2 have a service life of 60 - 80 years*. With lattice bridges, the protection of the supporting structure is generally guaranteed by the casing, which is the cover and the additional side formwork.

* Source: Redemption amounts calculation regulations - ABBV, BMVBS, status 2010 and study of DGfH 2006

Advantages of the lattice bridge:

span widths of 20 to 70 m.
low construction height
Low material use with high performance
Optimum structural timber protection due to the flat or pitched roof on the upper chords
Roadway surface protected against weathering, omitting the need for possible winter road clearance