Steel Assembly Starts at Nagerl Bridge in the Bavarian Forest Region
12. January 2026
Important milestone at the replacement of railway bridge over Schwarzer Regen river
The starting steel assembly at the construction site marks an important milestone for the replacement of the railway bridge over Schwarzer Regen river (Nagerl bridge).
The existing Nagerl bridge was built in 1877 and crosses the river Schwarzer Regen with a span width of 72 metres. The superstructure consists of a single-span riveted steel truss and is founded on concrete abutments on footings.
The design of the new structure plans a three-span truss bridge (span widths 28m – 64m – 28m) following the existing alignment. The superstructure will be a steel truss with deck slab on top and variable structural height. The new steel superstructure has a total weight of around 760 tonnes.
The designed three-span girder with its concise and varying course of the truss’s lower chords, crosses the Schwarzer Regen valley in an elegant and transparent way. The short edge spans with descending structural height and small, offset abutments replace the enormous cubature of the old abutments.
The load-bearing concept has been developed to implement the replacement structure with minimal interferences into railway operations and the environment – especially the Schwarzer Regen river.:
The new, smaller abutments can be erected during a short construction period and independently of the dismantling of the old abutments. The main span with narrowing structural height towards the centre is suitable for a cantilever construction from both sides as well as assembly by crane of a longer centre section. The superstructure will be preassembled next to the existing rail line and launched into its final position together with the piles during a railway closure. Train traffic will continue until this closure via the old structure which will be dismantled during the same close-off period.
The bridge’s construction site is isolated, rough and difficult to access. The required site development includes site roads of more than 1 kilometre length, ramps, working levels, construction site facilities and provision areas as well as two temporary bridges for construction site traffic over Schwarzer Regen river.
Nagerl bridge together with Ohetal viaduct and Deffernik bridge are a compendium of three viaducts on the railway line Landshut – Bayerisch Eisenstein, which replacements are all designed by SSF Ingenieure.
