Gutachtal bridge
The Gutachtal Bridge is a road bridge that forms part of the B31 federal road east of Titisee-Neustadt. The structure spans the Gutachtal valley with the Gutach stream, the state road 156 and the Höllental railway.
Although there had been plans to build a bridge to relieve congestion in Neustadt since 1958, the project was not approved until 1978. The cost of 22 million Deutschmarks was borne by the Federal Government and the State of Baden-Württemberg, which awarded the contract to Polensky & Zöllner and Richard Besemer of Wendlingen am Neckar. The aim of the design was to create a bridge that 'visually blends in with nature without obstructing the view of the Kappl Valley'. The highest bridge in the Black Forest was built between 1978 and 1980 to a design by Hans Wittfoht. It used 18500 m³ of concrete, 1870 tonnes of reinforcing steel and 435 tonnes of prestressing steel. Like the Siegtal Bridge, the superstructure was built as a cantilevered structure with auxiliary steel girders. The gap closure, the meeting of the two ends of the bridge, took place on 24 June 1981. A theodolite was used to take the necessary measurements.
Structure
The bridge has a longitudinal gradient of 4.08% and carries two lanes uphill and one lane downhill. The road in the construction area has a horizontal radius of curvature of 600 metres.
The bridge consists of a 617 m long main bridge with eight spans and a 134.55 m long connecting bridge with four spans. The connecting bridge has a parallel chord box section in prestressed concrete and is supported by circular columns. The transition to the main bridge is on a group pier.