Murrtalviaduct

The Murrtalviaduct, known locally as the Murrtalviadukt, stands as a magnificent testament to engineering prowess and historical evolution in the picturesque region of Backnang, Baden-Württemberg, Germany. This impressive structure, which spans the tranquil Murr Valley, is not just a bridge but a narrative of resilience, innovation, and architectural brilliance that has evolved through the decades.

The First Murrtalviaduct (1938–1945)

The original Murrtalviaduct was constructed between 1937 and 1938 as part of the Reichsstraße 14 to serve as a bypass for the town of Backnang. This initial structure was a marvel of its time, featuring two consecutive arches and ramp bridges on the hillside. Both the superstructure and the supporting arch construction were crafted from reinforced concrete, with an impressive arch span of 105 meters. At a width of 9 meters, it was narrower than the current bridge but was celebrated as one of the largest reinforced concrete arch bridges in Germany. The Stuttgart-based company Baresel was entrusted with its construction. Tragically, as World War II drew to a close, the bridge was demolished by Wehrmacht units on April 19, 1945, to hinder the advancing Allied forces.

The Second Murrtalviaduct (1949–2011)

In the aftermath of World War II, the need to restore critical infrastructure led to the rapid reconstruction of the Murrtalviaduct. Starting in 1948, the bridge was rebuilt at the same location, incorporating some surviving sections of its predecessor. The new structure featured a mix of old and new elements, with the superstructure of the approach bridge retained in reinforced concrete, while the two main arches were constructed in steel. The bridge deck was a composite steel construction, and by 1949, the viaduct was once again fully operational.

Between 1983 and 1985, the bridge underwent a widening project to accommodate increasing traffic demands, particularly from heavy vehicles. The width of the superstructure was expanded to a uniform 11.5 meters. Despite these improvements, the bridge eventually struggled to cope with the growing traffic load, leading to restrictions such as a minimum distance of 50 meters for trucks. Regular maintenance became a necessity, and by 2009, plans for a replacement structure were set in motion. The new bridge, which took over traffic duties in August 2011, marked the end of the second Murrtalviaduct’s service. Demolition of the old bridge began in November 2012 and was completed by May 2013.

The Third Murrtalviaduct (2011)

The third iteration of the Murrtalviaduct was part of a broader plan to expand the Bundesstraße 14 to four lanes between Backnang-Waldrems and Backnang-West. Designed by the renowned firm Leonhardt, Andrä und Partner, construction of the new bridge commenced in September 2009. Positioned just west of the old viaduct, this new structure stands 27 meters tall, slightly lower than its predecessor but extending 419 meters in length, making it 16 meters longer.

The new viaduct is a fine example of semi-integral bridge design, where the structure is viewed as an interactive whole rather than segmented systems. It features two large, consecutive pairs of arches with spans of 107.57 meters, flanked by ramp bridges measuring 91.88 meters and 111.58 meters respectively. The superstructure is a continuous two-girder slab beam with a construction height of 1.20 meters. The four supports on each arch rib are partially connected to the arches and superstructure with concrete joints. The superstructure is monolithically connected to the piers of the ramp bridges, allowing for minimal movement due to the flexibility of the tall piers. Some piers were founded 2 to 3 meters deeper to achieve the necessary height and flexibility. Bearings are only present at the two abutments.

The new Murrtalviaduct was opened to traffic on August 22, 2011. With the new bridge in operation, the dismantling of the sixty-year-old temporary structure began.

The Fourth Murrtalviaduct (since 2023)

In September 2016, funding was approved for the four-lane expansion of the Bundesstraße 14 between Backnang-Waldrems and Backnang-West. The Stuttgart Regional Council announced that construction of the second directional carriageway would begin in mid-2018. After several delays, the bridge construction finally started in April 2023 with a symbolic groundbreaking ceremony. The completion of the new bridge is scheduled for 2025, with the opening to traffic planned in conjunction with the four-lane expansion up to the Backnang-West junction in 2027.

The Murrtalviaduct is more than just a bridge; it is a symbol of engineering excellence and historical significance. Each iteration of the viaduct tells a story of its time, reflecting the technological advancements and challenges faced by its builders. As you traverse this architectural marvel, you are not just crossing a bridge but journeying through a rich tapestry of history and innovation that continues to shape the landscape of Backnang.