Freybrücke

About

The Freybrücke (lit. English: Frey Bridge) is an arch bridge located in the Wilhelmstadt district of the Berlin borough of Spandau. It carries Heerstraße (federal road 2/5) over the Havel and Havelseenweg, connecting Pichelsdorf with the Pichelswerder peninsula. The structure spanning 157.90 meters, serves about 60,000 motorists daily. The original road bridge, measuring 174 meters in length, was built in 1908-1909 based on plans by civil engineer Karl Bernhard. Despite being designated as a listed structure, this older bridge was demolished due to significant damage, driven by economic considerations as of 2014. The new bridge, retaining the same name, was inaugurated in December 2016. Initially referred to as the Havelbrücke (Havel bridge), the bridge was renamed Freybrücke in 1913 by a decision of the Osthavelland district. This renaming was intended to pay tribute to the "meritorious leader" of the construction of the Döberitzer Heerstraße (today known as Heerstraße), the Geheime Oberbaurat Adolf Frey.

Döberitzer Heerstraße and development of the Pichelswerder

Freybrücke was part of the overall project Döberitzer Heerstraße, which was built between 1903 and 1911 as an extension of the Kaiserdamm as a direct connection from the Berlin Palace via the cities of Charlottenburg and Spandau, which were independent until their incorporation into Greater Berlin in 1920, to the military training area Döberitz. The east-west roadway encompasses present-day roads such as Unter den Linden, Straße des 17. Juni, Bismarckstraße, Kaiserdamm, Heerstraße, and, upon exiting the Berlin city limits, Hamburger Chaussee in Dallgow-Döberitz.

At the time of its construction, the bridge site fell within the jurisdiction of the Osthavelland district. While the military, financial, and forestry treasury, along with Berlin, Charlottenburg, Spandau, the Teltow district, the Osthavelland district, and various municipalities, all contributed financially to the overall project, the primary funding for the bridge lay largely with the forestry treasury, which the Berlin Monument Database indicates as the builder of the bridge.

The road, built for military reasons, was public from the beginning and made the western Grunewald and Pichelswerder accessible to the broad Berlin and Spandau excursion traffic. Pichelswerder, in particular, had long exerted a great attraction on Berliners. Thus, as early as 1806, when Johann Christian Gädicke described the "Pichelsdorfsche Werder, im Havelländischen Kreise, bei Spandau" in the Lexicon von Berlin und der umliegenden Gegend, stating: "This area is a popular destination for leisure and is considered one of the most beautiful areas surrounding Berlin".

The most significant technical and financial challenge in road construction was the bridging of the Havel lowlands at the northwestern foothills of the Teltow plateau. Among several variants, including an additional 250-meter-long bridge over the Scharfe Lanke (with a straight continuation of the Heerstraße at the Scholzplatz), the planners opted for a slight bend in the Heerstraße to the northwest and thus for a routing that managed with two bridges. The neighboring Stößensee Bridge, about 800 meters to the east, spans the Stößensee, an old arm of the Havel River. A dam, around 450 meters long was built in the lake from Pichelswerder, reducing the length of the Stößensee bridge to 100 meters. The 174-meter-long Freybrücke crosses the Havel River, which was canalized in this area in 1880/1881, as well as the Havelseenweg, a pedestrian and bicycle path leading from Pichelswerder between the river and the Tiefwerder Wiesen to the village of Tiefwerder. While the most expensive variant for bridging the Havel lowlands involved the large bridge over the Scharfe Lanke, with an estimated expense of 16.9 million marks, the implemented solution cost a comparatively low sum of 2.54 million marks. Freybrücke accounted for 1.14 million marks (adjusted for purchasing power in today's currency: around 7 million euros).

Freybrücke was part of the overall project Döberitzer Heerstraße, which was built between 1903 and 1911 as an extension of the Kaiserdamm as a direct connection from the Berlin Palace via the cities of Charlottenburg and Spandau, which were independent until their incorporation into Greater Berlin in 1920, to the military training area Döberitz. The east-west roadway encompasses present-day roads such as Unter den Linden, Straße des 17. Juni, Bismarckstraße, Kaiserdamm, Heerstraße, and, upon exiting the Berlin city limits, Hamburger Chaussee in Dallgow-Döberitz.

At the time of its construction, the bridge site fell within the jurisdiction of the Osthavelland district. While the military, financial, and forestry treasury, along with Berlin, Charlottenburg, Spandau, the Teltow district, the Osthavelland district, and various municipalities, all contributed financially to the overall project, the primary funding for the bridge lay largely with the forestry treasury, which the Berlin Monument Database indicates as the builder of the bridge.

The road, built for military reasons, was public from the beginning and made the western Grunewald and Pichelswerder accessible to the broad Berlin and Spandau excursion traffic. Pichelswerder, in particular, had long exerted a great attraction on Berliners. Thus, as early as 1806, when Johann Christian Gädicke described the "Pichelsdorfsche Werder, im Havelländischen Kreise, bei Spandau" in the Lexicon von Berlin und der umliegenden Gegend, stating: "This area is a popular destination for leisure and is considered one of the most beautiful areas surrounding Berlin".

The most significant technical and financial challenge in road construction was the bridging of the Havel lowlands at the northwestern foothills of the Teltow plateau. Among several variants, including an additional 250-meter-long bridge over the Scharfe Lanke (with a straight continuation of the Heerstraße at the Scholzplatz), the planners opted for a slight bend in the Heerstraße to the northwest and thus for a routing that managed with two bridges. The neighboring Stößensee Bridge, about 800 meters to the east, spans the Stößensee, an old arm of the Havel River. A dam, around 450 meters long was built in the lake from Pichelswerder, reducing the length of the Stößensee bridge to 100 meters. The 174-meter-long Freybrücke crosses the Havel River, which was canalized in this area in 1880/1881, as well as the Havelseenweg, a pedestrian and bicycle path leading from Pichelswerder between the river and the Tiefwerder Wiesen to the village of Tiefwerder. While the most expensive variant for bridging the Havel lowlands involved the large bridge over the Scharfe Lanke, with an estimated expense of 16.9 million marks, the implemented solution cost a comparatively low sum of 2.54 million marks. Freybrücke accounted for 1.14 million marks (adjusted for purchasing power in today's currency: around 7 million euros).

Bernhard's aesthetic steel construction without architects

Drawn by inspiration from the Parisian road bridges during his visit to the 1900 World's Fair, Karl Bernhard went on designing 'pleasing iron bridges without architects,' whose lines were to be achieved only 'through the interplay of static and aesthetic considerations.' In 1903, for the Treskow Bridge, he developed a truss arch featuring a tension band and suspended central span. This innovative approach composed the load-bearing elements of the bridge, utilizing iron girders beneath the side arches. Bernhard employed this same structural system for both the Stubenrauchbrücke (Stubenrauch Bridge) and the Freybrücke. However, for the neighboring Stößenseebrücke (Stößensee Bridge), Kaiser Wilhelm II opted for a distinct system—cantilever girders with appended towed girders—choosing an alternative over Bernhard's proposals. With the Freybrücke, Bernhard further developed the concept of the Treskow Bridge:

"If there is a question of the connection of floor girders above the carriageway of the central opening with girders lying below the carriageway, here there are five openings in such a way that on both sides of the floor girders of the central main opening, there are two side openings each with corresponding girders. The wide-span arches of the central opening alone project above the roadway, while the main girders of all four side openings lie below the roadway, giving the entire bridge appearance a characteristic emphasizing the river opening."

— Karl Bernhard: Stossensee and Havel Bridge as part of the Döberitzer Heerstraße. 1911

Originally, the plan involved spanning only the Havel with a 65-meter bridge, while the lateral peat masses were to be shifted through sand fills. However, the fears arose that the fills could remain in motion for a long time and endanger the stability of the piers. The bridge was extended over the banks on both sides until a load-bearing foundation soil was achieved for the embankment fill and end piers. In the bank area, the thickness of the bog layers reached up to eight meters, while at the chosen location of the end piers, it was only around 1.25 to 2 meters thick. This resulted in a central opening of 63 meters and two land openings of 31.5 and 18.9 meters, yielding a total bridge length of 163.8 meters.

The bank piers support the two main beams of the central opening, and due to their considerable spacing, each consists of two single piers. The piers located between the bank and end piers carry four supports and, accordingly consist of four individual piers. These piers rest on a coherent foundation body. Additionally, staircases are attached to each of the four end piers. All piers are founded by air pressure and were executed by Philipp Holzmann & Co. of Frankfurt am Main.

Roadway and the two main girders spanning 63 meters, 2009

View from the Frey Bridge to the Havel and the Tiefwerder Wiesen (right)

During high water, a clearance of four meters needed to be maintained for Havel shipping. This prevented the arrangement of the 63-meter-wide main girders under the bridge. As a result, the main girders were placed on either side of the 16-meter-wide roadway, resulting in a main girder spacing of 17.60 meters, which was unusual for the time. In the side openings, the supporting structure lies below the roadway. The arrangement was made in such a way as to allow the future construction of riverside roads. The upper edge of the carriageway at the center of the bridge was 37.427 meters above sea level, while the lower edge of the structure was 35.25 meters above sea level. The bridge had a one-sided slope of 1:270, which had to be increased to 1:50 from the riverbank to reach the base of the ramp. The Heerstraße does not cross the Havel at right angles, and since the piers were nevertheless to be parallel to the bank, the two main girders of the central opening were adjusted by 2.48 meters in the longitudinal direction of the bridge. This gave the cantilevers on the main girders varying lengths.

The thrust of the two-hinged arch above the central opening is taken up by a tension band that engages the first node of the bottom chord. The arch stands at a height of 4.35 meters above the two supports and 1.60 meters in the center. The arrow height of the bottom chord measures 10.57 meters. The spans of the openings are: end openings 18.90, side openings 32.74 as well as 30.26, and center opening 63 meters. The truss arches within the central opening are filled with a post-truss design, while the main beams of the side openings and cantilevers utilize a strut truss configuration.