Saaneviadukt (Gümmenen)

Saane viaduct between Gümmenen station (left) and the Saane river (right, flowing upwards to the right), March 2018

The Saane Viaduct near Gümmenen in the canton of Bern in Switzerland is a structure with which the Bern – Neuchâtel railway bridges the Saane valley . For the actual viaduct from 27 masonry natural stone arch bridges also inserted between the sheets of steel are colloquially truss - girder and a subsequent one side of the arched bridges earth embankment counted.

The dam forms the western part of the viaduct, the bridges the eastern part. The girder bridge is located within the eastern half of the arch bridges. The viaduct was built together with the railway line over it at the beginning of the 20th century (opened in 1901).

Within sight of this railway viaduct is a further viaduct over the Saane , downstream with a bridge on the Autobahn 1 (see figure opposite).

history

new truss bridge, piers to be renovated are still scaffolded

There were five drafts made between 1874 and the 1890s for the construction of the Bern – Kerzers section . Variant 2 by the engineer A. Beyeler with a viaduct and three tunnels was chosen and built (completed in 1901). Between 1958 and 1980, the single-track superstructure on the bridges was replaced in several two-year stages by a track trough filled with gravel. Because of the attractive construction of the arched bridges made of natural stone, the viaduct was declared a protected monument.

Part of the bridge to the right of the Saane; the eastern approach is slightly bent

Poster announcing the work on the arched bridges

Since 2013, the line coming from Bern has been upgraded to two tracks and for speeds of up to 160 km / h (previously 90 km / h). In a first stage, the Rosshäuser tunnel to the east was replaced by a new double-track tunnel by 2018 . Since then, the Saane Viaduct has been adapted to this change and renovated at the same time. The steel truss bridge will be replaced by a new bridge of the same type, but with a wider and higher track trough (see illustration on the right). In the east, the steel bridge is given a slightly counter-clockwise twisted approach (see adjacent figure), for which the five-part arch bridge carrying the new track trough is widened on its north side (both the pillars and the arches). In the west, the 22-part arch bridge remains unchanged. On it, the old track trough will be replaced by a new trough of the same width as on the steel bridge and its eastern approach. In contrast to its eastern neighbors, this almost 300 meter long trough will not be made in one cast, but will consist of 90 concrete elements about 3.2 meters wide (in the direction of the bridge). The widening of the earth dam was completed in 2019 as the first measure and with excavated material from the new Rosshäuser tunnel. From mid-August 2020 it will be possible to drive on the viaduct again on a single track. The double-track commissioning and completion of the project will take place in 2021.

Numbers and dimensions

The new numbers and dimensions are given for those affected by the conversion. Of the 22 arches to the west to the left of the Saane, 20 are grouped into four groups of five arches each. The new track rail elements are braced against one another in four groups according to the same pattern . In between there is an expansion joint . Between the groups and on both sides of the steel bridge, the pillars are wider than the others. The pillars at the steel bridge are widened towards the river at a slightly lower height to support the truss bridge girder. The eastern of these pillars will be widened like the subsequent arched bridges on the north side.

The arch bridges are about five meters wide. The inside dimension of the new track trough is a good 10 meters (outside dimension 12 meters). The superstructure of the new bridge thus clearly protrudes on both sides. The steel bridge is 70 meters long (weight 340 tons). The total length of the bridges is about 400 meters, that of the earth dam is about 450 meters.

Web links

Commons : Saaneviadukt (Gümmenen) - Collection of images, videos and audio files

Individual evidence

↑ ^a ^b ^c ^d ^e ^f ^g ^h BLS AG : Renewal of the Saaneviadukt and expansion of the Mauss – Gümmenen double lane
↑ Swiss Amateur Railway Club Zurich SEAK, Bernhard-Ledermann: BLS Saaneviadukt renovation (sixth of seven articles). The drafts not written by Beyeler (2 drafts from B.) obviously did not contain any tunnels.
↑ ^a ^b ^c ^d Baublatt: Saaneviadukt: 340-ton steel bridge
↑ civil engineering: Saane Viaduct: A dam, a stone viaduct and a truss
↑ The sliding trough is slightly trapezoidal when viewed from above. The trough cantilevers on the south side as far as the other troughs, so that the view from the south of the protected monument is only minimally changed.
^ ^A ^b Frutiger AG : Rehabilitation of the Saaneviadukt
↑ In other web sources the length is given as 60 meters or 63 meters.

46.93607 7.24237Coordinates: 46 ° 56 '9.9 " N , 7 ° 14' 32.5" E ; CH1903: 585 055 / 198350

[BLS-1] ↑ ^a ^b ^c ^d ^e ^f ^g ^h BLS AG : Renewal of the Saaneviadukt and expansion of the Mauss – Gümmenen double lane

[2] Swiss Amateur Railway Club Zurich SEAK, Bernhard-Ledermann: BLS Saaneviadukt renovation (sixth of seven articles). The drafts not written by Beyeler (2 drafts from B.) obviously did not contain any tunnels.

[BB-3] Baublatt: Saaneviadukt: 340-ton steel bridge

[4] vil engineering: Saane Viaduct: A dam, a stone viaduct and a truss

[5] The sliding trough is slightly trapezoidal when viewed from above. The trough cantilevers on the south side as far as the other troughs, so that the view from the south of the protected monument is only minimally changed.

[FF-6] A ^b Frutiger AG : Rehabilitation of the Saaneviadukt

[7] In other web sources the length is given as 60 meters or 63 meters.