Pont Antoinette

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Coordinates: 43 ° 36 ′ 45 ″  N , 2 ° 6 ′ 41 ″  E

Pont Antoinette
Pont Antoinette
use Railway bridge
Crossing of Agout
place Vielmur-sur-Agout, Sémalens, France
construction Stone arch bridge
overall length 89.25 m
Number of openings a
Longest span 50.00 m
completion 1884
planner Paul Séjourné
location
Pont Antoinette (Occitania)
Pont Antoinette

The Pont Antoinette is a railway bridge over the Agout between the towns of Vielmur-sur-Agout and Sémalens in the Tarn department in the French region of Occitania on the route from Saint-Sulpice-la-Pointe to Castres in the southeast. The bridge is now used by the TER Midi-Pyrénées regional express trains .

description

The stone arch bridge crosses the Agout with a single large and strikingly slender segment arch with a span of 50.00 m, the apex of which is 11.50 m above the low water . The arch is pulled down into the stable ground on the banks of the river in order to save particularly expensive abutments . The bridge foundations reach up to 4.80 m below the level of the low water. On both halves of the arch there are five round arches made of bricks and provided with profiles, each with a span of 4.00 m, which in turn supports the bridge table, which is emphasized by its own profile, and connects to the tracks on land. The 89.25 m long bridge deck is bordered at the side by a balustrade .

history

With the construction of the bridge from Le Castelet in the Ariège department in the Pyrenees , the Viaduc de Lavaur , located on the same railway line around 27 km further north-west, and the Pont Antoinette in the years 1882 to 1884, Paul Séjourné , who was only 33 years old, gained wide recognition for the further development of the construction of stone arch bridges. As a special honor, he was allowed to name this last bridge after his wife's first name.

In the case of bridges with increasing spans, the falsework , which is supposed to carry the weight of the complete arch , naturally becomes larger, more complex and more expensive. In order to keep this within limits, Séjourné used the method, which was already known to the Romans but had been forgotten again, of initially only building a thin layer of arches on a comparatively light falsework. This layer can then bear its own weight and that of the next arch layer and thus itself take on the function of the falsework.

Another innovation was the complete opening of the arch gussets . Séjourné mentions older models for this, in which the openings were rather narrow passages in order to reduce the lateral water pressure on the bridge during floods. A closed gusset filled with masonry contributes little to the stability of the bridge, but significantly to its weight, which has to be borne by the arch. Séjourné therefore replaced the brick gussets with five round arches each supported by narrow pillars. He created the model for many later arch bridges not only made of stone, but also of concrete .

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