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Heritage classified

Key figures

Origin and history

The Boutiron Bridge, or Boutiron Bridge, is a reinforced concrete road bridge on the Allier, inaugurated in 1913. Located downstream of Vichy, it connects the communes of Creuzier-le-Vieux (right bank) and Charmeil (left bank) via RD 27. This bridge marks a major innovation: Eugène Freyssinet applies its Freyssinet joints for the first time, with straitened concrete sections allowing a slight rotation of the arcs. It has been listed as a Historic Monument since 2021.

The construction of the Boutiron Bridge (1912-1913) followed that of the Veurdre Bridge (1911-1912), where Freyssinet had observed the effects of concrete creep, a phenomenon that was then unknown. For Boutiron, it adapts its design by adding narrow sections to the birth of the arches, allowing a plastic rotation of the concrete. During the work, a flood of Allier tests the resistance of the work in progress: the hangers, distorted by the violence of the current, resume their initial form after Freyssinet intervention, confirming the plasticity of the material.

The Boutiron Bridge is part of a larger project led by entrepreneur François Mercier and the Allier General Council. After discovering the model of the bridge at Freyssinet, Mercier proposes to replace three problematic suspended bridges on the Allier with reinforced concrete structures, at the cost of a single bridge. The contract is concluded, and Freyssinet oversees the work. The bridge, still in service today, illustrates the economy of materials and the durability of reinforced concrete: its original guardrails, open in the shape of V, are intact after a century.

In 2012, work to strengthen the pillars (€315,000) was carried out to preserve the structure. In 2021, portals were installed to prevent the passage of trucks over 3.5 tons, which had been banned for a long time. Despite these constraints, the bridge remains an exceptional testimony of the beginnings of reinforced concrete and the innovative engineering of Eugene Freyssinet.

Prior to the Boutiron Bridge, a first structure in 1854, carried by a flood of the Allier River, had been replaced in 1857 by a hanging wooden deck bridge. The bridge served until the current bridge was built. The Boutiron site, strategic to cross the Allier, had previously housed a ferry. The Boutiron Bridge, with its three uneven arches (67 m - 72 m - 67 m), rests on two piles and two abutments, and its apron was decimated by verinage of the keys, a technique controlled by Freyssinet after the experience of the Veurdre Bridge.

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