Before segmental construction entered everyday vocabulary, one project quietly transformed bridge erection. Across the tidal flats of western France, Jean Müller and Campenon-Bernard built the Oléron Viaduct (Pont de l'île d'Oléron) — a 2.86 km prestressed-concrete structure that became the first viaduct in the world erected with a launching gantry (poutre de lancement).

2.86 km
Structure length
46
Spans
79 m
Typical main span
1964
Construction start
Constraint 1
Traditional barge or crane lifting was impractical given the shifting tidal conditions of the Coureau d'Oléron. The site dictated the method.
Müller's solution
A self-advancing overhead steel gantry, resting on the piers and placing precast segments symmetrically to build 79 m spans, span by span — avoiding all contact with the water below.
Precision erection
Each segment was lifted, aligned, and post-tensioned with high geometric precision — entirely from above, without touching the water below.

The concept proved that large viaducts could be erected entirely from above, safely and efficiently — setting the template for modern launching gantries used worldwide today.

The principle Müller demonstrated at Oléron — that precast segments could be assembled span-by-span from an overhead system resting on the permanent piers — became the foundation for subsequent launching gantry development worldwide. The site constraints that appeared to make the project impractical were what forced the invention.

The erection principle proven at the Coureau d'Oléron set the template for how major viaducts are built from above. The method was not adopted because it was obvious. It was adopted because it was demonstrated — here, with precision, under tidal constraint, for the first time.

For further reading on erection engineering applied to bridge construction, see Erection Engineering in Bridge Construction, which places the launching-gantry method used here in a wider sector context.

Related case studies: Akashi Kaikyō Bridge · Woronora River Bridge · Chenab Bridge

The Oleron Viaduct's precast box-girder deck seen from below and behind, carried on a line of tapered concrete piers across the Coureau d'Oleron
The Oléron Viaduct across the Coureau d'Oléron. Its precast segmental deck was erected using the pioneering self-advancing launching gantry described here.
Photo: Mutichou / Wikimedia Commons, CC BY-SA 3.0.
Four-panel schematic of the Oleron Viaduct balanced-cantilever erection sequence: gantry travelling on completed deck toward the next pier, precast voussoirs placed symmetrically either side of that pier, tendons stressed to lock the segment pair, then the gantry advancing to the following pier
Balanced-cantilever erection sequence, Oléron Viaduct, 1964–66: the gantry travels on completed deck, places precast voussoirs symmetrically at the active pier, tendons lock the pair, then the gantry advances.
Original diagram, EE&HL Network. Simplified schematic, not to scale.

Sources: Structurae — structural data and construction dates for the 1964–1966 works. Figures are reported as published.