Bridges

With a total length of 2551 m, the bridge over the Beauharnois Canal is the main structure of the Nouvelle Autoroute 30 project in Montreal (Canada). It crosses the Beauharnois canal and the St-Laurent Seaway, which is the only waterway communication between the Great Lakes of North America and the Atlantic Sea. This crossing of 150 m has governed the design and construction of this project.

The paper starts with a brief introduction to the incremental launching technique to allow the reader to understand the basic concepts of this method. Then, in the main point of the paper, the key facts of the design and construction of the incremental launching procedure to fabricate and put in place two steel box girders of 1456 m and 7400 t are explained. In an effort to allow the reader to use the experience of this project in the future in similar scenarios, several particularities are explained:

• The technical and administrative constraints to cross the Saint Laurent Seaway.
• Equipment used during the launch of the typical spans (82 m).
• The requirements to be able to launch the box girders over the main span of 150 m.
• The procedure to make the launch feasible with a parabolic curve in the bridge elevation.
• Description of the assembling process at the launching yard.
• The particularities to use the incremental launching techniques in cold weather.
• The use of hybrid mechanical joints mixing welding and bolting.
• The control of monitoring methods of the launching.

The last part of the paper presents some of the main conclusions and lessons learned from these engineering works.