Challenges of Design and Construction of the Boulevard des Galeries d’Anjou Overpass over Highway 40 in Montreal

The Boulevard des Galeries d’Anjou overpass is located over the metropolitan Highway 40 in Montreal. The bridge was built as a replacement of an existing three-span prestressed concrete deck bridge. The construction of the bridge in such urban area and over one of Canada’s busiest highways brought many design challenges and the necessity for use of innovative construction methods. It was demonstrated that the option of 61.2 m single-span bridge offered the best solution for both mobility in the area and future development needs. Thus, no long-term lane closures are required on Highway 40 during construction in addition to providing a wider vehicle space. The most restrictive design criterion was to provide 5.1 m vertical clearance as required by the provincial standards while the existing bridge had a vertical clearance of 4.6 m. Furthermore, the existing bridge has suffered from truck impact in the past years, and it was imperative to raise the new one. It was demonstrated that the design and construction of a conventional single-span bridge was not possible without the reconstruction of the existing approaches and the neighboring intersections in spite of having unsafe approaches’ slopes. To meet the geometrical criteria together with safe approaches’ slopes, the structure was designed and built using an innovative construction method which consisted of the use of a temporary support at the center of the bridge and temporary bearings at the abutments during the first stage of construction. Thus, the box girders of the superstructure were designed and constructed as two-span girders during the first construction stage until the deck slab was poured and reached the required resistance. Then, the temporary support was removed to obtain the single-span structure. This allowed to optimize the design and to have a thinner deck compared to the conventional single-span bridge. This paper will provide an insight on the design and construction challenges related to staging construction such as monitoring load distribution during the construction phases. The controlling of concrete temperature poured in cold weather conditions and cured under heated shelter will be also presented.