The planners had to work very quickly indeed. The lightness of the structure facilitated the construction of this piece of engineering 690 metres long and 29 metres wide. It was all done in record time—just eighteen months to complete work that normally would have taken at least two years. The bridge is also considered a masterpiece of industrial design because it has no apparent supporting structure!
Of German design, the orthotropic bridge runs in a straight line between Mackay Pier and St. Helen's Island. Since the idea of using conventional girders had been rejected, the deck is literally built into the structure of the bridge, reducing the weight by a third, as the structure and superstructure form a single whole. The bridge's five spans were shop-assembled then installed from the two banks by means of a travelling crane that ran along a track. In the narrows next to St. Helen's Island, the river flows beneath the Concordia Bridge at a speed of 12 knots. Sailors have dubbed this part of the river the St. Mary's Current. An invocation perhaps? A plea for help?
Providing rapid access to St. Helen's Island, the Concordia Bridge is one of the world's longest bridges of its kind, and only the second to be built in North America. It offers users a clear view and a striking picture of downtown Montreal and St. Helen's Island. The deck provides a width of 11.6 metres for vehicular traffic and 6.7 metres for pedestrians, plus 9.7 metres for the Expo-Express train during the fair.