sentences:  When it was originally constructed, nearly the entire interchange was built high above the ground because of the cliff existing between the Upper Lachine domain and the Turcot sorting yard overtaking the old Saint-Pierre Lake basin.The highest point of the interchange () is located in its southern part over the Lachine Canal to allow for the passing of ships, but the canal closed its waterway operations just three years later, in 1970.The mean height of the interchange is around , which was, at the time of its inauguration, both the highest freeway interchange in all of Canada and a dramatic demonstration of Montreal's status as a modern global metropolis at the time.