Length is derived from the difference between the locations of the northbound Macleod Trail bridge over Deerfoot Trail (located at a mileage of 2.456 km on the section of Highway 2 known as "2:15") and the southbound Deerfoot Trail bridge over westbound Stoney Trail NE (located at a mileage of 48.859 km on section "2:15"), a distance of 46 kilometers .