Four dead in head-on crash on Stoney Trail as investigators explore two theories

Four people died in a head-on collision on Stoney Trail late Sunday, including a child, after a 2011 Mercedes-Benz travelling southbound crossed into northbound traffic near the Glenmore and Sarcee interchange.

The Mercedes, driven by a 30-year-old man with his wife and child as passengers, struck a 2016 Subaru Impreza head-on. The Subaru's 43-year-old driver was killed. Both vehicles caught fire. A third vehicle, a Chevrolet Equinox, then struck the Mercedes; its 52-year-old driver and three youth passengers were taken to hospital. One person suffered life-altering but non-life-threatening injuries.

Police collision reconstructionist Const. Scott McCallum has developed two theories about how the Mercedes entered the northbound lanes. The first: the vehicle veered off the southbound road and crossed the wide, uneven median. "If that makes sense, you'd be very aware that you were driving somewhere that you shouldn't," McCallum said. However, tire marks in the median have been eliminated as evidence due to the probability of other vehicles making them.

The second theory—which McCallum considers more likely—is that the car had been southbound from north of the Glenmore and Sarcee exit, entered the roadway erratically, then straightened up before making a different tire mark. "The problem is the tire marks don't go all the way to that," McCallum said.

Electronic data has been recovered from the Mercedes and Chevrolet through their Event Data Recorders, though the Subaru was destroyed by fire. McCallum is now interpreting that data alongside physical evidence and vehicle damage to confirm his observations. Determining the driver's intent—whether behaviour was deliberate, distracted, or impaired—remains the work of the primary investigator, who will examine cellphone records, traffic camera footage, and any prior incidents. The investigation is ongoing.