Calgary police say an 18-year-old man hit by a vehicle on Nose Hill Drive N.W. on Tuesday morning was changing his tire when he was struck, suffering life-altering injuries. The collision happened by a Home Depot near Tuscany Hill N.W. at 8:45 a.m. The victim was changing his tire in the left-hand lane of eastbound Nosehill Drive when he was hit from behind by an eastbound Subaru Impreza. Acting Sgt. Mike Kornelson with the Calgary Police Service traffic unit says bystanders helped the victim until first responders arrived on scene. Paramedics transported him to hospital in life-threatening condition. He remains in hospital in serious but stable condition, Kornelson said Tuesday. The driver of the Impreza, a man in his 40s, remained on scene. Police say a passenger in the Impreza was transported to hospital as a precaution. Investigators don’t believe speed or impairment were factors in the crash. “We like to advise drivers that if you do have a mechanical issue with your vehicle or if you need to change a tire, that you ensure you stop in a safe area – so into the shoulder, away from traffic – and have your four-way flashers on,” Kornelson said. “And if you don’t deem it safe, just stay in your vehicle.” “Road safety is everyone’s responsibility.” Kornelson said. “We have to start looking out for each other.” Anyone with further information or dash-cam footage of the incident can call police at 403-266-1234. Tips can also be submitted anonymously through Crime Stoppers.