On June 15th at approximately 2:30 p.m., officers responded to a call of a car/pedestrian collision at 17th Avenue East and East Republican Street.  An 89-year old man was driving southbound on 17th Avenue East, approaching East Republican. That intersection is a 90 degree turn only westbound, which becomes East Republican Street.    A 90-year old man was walking across East Republican Street from south to north in the unmarked crosswalk just west of the 90-degree turn from 17th when he was struck by the car.  The Seattle Fire Department responded to the scene and transported the 90-year old pedestrian to Harborview Medical Center with life-threatening head injury and possible other fractures.  Seattle Police officers and Traffic Collision Investigators responded and investigated.  There were no signs of any impairment or intoxication on the part of the driver.  The Traffic Collision Investigation Squad will conduct the investigation.