Chances are you will never reach the posted 35 mph speed limit on Argonne Road between Mission and Trent avenues. A traffic study almost completed by the public works division of Spokane Valley shows that most drivers travel at speeds between 10 and 12 mph on that stretch, making it one of the most congested areas in Spokane Valley. “About 42,000 vehicles travel over the two-lane bridge at Argonne every day,” said Sean Messner, senior traffic engineer with Spokane Valley, “bringing us very close to capacity there.”