CHICAGO --There was a traffic alert for parts of downtown Chicago Thursday night.More than 26,000 people will be taking part in the 27th annual Corporate Challange Run. They will represent 633 companies. The three-and-a-half mile race begins at 7:10. Columbus will be closed between Balbo and Roosevelt until 10:30 p.m. Other streets will close and then open as runners pass through. Those streets include: Monroe, Randolph, Wacker Drive and Congress.