The use of flashing yellow signal lights late at night and on weekends at intersections in downtown The Dalles will change beginning Friday night.  Starting at 10 p.m. Friday night, traffic signals will flash yellow between 10  p.m. and 6 a.m. seven nights a week.  Under the current schedule, the traffic signals downtown currently flash yellow from 10 p.m. to 8 a.m. Monday thru Saturday, and all-day Sunday.  City officials say the purpose of this change is to increase safety.  The municipal Traffic Safety Commission has received several concerns for the safety of pedestrians and bicyclists crossing 2nd and 3rd Streets at the signalized intersections in the downtown area.  The change has been approved for a trial period to allow for public input.  Feedback to the The Dalles Public Works Department is encouraged.