For Commuters Thanks to a renovation and redesign, passengers can enter the station and board the trains in a minute or two. The upgrade separated slow-moving Amtrak passengers who are unfamiliar with the station from those racing to catch commuter trains. In the morning all the station escalators travel upward so passengers can get from their trains to the mezzanine level and then to street level quickly. Most passengers exit the station from the downtown sides--either the Jackson Boulevard or Adams Street exits on Riverside Plaza--and walk over the river into the Loop. In the evening the flow of traffic is reversed and the escalators move downward. Well-marked elevators are available for people moving against the flow of traffic or requiring special assistance.   Escalators change direction morning and evening to speed commuters through the station.   Getting Your Ticket Ticket booths are located just off the Great Hall and are open from 6am to midnight, Monday through Friday, and 7am to midnight on Saturdays and Sundays. You can pay by check as long as you are spending more than $10. You can also buy 10-ride tickets by mail (pick up a mail-order form at the station) or on the Web. If you're in a rush, you can save time by buying your ticket on board, but this convenience costs an extra dollar and only cash is accepted. Transportation from Station Taxis can be found at the cab stand on the western edge of the north concourse, but during rush hour you'll have to wait your turn in a fast-moving line. Blue Line Two blocks south of the station at Clinton Street and Congress Parkway. Orange, Brown, Purple Three blocks east of the station at Quincy and Wells streets. By John Gerard McLaughlin Photos: Steel Bokhof