Amtrak is beefing up service in order to accommodate holiday travelers.  They're using every passenger rail car in the fleet, adding trains and adjusting schedules as passengers travel through the Chicago hub.  Officials say the busiest travel days will be next  Tuesday and Wednesday as travelers head out to spend Thanksgiving with friends and family.  Those who plan to travel but haven't yet purchased a ticket should consider traveling the Monday before Thanksgiving and the Friday or Monday after Thanksgiving.  That will give them more travel and pricing options.  Officials say travelers should be prepared for large crowds and they should arrive at the train station at least 45 minutes early.