NEW YORK — A panel of trucking executives painted a generally optimistic outlook for the nation’s economy based on recent freight trends.However, they said, some truckers aren’t expanding their fleets to meet the growing demand and instead are focusing on improving profits by raising rates or better utilizing existing equipment.The executives spoke at a Global Transport and Logistics Conference attended by dozens of in-vestors and shipper representatives and sponsored by the investment firm Bear, Stearns & Co.For the full story, see the May 27 print edition of Transport Topics. Subscribe today.