OMAHA, Neb. (AP) — Shippers are praising the proposed changes that federal regulators have approved to the system used to dispute the rates railroads charge. The rules would update the current system that is so costly and cumbersome it is little used. The new procedures the U.S. Surface Transportation Board approved this week may give shippers a way to resolve rate disputes of less than $4 million in a matter of months, instead of years, and at a much lower cost. But major freight railroads expressed reservations about the new system that would take effect sometime early next year.