A federal judge ordered more than 50 Amtrak maintenance workers back to work, hours after a strike over layoffs disrupted train service in parts of New England and New York. Judge Joyce Hens Green in Washington granted Amtrak's request for a temporary restraining order and instructed union officials not to conduct any job actions, such as refusing to work overtime or calling in sick. "If that's what's been ordered, that's what we'll do," said Joseph E. Burns Jr., president of District 22 of the International Assn. of Machinists and Aerospace Workers. The striking workers said layoffs in New Orleans and New Haven, Mass., prompted the walkout.