The Trump administration wants to make sure that the Mexican train crews hauling freight just over the border can understand key safety information in English and that the common practice of using foreign crews to cross into America doesn’t threaten U.S. jobs. Two major rail unions praised the proposed rule that was announced Friday. Other proposed changes would also strengthen the standards for certifying crews for safety. The Union Pacific and CPKC railroads would be directly affected by the restrictions on Mexican crews. Those railroads have said they are committed to operating safely and following rules. The Association of American Railroads trade group declined to comment while it studies the rule.