By JOSH FUNK
AP Business Writer
OMAHA, Neb. (AP) — BNSF railroad is tweaking its strict new attendance policy. But unions that have challenged the rules that took effect in February say the changes don’t go far enough. The railroad told employees that starting next month it will make several small changes in the formula it uses to determine whether workers are missing too many shifts. The unions say the rules still do too much to encourage workers to show up when they are sick or fatigued. They say the rules have contributed to more than 700 employees leaving the railroad at a time when BNSF is struggling to hire.