Complex sentence: On December 30,2013, a westbound BNSF train carrying soybeans derailed approximately one mile west of Casselton, then an adjacent eastbound BNSF train carrying crude oil struck wreckage from the westbound train.
Split into simpler sentences: On December 30,2013, a westbound BNSF train carrying soybeans derailed approximately one mile west of Casselton. An adjacent eastbound BNSF train carrying crude oil struck wreckage from the westbound train.