Complex sentence: Crowds waited for the train to cross the Stockton to Yarm turnpike and approaching Stockton it gained speed and again reached, when a man clinging to the outside of a waggon fell off and his foot was crushed by the following vehicle.
Split into simpler sentences: Crowds waited for the train to cross the Stockton to Yarm turnpike. Approaching Stockton it gained speed and reached again, before a man clinging to the outside of a waggon fell off and his foot was crushed by the following vehicle.