Complex sentence: The Act for the West Durham Railway, received Royal Assent on 4 July 1839, after opened on 12 June.An extension of the Byers Green branch to Willington Colliery, the line included a bridge over the River Wear with gradient of 1 in 28.
Split into simpler sentences: The Act for the West Durham Railway, effectively an extension of the Byers Green branch to Willington Colliery, received Royal Assent on 4 July 1839, after had opened on 12 June. The line included a bridge over the River Wear with gradient of 1 in 28.