Complex sentence: The new line was built to the north of the Old Man River and required two large bridges, one just west of Lethbridge-the famous High Level Bridge-over the Belly River and another over the Old Man River west of Monarch.
Split into simpler sentences: The new line was built to the north of the Old Man River. It required two large bridges, one just west of Lethbridge-the famous High Level Bridge-over the Belly River and another over the Old Man River west of Monarch.