Complex sentence: In the second half of the 19th century, the need to facilitate access to the harbour for hundreds of trucks laden with potatoes and other produce for export prompted a programme of road-widening which swept away many of the ancient buildings of the town centre.
Split into simpler sentences: In the second half of the 19th century, hundreds of trucks laden with potatoes and other export produce needed access to the harbour. This prompted a programme of road-widening which swept away many of the ancient buildings of the town centre.