Complex sentence: Bridges of this type were useful since the Inca people did not use wheeled transport-traffic was limited to pedestrians and livestock-and they were frequently used by Chasqui runners delivering messages throughout the Inca Empire.
Split into simpler sentences: Bridges of this type were useful since the Inca people did not use wheeled transport--traffic was limited to pedestrians and livestock. They were frequently used by Chasqui runners delivering messages throughout the Inca Empire.