Inca rope bridges were simple suspension bridges over canyons and gorges and rivers (pongos) to provide access for the Inca Empire. Bridges of this type were useful since the Inca people did not use wheeled transport—traffic was limited to pedestrians and livestock. The bridges were an integral part on the Inca road system and are an example of Inca innovation in engineering. They were frequently used by Chasqui runners delivering messages throughout the Inca Empire.