The Athi River Super Bridge is the longest bridge on the Mombasa–Nairobi Standard Gauge Railway (SGR). It was built to carry a single-track railway line over the Athi River as it approaches the Kenyan capital city of Nairobi. At the time of its construction, the 2.6 km (1.6 mi) bridge was the sixth-longest bridge in Africa and the second-longest railway bridge, exceeded only by the Dona Ana Bridge at 3.67 km (2.28 mi).