The name 'Saraighat' came from Saraighat, a place near Guwahati in Assam, on the north bank of the river Brahmaputra. Sarai was a village and it is famous for the ‘Battle of Saraighat’, which was fought near this place on the Brahmaputra River. The Battle was fought between the Mughal empire and the Ahom Kingdom led by famous Lachit Barphukan in 1671. There is a park named Saraighat War Memorial Park at Agyathuri on the northern bank of river Brahmaputra which was constructed for preservation and promotion of the memories associated with the Battle of Saraighat.
The construction of the bridge was started in January, 1958. It was built immediately after the Indo-Chinese war. The bridge’s length is 1492 meters (about 1.5 kms). The bridge has a national highway on top and railway tracks below. It was opened to goods traffic in Oct, 1962 by the then Prime Minister Jawaharlal Nehru. Later, on 7 June 1963, the bridge was opened for passenger traffic. The estimated cost of the bridge was roughly Rs.10 Cr ($2.2M). The famous Chilarai Park or Lachit Udyan is situated near the bridge.
Ref – 1. http://assamthenortheastofindia.blogspot.com/2008/12/saraighat-bridge-over-mighty.html; 2. http://en.wikipedia.org/wiki/Saraighat_bridge; 3. http://tourismassam.blogspot.com/2008/02/places-to-visit-in-central-assam-kamrup.html