Nallapadu–Nandyal section was constructed as a Meter Gauge railway line in 1891/92 by the British. The Magnificent Dorabhavi Viaduct used to span in the Nallamalla Range. The Viaduct 1,024 metres (3,360 ft) long spanning over 8 high pillars around 125 metres (410 ft) was an architectural & engineering wonder. The Viaduct was dismantled after the Guntur Junction–Guntakal Junction section was made Broad Gauge in 1997/98. The 1,350 metres (4,430 ft) long Bogada Tunnel & 1,250 metres (4,100 ft) long Chellama Tunnel in the Meter Gauge alignment were sealed in 1997/98 & a new 1,600 metres (5,200 ft) long Bogada Tunnel & 1,000 metres (3,300 ft) long Chellama Tunnel were constructed in 1997/98 in the Broad Gauge line. Guntur Junction–Guntakal Junction section is 401 kilometres (249 mi) long & currently doubling of Nandyal & Guntakal is going on.