Hyderabad Metro rail project has created a construction record today with the erection of the 1.000th viaduct span and completion of 27 Km of metro viaduct in just 20 months.
The first span was erected in December 2012, the 1,000th span was erected today.
This marks completion of 38 per cent of the viaduct works (out of a total of 2,665 spans required for 72 km) so far, according to a statement from Hyderabad Metro.
Mumbai took about seven years to complete 11 km of Metro viaduct, Bangalore and Chennai took over 5 years to complete about 25 km of viaduct each; and Delhi took more than 3 years to achieve the same, the statement further mentioned.
On being informed by MD of Hyderabad Metro, NVS Reddy, about this engineering feat, the Chief Minister K.Chandrasekhar Rao congratulated the team of engineers in HMR and L&T.
As on date 1,473 foundations (56 per cent), 1,370 pillars (52 per cent) are completed, he stated.
The Government facilitated setting up of India’s two biggest precast yards, one at Uppal in 70 acres and another one at Qutubullahpur in 62 acres.
L&T then established factory-like precast yards with sophisticated machinery like automatic steel cutting and bending machines etc., to produce precast segments each weighing about 40 tonnes.
These precast segments are being transported in the night on low bedded trolleys to various Metro construction sites and erected between Metro pillars with the help of “launching girders”. In all, 15 launching girders are being used to carry out these erection works simultaneously at several spots.
While the average length between 2 pillars is 100 feet which is bridged with 11 precast segments, the average length between 2 station pillars is about 50 feet which is bridged with six precast segments. After dry matching these prearranged segments, they are glued and tied with a bunch of iron strands from inside, which are elongated to their maximum capacity in “post tensioning” method and then permanently grouted. These viaduct spans can withstand heavy loads and 21 types of stresses caused by two running trains and natural forces including heavy gales and earthquakes.
This kind of precasting method where almost 85 per cent of the Metro works has facilitated rapid construction and minimum inconvenience to road users.
Usage of hi-tech shuttering material; single pour of concrete upto 40 feet height with very good surface finish; usage of curing compounds instead of conventional water curing; multilevel quality checks ensuring safety and good quality works; and other global best conspractices have already won Hyderabad Metro many awards including “The Global Engineering Project of the Year," V.B. Gadgil, MD of L&T Metro Rail Hyderabad Limited, said.
