HMRL erects 1000 viaduct span to create record

Hyderabad, July 27 (INN): The Hyderabad Metro Rail project has created an all India construction record on Sunday with the erection of the 1000th viaduct span and completion of 27 Km of Metro viaduct in just 20 months.

While the 1st span i.e., bridging the gap between two pillars, was erected near GENPACT in Habsiguda in December 2012, the 1000th span near S.R. Nagar Bus stop is erected today. This accounts for completion of 38% of the viaduct works (out of a total of 2665 spans required for 72 Km) so far.

Mumbai took about seven years to complete 11 km of Metro viaduct; Bangalore and Chennai took over five years to complete about 25 Km of viaduct each; and Delhi took more than three years to achieve the same.

On being informed by HMRL MD NVS Reddy about this all India engineering record achieved by the Hyderabad Metro, Chief Minister K Chandrasekhar Rao congratulated him and his team of engineers in HMR and L&T.

This kind of spectacular engineering feat of fast construction in congested roads of Hyderabad with a good safety record was possible due to a number of proactive measures taken by the State Government and HMR and the engineering capabilities of L&T, said NVS Reddy. As on date 1473 foundations (56%), 1370 pillars (52%) are completed, he stated.

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 tons.

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. The so erected 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% of the Metro works including station construction are precast, has facilitated super fast construction and minimum inconvenience to road users.

Usage of state of the art 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 construction practices have already won Hyderabad Metro several international and national awards including 'The Global Engineering Project of the Year' award for 2013 at the 6th Global Leadership Forum in New York; RoSPA (Royal Society for Prevention of Accidents) 'Gold' awards for 2013 and 2014 at Glasgow (UK), 'Metro Rail Project of the Year ' 2013' at Mumbai, etc., stated LTMRHL MD V.B. Gadgil.