Metro Rail constructs RoB at Malakpet in just 25 days

Hyderabad Metro Rail Limited (HMRL) completed the main span of Malakpet Metro ROB covering a length of 164 feet in just 25 days this month.

This is a new record in the country in ROB construction, said HMRL Managing Director NVS Reddy. Apart from engineering challenges, the HMRL had to complete the task of launching segments at Malakpet during three-hour period after midnight as permitted by railways.

During this block period, train operations were suspended for executing the works.Construction of Malakpet RoB posed multiple challenges to HMRL due to the presence of an open nala and a narrow rail under bridge through which heavy traffic passes almost round-the-clock.“Be very careful about Malakpet ROB.

This can be very tricky as the location is a high risk area from engineering point of view,” SK Jain, former Member Engineering, Railway Board and consultant for the project had advised Reddy.Malakpet Metro ROB had to be constructed on a curve at a height of about 58 feet over the narrow portion of NH 65 and over an already existing railway bridge adjacent to Malakpet railway



station. As in the case of the recently completed Begumpet ROB, here also “Bridge Builder” method of construction was used. Two huge 100 ton bridge builders were mounted on to the already built Metro viaduct on both sides of the ROB (i.e.), on Dilsukhnagar side and Nampally ends. 

The total bridge was built in three portions with the main span length being 164 feet and both ends being 98 feet and 131 feet on Dilsukhnagar and Nampally sides, respectively. To avoid any glitches, the bridge conditions were simulated in the Uppal casting yard. The segments were pre-cast in a “match casting” mode and these precast segments were brought to Malakpet and launched one after one with the help of heavy duty crane and the bridge builders in a sequential manner from both sides.

The main portion of the Metro ROB over the existing Malakpet railway bridge was constructed with 12 precast segments. Each segment was lifted using heavy duty cranes and placed on the previously laid trolley on top of the deck slab and held by the bridge builder with the help of a winch of 80 ton capacity.