BENGALURU: A significant milestone in Bengaluru Metro's KR Puram to Kempegowda International Airport (KIA) Line was achieved on Friday night when the maiden pile cap for the Bagalur Cross Metro station.
The cap is laid over six piles, which are concrete foundation members that run 25 metres below the ground. Nearly 200 pile caps will be put in place in the 17 stations of this 37-km Phase-2B line.
NCC Ltd has been awarded the contract for 15 stations on this line, split into three packages. Most of the station is elevated barring a 900 metre stretch in the last station at KIA, which goes underground.
A top Metro official said, "This station figures in Package 2 of the Airport Line that extends from Hebbal to Bagalur Cross. The pile cap for the viaduct (on which rails are laid) have been laid in all three packages of the line. But it is the first that the cap for a station has been readied. Piling is the crucial part in the construction of any station as the real challenge lies when construction goes beneath the ground."
Piling is of crucial importance as the load of the structures above gets transferred to the soil depth thereby contributing to a solid foundation. "Each pile beneath the cap is separated at a 3-metre distance from the other,” he added. The number of pile caps required in a station range between 7 and 14. It takes anywhere between 20 and 25 days to ready a pile cap if everything goes as per plan," he said.
This line has five elevated stations at Hebbal, Kodigehalli, Jakkur Cross, Yelahanka and Bagalur Cross. The first viaduct pile cap for the Airport Line too was laid only at Bagalur Cross on March 27.
Explaining the challenges involved at Bagalur Cross during piling, the official said the ground profile proved tough. "The land below had extreme variations and would be very high at one spot and very low at another place. So, bringing them to the same level was tough," he added.
Package One from KR Puram to Hebbal as well as the Package-2 has a few pier caps readied for the viaduct while Package 3 from Bagalur Cross to KIA already has 30 pile caps readied for its viaduct.