Hyderabad, Feb 18 : Engineers of Hyderabad Airport Metro Ltd (HAML) are facing enormous technical challenges in the alignment of the Airport Metro on the critical stretch from Raidurg station to Nanakramguda junction. With multiple flyovers, underpasses and high-rise buildings along this stretch, the engineers are studying various options to design the metro line. Adviser (Civil Engineering), HAML and former Member Engineering, Railway Board Subodh Jain on Saturday inspected the proposed alignment along with HAML MD N.V.S. Reddy and senior engineers of HAML. According to engineers, crossing Mindspace junction at a height of about 21 meters (69 feet), which has an underpass, rotary and flyover, is a major challenge. Different options of laying the metro viaduct with smaller spans with pre-stressed concrete girders in situ that is at site construction, or erection of a 90 meter (295 feet) long special span with composite steel girder will be examined. While deciding the span lengths, girder type and construction method, the construction drawings of the underpass, rotary and flyover will be obtained from Greater Hyderabad Municipal Corporation (GHMC) and analysed. Different design options for the new integrated Raidurg station on the extended metro corridor 3 (Blue Line) and the Airport Metro station will be examined mainly from a passenger convenience point of view. This multi level interchange station will be designed in such a way to avoid shifting of the extra high voltage 400 kV underground cables adjacent to it. The airport metro viaduct crossing the multi level flyover at Biodiversity junction at a height of about 20 meters (66 feet) is another engineering challenge. Airport metro pillars will be located away from the flyover pillars in a staggered way to avoid any adverse effect on the foundations of the flyover pillars. The obligatory span crossing over the flyover can be planned as "cast in situ" pre-stressed concrete girders. The foundation stone for the Airport Metro, which will connect the information technology district Hitec City to Rajiv Gandhi International Airport at Shamshabad, was laid on December 9, 2022. The 31-km long project will be built by the state government at a cost of Rs 6,250 crore. /IANS