IntroductionAny underground construction work is always an engineering challenge. Construction work below the surface requires precision in planning and absolute competence in execution since even a minor error or oversight on the part of the engineers may lead to disastrous results.
And when the underground construction work involves tunnelling below an already operational Metro tunnel and expansion of the adjacent Metro station into a major interchange hub of the network, the challenges confronting the engineers obviously increase manifolds.
The Hauz Khas interchange Metro station project of the third phase of Delhi Metro's expansion was taken up with such difficult challenges. The already operational Hauz Khas Metro station on the Jahangirpuri – HUDA City Centre Metro corridor (yellow line) had to be expanded into an interchange facility, the new tunnel had to pass below an already functional Metro tunnel and all this had to be achieved without hampering passenger services even for an hour on the yellow line.
To further add to the woes was the busy Outer Ring Road running adjacent to the construction area. Being one of Delhi's arterial roads, thousands of vehicles used the road every hour and it was absolutely impossible to stop or divert traffic on such a busy road even for short durations.