For many reasons. The top being Environmental concerns. The Dec 2004 Tsunami did not affect coastal Communities lying below the Sethu. The Sethu acted as a break water saving millions of lives. Also, the Coral Gardens in the area can be damaged. http://www.slideshare.net/kalyan97/rama-setu-ppt/ ALTERNATIVE: Build a ESCALATOR spanning the Sethu which will take ships up a Ramp, cross over the Sethu for a distance of a mile and Gently allow them to slide across the other side.
