KR route doubling is 100% possible without disturbing present single existing line. I know there is many tunnels & bridges in KR & laying of second line in plain terrain in KR in patch is easy possible. Only issue is boring the tunnels in mountains & making bridges. If KRCL start the tunnels boring works in 10 feets distance of present existing tunnels then creating another tunnels for second line is possible. Construction of bridges for second line is also possible if works started in 10 feets distance of present existing bridges. KRCL engineers is best and experts in making longest tunnels boring machines & making longest & highest bridges with advances machinery.