As part of plans to upgrade existing single track railway between Castlerock (Karnataka) and Vasco-da-Gama (Goa) to a double line, Indian railways will build a parallel line. Only that the parallel line will be underground to prevent tree cutting and other damage to environment. A 12.5 km tunnel will be the parallel line.

https://goachronicle.com/south-western-railways-double-tracking-boosts-infrastructure/