Almost all the routes in the country can be electrified.
The Hill train routes are considered Heritage routes now. So they cannot be electrified, or else they will lose their heritage status. Besides, they are mainly for tourists. So, IR will retain Steam/diesel traction on them.
As...
more... of now, the routes that cannot be electrified are -
- Ernakulam - Cochin Harbour terminus
- Arakkonam - Takkolam old route
Both these routes lie beside military air bases and the electrification will violate the military's engineering rules. So, they cannot be electrified. IR has already opened an alternate route between Arakkonam and Takkolam, and the ERS-CHTS route probably won't see passenger traffic anymore.