Hello shivaay raj , I'll be happy to answer your travel queries from my experience ☺️☺️.
*that's so sad to hear that due to natural conditions ,you are forced to replace your green plans of Coorg to goa . obviously both can't be compared .
*
Alright,as per your query , Bangalore to Goa via NH 48 This is the shortest, fastest, and most convenient route. This is also the only designated route suggested by GPS and live maps. Most travelers opt for this route because the Bangalore to Goa traffic here is much lighter and makes it better to drive through. *infact,the journey of banglore to goa is considered one of the most picturesque ones .I hope you enjoy this beautiful roadtrip.
*The road conditions are excellent. Drive safe as the roads in Western ghats are curvaceous. my recommendation is to go by one road for onward journey and return by the other depending on where you will be staying in Goa. There are other routes from Bangalore to Goa as well like hubli-anwad ghat route,Karwar route,belgaum route and twin falls route .
*I have a small suggestion for you, I just checked online and found that there are some great deals on tripoto for goa ,do check out this link
https://www.tripoto.com/goa/tour-packages HAPPY TRAVELLING 💗