Trivanrum-Kilimanoor-Kottarakkara-Kottayam-Moovattupuzha-Thodupuz ha-Adimaly-Munnar.This road is the shortest and now relatively in good condition.All the distance is high way.Expect some traffic congestion in between
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from trivandrum drive to alwaye via kollam, allapuzha, ernakulam.
from alwaye take the road to perumbavoor and once u reach perumbavoor, take the road to kootukura.
that is the starting point to go to munnar.