State Highway 18 is a 32 km-long stretch that links the hill stations, Munnar
and Top Station, in Idukki District
. State Highway 18 starts from km 113/6 of Aluva
-Munnar Road (State Highway 18) and moves north-east touching Mattupetty
and Indo-Swiss Project Gate, before reaching Top Station. The State Highway 18 ends at the Kerala
border though the road actually continues in to Tamil Nadu territory (this part of the road is under the administration of Tamil Nadu government).