State Highway 18 is a State Highway in Kerala

Kerala

or Keralam is an Indian state located on the Malabar coast of south-west India. It was created on 1 November 1956 by the States Reorganisation Act by combining various Malayalam speaking regions....

that starts from
Munnar and ends at the Kerala State Boundary. The highway is 57.3 km long.

The Route Map

Munnar (starts from km 113/6 of Aluva - Munnar road) - Madypatty dam - Indo Swiss Project Gate - Top Station - State boundary - Road continues to Tamil Nadu as part of Kodaikanal–Munnar Road